59 results on '"Alex Zakhidov"'
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2. A density functional theory study on the interface stability between CsPbBr3 and CuI
- Author
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Aron Walsh, Young-Kwang Jung, Alex Zakhidov, Luisa M. Scolfaro, and Eric W. Welch
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Technology ,Materials science ,Offset (computer science) ,EFFICIENCY ,Materials Science ,0205 Optical Physics ,General Physics and Astronomy ,CONDUCTOR ,Materials Science, Multidisciplinary ,02 engineering and technology ,Epitaxy ,01 natural sciences ,Band offset ,Physics, Applied ,Lattice constant ,THIN-FILMS ,0103 physical sciences ,Nanoscience & Nanotechnology ,0206 Quantum Physics ,Perovskite (structure) ,BROMIDE LASER ,010302 applied physics ,Bulk modulus ,Science & Technology ,Condensed matter physics ,Physics ,TOTAL-ENERGY CALCULATIONS ,Charge density ,DEFECTS ,021001 nanoscience & nanotechnology ,PROCESSED COPPER IODIDE ,lcsh:QC1-999 ,LEAD HALIDE PEROVSKITES ,0906 Electrical and Electronic Engineering ,LAYER ,Physical Sciences ,Science & Technology - Other Topics ,Density functional theory ,0210 nano-technology ,lcsh:Physics - Abstract
This paper assesses the interface stability of the perovskite CsPbBr3 and transport layer CuI using density functional theory and band offset calculations. As a low-cost, more stable alternative to current hole transport materials, CuI may be used to template the epitaxial growth of perovskites such as CsPbBr3 owing to a 1% lattice constant mismatch and larger bulk modulus. We compare all eight atomic terminations of the interfaces between the (100) low-energy facet for both CsPbBr3 and CuI, increasing material thickness to consider charge density redistribution and bonding characteristics between surface and bulk-like regions. A low energy atomic termination is found to exist between these materials where alternating charge accumulation and depletion regions stabilize bonds at the interface. Band offset calculations reveal a type I straddling gap offset in the bulk shifting to a type II staggered gap offset as the thickness of the materials is increased, where the built-in potential changes as layer thickness increases, indicating the tunability of charge separation at the interface. CuI may, thus, be used as an alternative hole transport layer material in CsPbBr3 optoelectronic devices.
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- 2020
3. Polarons in Halide Perovskites: A Perspective
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Amanda Neukirch, Eric W. Welch, Dibyajyoti Ghosh, Alex Zakhidov, and Sergei Tretiak
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Band splitting ,Materials science ,Halide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Polaron ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,General Materials Science ,Charge carrier ,Physical and Theoretical Chemistry ,0210 nano-technology ,Carrier dynamics - Abstract
Metal halide perovskites (MHPs) have rapidly emerged as leading contenders in photovoltaic technology and other optoelectronic applications owing to their outstanding optoelectronic properties. After a decade of intense research, an in-depth understanding of the charge carrier transport in MHPs is still an active topic of debate. In this Perspective, we discuss the current state of the field by summarizing the most extensively studied carrier transport mechanisms, such as electron-phonon scattering limited dynamics, ferroelectric effects, Rashba-type band splitting, and polaronic transport. We further extensively discuss the emerging experimental and computational evidence for dominant polaronic carrier dynamics in MHPs. Focusing on both small and large polarons, we explore the fundamental aspects of their motion through the lattice, protecting the photogenerated charge carriers from the recombination process. Finally, we outline different physical and chemical approaches considered recently to study and exploit the polaron transport in MHPs.
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- 2020
4. Optical dispersion study of PPDT2FBT by spectroscopic ellipsometry
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C. Howlader, Mehedhi Hasan, Alex Zakhidov, and Maggie Yihong Chen
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Materials science ,business.industry ,Spectroscopic ellipsometry ,Optoelectronics ,business - Published
- 2020
5. Ambient Processing Conditions and Their Effects on Perovskite Device Performance
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Christopher Manspeaker, Garrett Merrion, Kevin Krouse, and Alex Zakhidov
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General Materials Science ,General Chemistry ,Condensed Matter Physics - Published
- 2022
6. Controlled Growth of MoS2 Flakes from in-Plane to Edge-Enriched 3D Network and Their Surface-Energy Studies
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Mukesh Kumar, Naveen Kumar, F.C. Robles Hernández, Abhay V. Agrawal, Christopher Manspeaker, Swaminathan Venkatesan, Zhuan Zhu, Jiming Bao, and Alex Zakhidov
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Inert ,Materials science ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface energy ,0104 chemical sciences ,Volumetric flow rate ,Contact angle ,Field emission microscopy ,symbols.namesake ,Chemical engineering ,Transmission electron microscopy ,symbols ,General Materials Science ,0210 nano-technology ,Raman spectroscopy - Abstract
Controlled and tunable growth of chemically active edge sites over inert in-plane MoS2 flakes is the key requirement to realize their vast number of applications in catalytic activities. Thermodynamically, growth of inert in-plane MoS2 is preferred due to fewer active sites on its surface over the edge sites. Here, we demonstrate controlled and tunable growth from in-plane MoS2 flakes to dense and electrically connected edge-enriched three-dimensional (3D) network of MoS2 flakes by varying the gas flow rate using tube-in-tube chemical vapor deposition technique. Field emission scanning electron microscope results demonstrated that the density of edge-enriched MoS2 flakes increase with increase in the gas flow rate. Raman and transmission electron microscopy analyses clearly revealed that the as-synthesized in-plane and edge-enriched MoS2 flakes are few layers in nature. Atomic force microscopy measurement revealed that the growth of the edge-enriched MoS2 takes place from the in-plane MoS2 flakes. On the ...
- Published
- 2018
7. Photoactivated Mixed In-Plane and Edge-Enriched p-Type MoS2 Flake-Based NO2 Sensor Working at Room Temperature
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Mahesh Kumar, Swaminathan Venkatesan, Abhay V. Agrawal, Alex Zakhidov, Rajesh Kumar, Guang Yang, Jiming Bao, and Mukesh Kumar
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Fluid Flow and Transfer Processes ,Materials science ,business.industry ,Sensing applications ,Process Chemistry and Technology ,Kinetics ,Bioengineering ,02 engineering and technology ,Edge (geometry) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Toxic gas ,01 natural sciences ,0104 chemical sciences ,In plane ,Improved performance ,Transition metal ,Optoelectronics ,Enhanced sensitivity ,0210 nano-technology ,business ,Instrumentation - Abstract
Toxic gases are produced during the burning of fossil fuels. Room temperature (RT) fast detection of toxic gases is still challenging. Recently, MoS2 transition metal dichalcogenides have sparked great attention in the research community due to their performance in gas sensing applications. However, MoS2 based gas sensors still suffer from long response and recovery times, especially at RT. Considering this challenge, here, we report photoactivated highly reversible and fast detection of NO2 sensors at room temperature (RT) by using mixed in-plane and edge-enriched p-MoS2 flakes (mixed MoS2). The sensor showed fast response with good sensitivity of ∼10.36% for 10 ppm of NO2 at RT without complete recovery. However, complete recovery was obtained with better sensor performance under UV light illumination at RT. The UV assisted NO2 sensing showed improved performance in terms of fast response and recovery kinetics with enhanced sensitivity to 10 ppm NO2 concentration. The sensor performance is also investig...
- Published
- 2018
8. Ultrafast zero-bias photocurrent and terahertz emission in hybrid perovskites
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Kuniaki Konishi, Petr A. Obraztsov, Alex Zakhidov, Natsuki Nemoto, D. A. Lyashenko, Alexander N. Obraztsov, Makoto Kuwata-Gonokami, Eric W. Welch, and Pavel A. Chizhov
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Photocurrent ,Materials science ,Spintronics ,business.industry ,Band gap ,Terahertz radiation ,Energy conversion efficiency ,General Physics and Astronomy ,lcsh:Astrophysics ,02 engineering and technology ,Anomalous photovoltaic effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,7. Clean energy ,lcsh:QC1-999 ,0103 physical sciences ,Femtosecond ,lcsh:QB460-466 ,Optoelectronics ,010306 general physics ,0210 nano-technology ,business ,lcsh:Physics ,Perovskite (structure) - Abstract
Methylammonium lead iodide is a benchmark hybrid organic perovskite material used for low-cost printed solar cells with a power conversion efficiency of over 20%. Nevertheless, the nature of light–matter interaction in hybrid perovskites and the exact physical mechanism underlying device operation are currently debated. Here, we report room temperature, ultrafast photocurrent generation, and free-space terahertz emission from unbiased hybrid perovskites induced by femtosecond light pulses. The polarization dependence of the observed photoresponse is consistent with the bulk photovoltaic effect caused by a combination of injection and shift currents. Observation of this type of photocurrents sheds light on the low recombination and long carrier diffusion lengths arising from the indirect bandgap in CH3NH3PbI3. Naturally ballistic shift and injection photocurrents may enable third-generation perovskite solar cells with efficiency exceeding the Shockley–Queisser limit. The demonstrated control over photocurrents with light polarization also opens new venues toward perovskite spintronics and tunable THz devices. The study provides new insight into the light-matter interactions of organic based perovskites. The authors do so by investigating the hybrid perovskite methylammonium lead iodide, which is considered a benchmark material for solar cells with high power conversion efficiency.
- Published
- 2018
9. Solution-processed organic light-emitting diodes with emission from a doublet exciton; using (2,4,6-trichlorophenyl)methyl as emitter
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Todd W. Hudnall, Alex Zakhidov, Renzo Arias Ugarte, Swaminathan Venkatesan, Eric Neier, and Nader Rady
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Materials science ,Band gap ,Exciton ,Analytical chemistry ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,01 natural sciences ,law.invention ,Biomaterials ,law ,Materials Chemistry ,OLED ,Electrical and Electronic Engineering ,Thin film ,Open shell ,business.industry ,Doping ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Optoelectronics ,0210 nano-technology ,business ,Light-emitting diode - Abstract
Neutral-π radical based open shell molecules foster new potential in light emitting diodes because of their theoretical near-equity quantum efficiencies. In this study, we report organic light emitting diodes (OLEDs) based on a novel open shell molecule (2,4,6-trichlorophenyl)methyl (TTM) as the electroluminescent layer. The singly occupied molecular orbital (SOMO) level and optical bandgap of TTM was calculated using cyclic voltammetry and UV–visible absorption respectively. Thermogravimetric analysis showed a stable molecule capable of sublimation. Two decidedly different approaches, thermal evaporation and solution processing, were employed to deposit TTM:host blend thin films for OLED device fabrication. OLED devices fabricated via thermal evaporation and solution processing yielded external quantum efficiencies of 2.78% and 0.28% and luminances of 330 cdm -2 and 78 cdm -2 respectively. Further, the effect of doping ratios of the host materials on OLED device performance were investigated and optimal ratios were established. We report for the first time solution processed open shell organic molecules for light emitting diode applications. Our results elucidate the potential for low-cost and high efficiency optoelectronic devices.
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- 2017
10. Role of interface in stability of perovskite solar cells
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Chris Manspeaker, Karen S. Martirosyan, Alex Zakhidov, and Swaminathan Venkatesan
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Materials science ,Interface (computing) ,Energy conversion efficiency ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Stability (probability) ,Durability ,0104 chemical sciences ,General Energy ,Degradation (geology) ,Chemical stability ,Electric power ,0210 nano-technology ,Perovskite (structure) - Abstract
The organo-halide lead perovskite solar cells (PSC) provide a cost effective method of acquiring sunlight energy and converting directly into electrical power with high conversion efficiency. However, the chemical stability of the PSC is a significant issue that is limiting practical application and prevents further device development. The device is extremely sensitive to moisture and may degrade during a few days. Recent investigation demonstrated that the materials, architecture and structure of the interface might play a crucial role in degradation rates and durability of the device. A systematic understanding of interfacial layers in stability of perovskite solar cells is essential to achieve highly stable devices for extensive industrial applications. This report is reviewing the role of interface in stability of perovskite solar cells and discussed their future trends and aspects.
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- 2017
11. Tailoring nucleation and grain growth by changing the precursor phase ratio for efficient organic lead halide perovskite optoelectronic devices
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Sandeep Sohal, Mehedhi Hasan, Junyoung Kim, Nader Rady, Alex Zakhidov, Yan Yao, Eric Neier, and Swaminathan Venkatesan
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Spin coating ,Materials science ,business.industry ,Inorganic chemistry ,Energy conversion efficiency ,Nucleation ,Halide ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Grain growth ,law ,Phase (matter) ,Materials Chemistry ,Optoelectronics ,Crystallization ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
The nucleation and growth of organic–inorganic hybrid perovskite films induced by the molar ratio of precursor components and their role in optoelectronic performance are investigated. Lead iodide (PbI2), methylammonium acetate (MAAc) and methylammonium iodide (MAI) mixed in different ratios were used as starting precursors for active layer deposition. While all the as cast films showed the presence of a precursor intermediate (PbIx·MAAc·MAI), the films derived from 1 : 1 : 1 and 1 : 0.5 : 1 ratios also exhibited crystallization of the perovskite (CH3NH3PbI3) phase during the spin coating process. The nucleation and crystallization of the perovskite phase in films derived from the equimolar precursor ratio were found to be the key to growing larger, smoother and single crystalline grains along the thickness leading to higher carrier lifetimes. Perovskite solar cells fabricated utilizing such a morphology showed a much higher power conversion efficiency irrespective of the active layer thickness. Furthermore, methyl ammonium bromide based perovskite light emitting diodes were also fabricated using the aforementioned equimolar precursor ratio which exhibited superior device performance compared to diodes with active layers derived from other precursor ratios. This work highlights a facile deposition technique and growth mechanism to attain reproducible, low cost and high-performance perovskite optoelectronic devices.
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- 2017
12. Accurate and Fast Thickness Measurement Technique of MAPbI3 Thin Film
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Mehedhi Hasan, Kevin Lyon, and Alex Zakhidov
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Materials science ,business.industry ,Band gap ,02 engineering and technology ,Molar absorptivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Wavelength ,Scratch ,Ellipsometry ,Optoelectronics ,Profilometer ,Thin film ,0210 nano-technology ,business ,computer ,Refractive index ,computer.programming_language - Abstract
In this work, we report the process of building an accurate ellipsometry model from scratch for benchmark hybrid perovskite MAPbI 3 . This model can be effectively utilized for a wide range of film thickness measurement. Optical constants from UV to infrared and bandgap of the film were extracted to implement the model. As developed models were evaluated by comparing the measured thicknesses using other direct measurement techniques such as profilometer, cross sectional SEM and AFM. Considering the level of complexity, time required for the measurement, area under measurement, sample preparation and accuracy, a comparison has been presented among different thickness measurement techniques. The process of ellipsometry model building can be used for other noble film with unknown pattern of optical constant with wavelength.
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- 2019
13. Second harmonic generation in CH3NH3PbI3 thin films (Conference Presentation)
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Irina V. Soboleva, Mehedhi Hasan, Anna A. Popkova, Andrey A. Fedyanin, D. A. Lyashenko, Vladimir O. Bessonov, and Alex Zakhidov
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Materials science ,business.industry ,Photovoltaics ,Scattering ,Optoelectronics ,Second-harmonic generation ,Nonlinear optics ,Direct and indirect band gaps ,Substrate (electronics) ,Thin film ,business ,Copper indium gallium selenide solar cells - Abstract
Methylammonium lead iodide (CH3NH3PbI3 or MAPI) is an organohalide lead perovskite, a promising material for optoelectronic application, e.g. in solar cells and photodetectors. It has a number of advantages over more traditional photovoltaics materials such as CIGS, GaAs, and even silicon due to facile solution processing, direct bandgap, high optical absorption, sufficiently high, balanced carrier mobilities, shallow trap defects and low-cost synthesis. At present moment there are number of article which reported measurement of second-harmonic generation in MAPI single crystals and presented contradictory results demonstrating the presence or absence of second-harmonic signal from MAPI. In this work, the second-harmonic generation (SHG) is observed in MAPI thin film that can be used as a base of high efficient solar sell. The SHG intensity from MAPI is measured to be at least three orders of magnitude more than one from substrate and encapsulation glasses. The MAPI nonlinear second-order susceptibility is estimated as compared to reference sample of y-cut quartz. In case of bulk contribution, the MAPI second-order susceptibility of 10-15 m/V is achieved. The polarization of SHG signal is experimentally studied in MAPI samples. The fraction of linearly polarized SHG signal is different for p- and s-polarization of fundamental wave and increases in case of p-polarized pump. The large non-polarized background of SHG signal is partly corresponded to SHG hyper-Rayleigh scattering. The hyper-Rayleigh scattering angle is experimentally estimated using the diaphragm behind the collimating objective lens and found to be less then 11 degrees.
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- 2019
14. Improvements of Organic Light‐Emitting Diodes Using Graphene as an Emerging and Efficient Transparent Conducting Electrode Material
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Alex Zakhidov, Gary W. Beall, Adeniji E. Adetayo, and Tanjina N. Ahmed
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Electrode material ,Materials science ,Graphene ,law ,business.industry ,OLED ,Optoelectronics ,Electroluminescence ,business ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention - Published
- 2021
15. Determining the refractive index and the dielectric constant of PPDT2FBT thin film using spectroscopic ellipsometry
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Alex Zakhidov, Maggie Yihong Chen, C. Howlader, and Mehedhi Hasan
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Materials science ,Band gap ,02 engineering and technology ,Dielectric ,010402 general chemistry ,01 natural sciences ,law.invention ,Inorganic Chemistry ,law ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Thin film ,Absorption (electromagnetic radiation) ,Spectroscopy ,business.industry ,Organic Chemistry ,Molar absorptivity ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Photodiode ,Attenuation coefficient ,Optoelectronics ,0210 nano-technology ,business ,Refractive index - Abstract
Despite the recent increase in PPDT2FBT polymer thin film applications for optoelectronic devices, a comprehensive study of this material's optical dispersion properties is unavailable. The optical properties of the PPDT2FBT thin film is investigated using variable-angle spectroscopic ellipsometry (VASE) at ambient conditions. Knowledge of optical dispersion properties is essential for designing and fabricating optoelectronic devices such as solar cells, photodetectors, and photodiodes. In this research, we determined the dielectric function of PPDT2FBT thin film using the B-spline model and then reproduced the dielectric function using Psemi-Tri oscillators. We estimated the refractive index (n) of the thin film to be between 2.00 and 2.15 and the extinction coefficient (k) to be in the range of 1.14–1.39 at a wavelength of 632.8 nm. We further verified the estimated optical properties from the model using directly measured quantities such as transmission and absorption data obtained using the ultraviolet–visible (UV–Vis) spectrometer and thicknesses obtained using a surface profilometer. In addition, we determined the optical band gap of PPDT2FBT using the absorption coefficient.
- Published
- 2020
16. Reliable Annealing of CH3NH3PbI3 Films Deposited on ZnO
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Patrick Scruggs, Jonathan Preiss, Christopher Manspeaker, D. A. Lyashenko, and Alex Zakhidov
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Imagination ,Electron transport layer ,Chemical substance ,Materials science ,Annealing (metallurgy) ,media_common.quotation_subject ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Solvent ,General Energy ,Magazine ,Chemical engineering ,law ,Solar cell ,Physical and Theoretical Chemistry ,0210 nano-technology ,Science, technology and society ,media_common - Abstract
CH3NH3PbI3 deposited on a ZnO electron transport layer is chemically unstable and decomposes at >80 °C, leaving PbI2 on the substrate along with traces of iodine. We found that this decomposition was reversible and could be prevented if a restricted volume solvent annealing procedure was applied. We also found that decomposition requires the presence of a certain amount of the processing solvent within the film. Finally, we developed a reliable annealing protocol for depositing perovskite film on ZnO, which resulted in the generation of repeatable solar cell devices.
- Published
- 2016
17. Integration of BiFeO3/La0.7Sr0.3MnO3 heterostructures with III–V semiconductors for low-power non-volatile memory and multiferroic field effect transistors
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Javad R. Gatabi, Pradip Dhungana, Md. Shafiqur Rahman, Liang Hong, Raghvendra K. Pandey, Robert F. Klie, Alex Zakhidov, J.S. Rojas-Ramirez, Susmita Ghose, Ravi Droopad, and Abbas Fahami
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Materials science ,business.industry ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Magnetic hysteresis ,01 natural sciences ,Ferroelectricity ,Non-volatile memory ,Condensed Matter::Materials Science ,Exchange bias ,Piezoresponse force microscopy ,0103 physical sciences ,Materials Chemistry ,Optoelectronics ,Condensed Matter::Strongly Correlated Electrons ,Field-effect transistor ,Thin film ,010306 general physics ,0210 nano-technology ,business ,Molecular beam epitaxy - Abstract
We report on the use of SrTiO3 films on GaAs(001) substrates grown by molecular beam epitaxy (MBE) as intermediate buffer layers for the heteroepitaxial growth of ferromagnetic La0.7Sr0.3MnO3 (LSMO) and room temperature multiferroic (ferroelectric/antiferromagnetic) BiFeO3 (BFO) thin films using the pulsed laser deposition technique. The exchange bias coupling effect in the BFO/LSMO heterostructure has been investigated. The magnetization measurements with field cooling exhibit a surprising increment in the magnetic moment with enhanced magnetic hysteresis squareness. This we believe is the consequence of exchange interactions between the antiferromagnetic BFO and the ferromagnetic LSMO at the interface. The integration of BFO materials with LSMO on GaAs substrates facilitated the demonstration of resistive switching based non-volatile memory (NVM) devices which can be faster with lower energy consumption compared to present commercial technologies. Ferroelectric switching observations using piezoresponse force microscopy show polarization switching demonstrating its potential for read–write operation in NVM devices. The ferroelectric and electrical characterization exhibits strong resistive switching with low set/reset voltages. Furthermore, we demonstrate a prototypical epitaxial field effect transistor based on multiferroic BFO as the gate dielectric and ferromagnetic LSMO as the conducting channel. The device exhibits a modulation in channel conductance with a high ON/OFF ratio. This work also demonstrates the first step towards the development of magneto-electronic devices integrated with a compound semiconductor.
- Published
- 2016
18. Low temperature atomic layer deposition of zirconium oxide for inkjet printed transistor applications
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Alex Zakhidov, Shamim Mahmud, Mahmuda Akter Monne, Mohi Uddin Jewel, and Maggie Yihong Chen
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Zirconium ,Materials science ,business.industry ,Graphene ,General Chemical Engineering ,Gate dielectric ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Substrate (electronics) ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Amorphous solid ,Atomic layer deposition ,chemistry ,law ,Optoelectronics ,0210 nano-technology ,business ,High-κ dielectric - Abstract
We report the growth of zirconium oxide (ZrO2) as a high-k gate dielectric for an inkjet-printed transistor using a low-temperature atomic layer deposition (ALD) from tetrakis(dimethylamido)zirconium (TDMAZr) and water precursors. All the samples are deposited at low-temperature ranges of 150–250 °C. The films are very uniform with RMS roughness less than 4% with respect to their thickness. The atomic force microscopy (AFM) shows a significant change in surface morphology from tapered posts to undulating mountain-like structures with several hundreds of ALD cycles. The results from X-ray diffraction (XRD) analysis exhibit an amorphous to the crystalline structure with temperature variation, which is independent of the thickness of the films. All our samples are hydrophilic as contact angles are less than 90°. The capacitance–voltage (C–V) and conductance–voltage (Gp/ω–V) characteristics of ZrO2 dielectrics for silicon metal–oxide–semiconductor (MOS) capacitors are studied for different temperatures. For the n-type substrate MOS capacitors, the dielectric constants are estimated to be 7.5–11. Due to the low deposition temperature, a hydrophilic surface, and high k value, the ALD-ZrO2 dielectric can be compatible for printed transistors. The processes of fabrication and characterization of inkjet-printed graphene transistors is demonstrated using the ZrO2 dielectric. The possible solvents, surfactant, and the dielectric induced modifications in graphene flakes are demonstrated by Raman spectra. The graphene flakes spread uniformly on the ZrO2 surface. The functional inkjet-printed graphene transistor characteristics are demonstrated to illustrate the field effect behavior with the ALD-ZrO2 dielectric.
- Published
- 2018
19. Thickness measurement of multilayer film stack in perovskite solar cell using spectroscopic ellipsometry
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Kevin Lyon, Lauren Trombley, Casey Smith, Alex Zakhidov, and Mehedhi Hasan
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010302 applied physics ,Materials science ,business.industry ,General Physics and Astronomy ,Perovskite solar cell ,02 engineering and technology ,Substrate (electronics) ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,lcsh:QC1-999 ,Indium tin oxide ,Stack (abstract data type) ,Ellipsometry ,0103 physical sciences ,Optoelectronics ,Thin film ,0210 nano-technology ,business ,Layer (electronics) ,lcsh:Physics ,Perovskite (structure) - Abstract
The rapid surge in perovskite solar cell efficiency has necessitated the development of viable metrology techniques during device integration, paving the way for commercialization. Ellipsometry is considered the most appropriate technique for fast and accurate thickness measurement for large scale production. However, a precise and well-calibrated model is a prerequisite for this technique. While ellipsometry of individual device layers has been reported in recent perovskite literature, a comprehensive multilayer modeling approach is thus far unavailable. Perovskite optoelectronic devices generally consist of a six-layer film stack with three transparent layers required for optical absorption in the perovskite layer. Spin casted thin films, now common in this line of research, impart their own difficulties into ellipsometric modeling. Roughnesses at each heterointerface, similarities in optical spectra of transparent layers, and anomalous dispersion of perovskite are just a few of such challenges. In this work, we report the process of building an ellipsometry model from scratch for thickness measurement of methylammonium lead iodide (MAPI) perovskite and indium tin oxide (ITO)/hole transport layer (HTL) bilayer thin film stacks on a glass substrate. Three promising representatives of HTLs (CuI, Cu2O, and PEDOT:PSS) were studied. The models were extended to measure the individual layer thicknesses of the MAPI/HTL/ITO film stack on a glass substrate using the models developed for individual layers. Optical constants of all the representative thin films were thus extracted for a wide wavelength range (300 nm–900 nm).
- Published
- 2019
20. Second Harmonic Generation in CH3NH3PbI3 thin films
- Author
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Irina V. Soboleva, Mehedhi Hasan, Alex Zakhidov, Vladimir O. Bessonov, Andrey A. Fedyanin, Anna A. Popkova, and D. A. Lyashenko
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Materials science ,Condensed matter physics ,Scanning electron microscope ,Scattering ,Second-harmonic generation ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,0104 chemical sciences ,Condensed Matter::Materials Science ,Nonlinear system ,X-ray crystallography ,MAPI ,Thin film ,0210 nano-technology - Abstract
The second-harmonic generation in CH3NH3PbI3 (MAPI) perovskite multidomain thin films is experimentally studied. The MAPI nonlinear second-order susceptibility is estimated. Polarization of MAPI SHG signal is experimentally observed and hyper-Rayleigh scattering angle value is estimated.
- Published
- 2018
21. Coexisting localized and extended optical Bloch states in a periodic deep wire array microcavity
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Robert Brückner, Franz Löchner, Andreas Mischok, Alex Zakhidov, Karl Leo, Hartmut Fröb, and Vadim G. Lyssenko
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Physics ,Photoluminescence ,Photon ,Condensed matter physics ,Physics::Optics ,Electron ,Photon energy ,Condensed Matter Physics ,Polarization (waves) ,Optical microcavity ,law.invention ,Effective mass (solid-state physics) ,law ,Rectangular potential barrier ,General Materials Science ,Electrical and Electronic Engineering - Abstract
We embed periodic SiO2 wires in an organic microcavity, producing a rectangular potential by the different optical thicknesses of the active layer due to the additional SiO2 layer. By μ -photoluminescence spectroscopy, we observe the energy dispersion of the photons and obtain discrete localized below and extended Bloch states above the potential barrier, respectively, showing that electro-magnetic waves can behave like massive particles, such as electrons, in crystal lattices. We investigate the dependencies on wire width and period and use the Kronig–Penney model to describe the photon energy dispersion, including an “effective mass” of a photon propagating through a microcavity implying polarization splitting. We obtain excellent agreement between experiment, simulation and analytical calculation.
- Published
- 2015
22. Solvent Toolkit for Electrochemical Characterization of Hybrid Perovskite Films
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Alex Zakhidov, D. A. Lyashenko, Mehedhi Hasan, Swaminathan Venkatesan, and Jason D. Slinker
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Inorganic chemistry ,Trihalide ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Characterization (materials science) ,Solvent ,chemistry.chemical_compound ,Hydrofluoroether ,Chemical engineering ,chemistry ,Thin film ,0210 nano-technology ,Perovskite (structure) - Abstract
Organohalide lead (hybrid) perovskites have emerged as competitive semiconducting materials for photovoltaic devices due to their high performance and low cost. To further the understanding and optimization of these materials, solution-based methods for interrogating and modifying perovskite thin films are needed. In this work, we report a hydrofluoroether (HFE) solvent-based electrolyte for electrochemical processing and characterization of organic-inorganic trihalide lead perovskite thin films. Organic perovskite films are soluble in most of the polar organic solvents, and thus until now, they were not considered suitable for electrochemical processing. We have enabled electrochemical characterization and demonstrated a processing toolset for these materials utilizing highly fluorinated electrolytes based on a HFE solvent. Our results show that chemically orthogonal electrolytes based on HFE solvents do not dissolve organic perovskite films and thus allow electrochemical characterization of the electronic structure, investigation of charge transport properties, and potential electrochemical doping of the films with in situ diagnostic capabilities.
- Published
- 2017
23. Photo-patterning of Highly Efficient State-of-the-Art Phosphorescent OLEDs Using Orthogonal Hydrofluoroethers
- Author
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Simone Hofmann, Simonas Krotkus, Malte C. Gather, Daniel Kasemann, Karl Leo, Alex Zakhidov, Fabian Ventsch, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. Biomedical Sciences Research Complex
- Subjects
Free state ,Materials science ,Phosphorescent oleds ,Hydrofluoroethers ,Doped organic layers ,Nanotechnology ,European Social Fund ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,QC Physics ,Orthogonal photolighography ,State (computer science) ,Phosphorescent OLEDs ,QC - Abstract
The authors kindly acknowledge the financial support by the Free State of Saxony, the Sächsische Aufbaubank (SAB, Project Nr. 100087862), and the European Social Fund (ESF). Photolithography offers a scalable solution for large area pixel patterning of organic light-emitting diode (OLED) displays. It has been limited due to the incompatibility of traditional processing steps with the majority of organic materials. In this work, photolithographic structuring of state-of-the-art phosphorescent red p-i-n OLEDs is demonstrated using fluorinated polymers in combination with hydrofluoroether solvents. This is the first report on photolithographically patterned OLEDs with state-of-the-art efficiency and good long-term stability. Postprint
- Published
- 2014
24. Zero- and π-States in a Periodic Array of Deep Photonic Wires
- Author
-
Andreas Mischok, Alex Zakhidov, Franz Löchner, Robert Brückner, Vadim G. Lyssenko, Karl Leo, Reinhard Scholz, and Hartmut Fröb
- Subjects
Free particle ,Materials science ,Condensed matter physics ,business.industry ,Physics::Optics ,Laser ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Brillouin zone ,Maxima and minima ,law ,Dispersion (optics) ,Photonics ,Parity (mathematics) ,business ,Photonic crystal - Abstract
A one-dimensional periodic rectangular potential, also known as the Kronig-Penney (KP) potential, transforms the parabolic dispersion of a free particle into a set of bands separated by bandgaps. However, if the potential wells are deep enough, the lowest bands converge into a set of single discrete states, numbered from j = 1 to j = jmax, which can be even or odd, describing the number of extrema. Here, discrete and continuous KP states are experimentally observed within a periodically modulated metal–organic microcavity. Depending on the width of the photonic wires, the thickness of the cavity, and the added metal grating, the parity of the highest localized state jmax can be either even or odd, leading to a complementary parity of the first continuous mode. The apex of this Bloch-like state in turn either starts at k = 0, or a π-state at the edges of the Brillouin zone, formed by the periodic metallic wires. An easy analytical explanation and numerical confirmation of zero- or π-phase locking for laser modes in spatially modulated microcavities are provided.
- Published
- 2014
25. 27.3L:Late-News Paper: Sub-pixel Structured OLED Microdisplay
- Author
-
Uwe Vogel, Alex Zakhidov, Rigo Herold, Bernd Richter, Karsten Fehse, and Markus Burghart
- Subjects
Pixel ,Computer science ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Lossy compression ,GeneralLiterature_MISCELLANEOUS ,Colored ,Feature (computer vision) ,Computer graphics (images) ,OLED ,Computer vision ,Color filter array ,Artificial intelligence ,business ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
New products, e.g. data-glasses and camera view finders demand highly efficient colored OLED microdisplays. State-of-the-art OLED microdisplays use lossy color filters. In this paper, we describe a novel microdisplay technology approach to structure OLED sup-pixels, with a feature size smaller than 10 μm in different colors.
- Published
- 2013
26. Combined alternative electrodes for semi-transparent and ITO-free small molecule organic solar cells
- Author
-
Anvar A. Zakhidov, Christoph Sachse, Lars Müller-Meskamp, Yong Hyun Kim, Alex Zakhidov, Jan Meiss, and Karl Leo
- Subjects
Materials science ,Fullerene ,Organic solar cell ,business.industry ,chemistry.chemical_element ,General Chemistry ,Carbon nanotube ,Condensed Matter Physics ,Polymer solar cell ,Electronic, Optical and Magnetic Materials ,Indium tin oxide ,law.invention ,Biomaterials ,chemistry ,PEDOT:PSS ,Aluminium ,law ,Electrode ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,business - Abstract
We investigate various electrode combinations of bottom and top contacts for organic photovoltaic (OPV) cells. Silver (Ag), indium tin oxide (ITO), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and silver nanowires (AgNW) are used as bottom electrodes. As top electrodes, thin silver layers (t-Ag) and free-standing carbon nanotube (f-CNT) sheets are employed. The manufactured zinc phthalocyanine (ZnPc): fullerene C 60 small molecule bulk heterojunction OPV cells with different kinds of bottom electrodes show efficiencies of 1.9∼2.2% and 1.1∼1.5%, when comprised of t-Ag and f-CNT top contacts, respectively. We demonstrate alternative electrodes beyond ITO, silver, and aluminum, which can be readily used for organic photovoltaics technology.
- Published
- 2012
27. Structural phase transition in pentacene caused by molecular doping and its effect on charge carrier mobility
- Author
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Björn Lüssem, Hans Kleemann, Alex Zakhidov, Moritz Riede, Karl Leo, and Christoph Schuenemann
- Subjects
Materials science ,Organic solar cell ,Condensed matter physics ,Doping ,Analytical chemistry ,General Chemistry ,Condensed Matter Physics ,Space charge ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Biomaterials ,Pentacene ,Organic semiconductor ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Field-effect transistor ,Crystallite ,Electrical and Electronic Engineering - Abstract
The structural properties and charge carrier mobility of pentacene doped by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) and 2,2-(perfluoronaphthalene-2,6-diylidene) dimalononitrile (F6-TCNNQ) are studied by X-ray diffraction, scanning electron microscopy, field effect transistor measurements, and space charge limited currents (SCLC). We observe the presence of polycrystalline and amorphous domains within the doped pentacene film grown under co-deposition conditions. The appearance of the amorphous phase is induced by the molecular dopants F4-TCNQ and F6-TCNNQ. A strong drop of crystallite size is obtained at a doping concentration of around 7 and 4 wt.%, respectively. The loss of the polycrystalline structure is correlated to a strong decrease of the charge carrier mobility in pentacene in horizontal and vertical film structures. We discuss typical scenarios of charge transport for polycrystalline and amorphous thin films in order to explain the observed loss of mobility originated by the doping induced structural phase transition. In this way an optimum doping concentration for highest conductivity with acceptable mobility is determined which can help to improve the performance of organic solar cells and organic high-frequency rectification diodes. © 2011 Elsevier B.V. All rights reserved.
- Published
- 2016
28. Phase-locked coherent modes in a patterned metal–organic microcavity
- Author
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Alex Zakhidov, Markas Sudzius, Robert Brückner, H. Fröb, Karl Leo, Reinhard Scholz, Vadim G. Lyssenko, and S. I. Hintschich
- Subjects
Materials science ,business.industry ,Phase (waves) ,Physics::Optics ,Dielectric ,Grating ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Metal ,Organic semiconductor ,Condensed Matter::Materials Science ,Optics ,visual_art ,visual_art.visual_art_medium ,Optoelectronics ,business ,Lasing threshold ,Plasmon - Abstract
By placing a thin silver grating inside a microcavity comprised of an organic semiconductor and two dielectric mirrors, researchers show that coherent emission can be selectively stimulated between in- and out-of-phase-locked arrays at room temperature. This work demonstrates that incorporating a lossy metal into a cavity does not suppress lasing.
- Published
- 2012
29. Direct structuring of C60 thin film transistors by photo-lithography under ambient conditions
- Author
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M. Anderson, Alex Zakhidov, Hans Kleemann, Karl Leo, Torben Menke, and Björn Lüssem
- Subjects
Materials science ,business.industry ,Nanotechnology ,General Chemistry ,Integrated circuit ,Condensed Matter Physics ,Structuring ,Electronic, Optical and Magnetic Materials ,Active matrix ,law.invention ,Biomaterials ,Organic semiconductor ,Semiconductor ,law ,Thin-film transistor ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,Photolithography ,business ,Lithography - Abstract
Direct structuring techniques are an indispensable need for future low-cost applications of organic semiconductor materials in e.g. active matrix displays or integrated circuits. We demonstrate direct structuring of a small molecule organic semiconductor by a photo-lithography lift off process under ambient conditions. To show compatibility of this process, we fabricate organic thin film transistors (OTFT) containing the benchmark electron transporting semiconductor C60 as active material in a top-contact geometry. C60 as electron transporting semiconductor serves as good indicator for contamination and degradation caused by the structuring procedure. To disclose influences of structuring, we discuss the OTFT performance for different channel lengths from 100 μm down to 2.7 μm. In particular, we show that lithography processing gives rise to increased contact resistances. Apart from that, mobility of C60 as material parameter is only weakly affected which underlines the compatibility of the suggested structuring procedure. The potential of this structuring procedure for future integration of driving transistors in active matrix displays is demonstrated.
- Published
- 2012
30. Detection of Transmitter Release from Single Living Cells Using Conducting Polymer Microelectrodes
- Author
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Brian N. Kim, Jin-Kyun Lee, Sang Yoon Yang, Manfred Lindau, Alex Zakhidov, George G. Malliaras, Priscilla G. Taylor, Christopher K. Ober, Materials Science and Engineering (MSE), Cornell University [New York], Département Bioélectronique (BEL-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-CMP-GC, and Malliaras, George
- Subjects
Materials science ,Polymers ,[SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,Chromaffin Cells ,Nanotechnology ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Article ,Catecholamines ,Coating ,PEDOT:PSS ,Adrenal Glands ,Animals ,General Materials Science ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,ComputingMilieux_MISCELLANEOUS ,Platinum ,Conductive polymer ,chemistry.chemical_classification ,Organic electronics ,Neurotransmitter Agents ,Bioelectronics ,Mechanical Engineering ,Tin Compounds ,Electrochemical Techniques ,Polymer ,Bridged Bicyclo Compounds, Heterocyclic ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Microelectrode ,chemistry ,Mechanics of Materials ,Electrode ,engineering ,Polystyrenes ,Cattle ,0210 nano-technology ,Microelectrodes - Abstract
The advent of organic electronics has made available a host of materials and devices with unique properties for interfacing with biology.1–2 One example is the use of conducting polymer coatings on metal electrodes that are implanted in the central nervous system and interface electrically with neurons, providing stimulation and recording the neuron's electrical activity.3–5 Coating a metal electrode with a conducting polymer has been shown to lower the electrical impedance and decrease the mechanical properties mismatch at the interface with tissue, with beneficial effects on the lifetime of the implant.3, 6 Conducting polymers can also be functionalized with biomolecules that stimulate neural growth and minimize the immune response to the implant.3–5, 7 Other examples are organic electronic ion pumps,8 and ion transistors,9 which are recently invented devices capable of precise delivery of neurotransmitters to neurons. These devices were recently implanted in the ear of a guinea pig and were shown to control its hearing.10 Conducting polymers such as poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), a material that has been shown to be biocompatible with a variety of different cells,1 have been used for these applications. These examples highlight the main advantages that organic electronic materials bring to the interface with biology, including their “soft” nature, which offers better mechanical compatibility with tissue than traditional electronic materials, and natural compatibility with mechanically flexible substrates, which paves the way for the development of implants that better conform to the non-planar shape of organs. Finally, the ability of organics to transport ionic in addition to electronic charge creates the opportunity to interface with electrically active cells in novel ways, as the work on ion pumps indicates.
- Published
- 2011
31. Correction: Integration of BiFeO3/La0.7Sr0.3MnO3 heterostructures with III–V semiconductors for low-power non-volatile memory and multiferroic field effect transistors
- Author
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Md. Shafiqur Rahman, Susmita Ghose, Liang Hong, Pradip Dhungana, Abbas Fahami, Javad R. Gatabi, Juan S. Rojas-Ramirez, Alex Zakhidov, Robert F. Klie, R. K. Pandey, and Ravi Droopad
- Subjects
Materials Chemistry ,General Chemistry - Abstract
Correction for ‘Integration of BiFeO3/La0.7Sr0.3MnO3 heterostructures with III–V semiconductors for low-power non-volatile memory and multiferroic field effect transistors’ by Md. Shafiqur Rahman et al., J. Mater. Chem. C, 2016, 4, 10386–10394.
- Published
- 2018
32. Semiperfluoroalkyl Polyfluorenes for Orthogonal Processing in Fluorous Solvents
- Author
-
Jin-Kyun Lee, Héctor D. Abruña, Priscilla G. Taylor, Mitk’El B. Santiago-Berríos, Andrew B. Holmes, Hon Hang Fong, Christopher K. Ober, Georgia E. McCluskey, Alex Zakhidov, and George G. Malliaras
- Subjects
chemistry.chemical_classification ,Materials science ,Photoluminescence ,Polymers and Plastics ,Organic Chemistry ,Nanotechnology ,Polymer ,Photoresist ,Electroluminescence ,Photochemistry ,law.invention ,Inorganic Chemistry ,chemistry ,PEDOT:PSS ,law ,Screen printing ,Materials Chemistry ,OLED ,Photolithography - Abstract
The challenging synthesis of semiperfluoroalkyl polyfluorenes and characterization of their electro-optical properties has been reported. Solutions of conjugated polymers can be dispensed onto the desired area by inkjet printing or screen printing, or form films on regions where a sacrificial photoresist material defines the target. Optical properties of the polyfluorenes, including absorption maxima of the UV vis spectra and photoluminescence are summarized. The EL characteristics areinestigated in a device structure of ITO PEDOT:PSS light-emitting polymer CsF Al. Their optical and EL properties were evaluated, exhibiting distinctive characteristics from their nonfluorinated analogues. Good performance and processability of P(R fF12- RfBTz) in fluorinated solvents enabled the fabrication of a patterned EL device by conventional photolithographic methods.
- Published
- 2010
33. A light-emitting memristor
- Author
-
Jason D. Slinker, Byungki Jung, Héctor D. Abruña, George G. Malliaras, and Alex Zakhidov
- Subjects
business.industry ,Stereochemistry ,Ionic bonding ,chemistry.chemical_element ,General Chemistry ,Memristor ,Electroluminescence ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,law.invention ,Ruthenium ,Biomaterials ,chemistry.chemical_compound ,Bipyridine ,chemistry ,Transition metal ,law ,Hexafluorophosphate ,Materials Chemistry ,Optoelectronics ,Light emission ,Electrical and Electronic Engineering ,business - Abstract
A light-emitting memristor (LEM) is reported based on a metal/mixed conductor/metal structure, where the mixed conductor is the ionic transition metal complex ruthenium(II) tris(bipyridine) with hexafluorophosphate counter ions. The device shows memory effects upon the application of an ac bias, in both current and electroluminescence intensity. The observation of memory in light emission offers the potential for optical read-out of the state of memristive devices.
- Published
- 2010
34. Electrochemically Tuned Properties for Electrolyte-Free Carbon Nanotube Sheets
- Author
-
Mel Zhang, Von Howard Ebron, Alex Zakhidov, Alan B. Dalton, Alexander Kuznetsov, Edgar Muñoz, John P. Ferraris, Joseph N. Barisci, Steve Collins, Anvar A. Zakhidov, Dongseok Suh, and Ray H. Baughman
- Subjects
Supercapacitor ,Materials science ,Dopant ,Nanotechnology ,Carbon nanotube ,Electrolyte ,Condensed Matter Physics ,Electrochemistry ,Elementary charge ,Electronic, Optical and Magnetic Materials ,law.invention ,Biomaterials ,Field electron emission ,Chemical engineering ,law ,Electrode - Abstract
Injecting high electronic charge densities can profoundly change the optical, electrical, and magnetic properties of materials. Such charge injection in bulk materials has traditionally involved either dopant intercalation or the maintained use of a contacting electrolyte. Tunable electrochemical charge injection and charge retention, in which neither volumetric intercalation of ions nor maintained electrolyte contact is needed, are demonstrated for carbon nanotube sheets in the absence of an applied field. The tunability of electrical conductivity and electron field emission in the subsequent material is presented. Application of this material to supercapacitors may extend their charge-storage times because they can retain charge after the removal of the electrolyte.
- Published
- 2009
35. Orthogonal Patterning of PEDOT:PSS for Organic Electronics using Hydrofluoroether Solvents
- Author
-
George G. Malliaras, Christopher K. Ober, Alex Zakhidov, Priscilla G. Taylor, John A. DeFranco, Margarita Chatzichristidi, Hon Hang Fong, and Jin-Kyun Lee
- Subjects
Conductive polymer ,Organic electronics ,Materials science ,business.industry ,Mechanical Engineering ,Photoresist ,law.invention ,Organic semiconductor ,PEDOT:PSS ,Mechanics of Materials ,law ,OLED ,Optoelectronics ,General Materials Science ,Photolithography ,business ,Lithography - Abstract
2009 WILEY-VCH Verlag Gmb Organic electronics is an emerging technology opening new opportunities in the field of large-area electronics. It has received enormous attention as a technology platform that enables flexible, large-scale devices by exploiting the unique properties of organic materials. In addition, organic electronics offer the possibility of affordable manufacture of devices through solution processing of active materials. Before this vision is realized, several challenges must be overcome, in particular the issues of patterning. Patterning of electronic materials enables microscale device structures to be defined for organic light-emitting diode (OLED) displays and organic thin-film transistors (OTFTs). In addition, patterning enhances the device performance by preventing cross-talk, increases transconductance, and prevents high off-currents in transistor arrays or drivers. The patterning of organic materials has been demonstrated by many different methods, including ink-jet printing, vapor deposition through shadow masks, soft and hard imprint lithography, and photolithography. Ink-jet printing boasts continuous roll-to-roll process capabilities and is the patterning technique of choice for polymeric materials. However, the resolution is limited to approximately 10–20mm. Shadow mask deposition is the dominant technique for small-molecule patterning, but also has notable resolution limitations. A shadow mask feature resolution is typically 25–30mm, although special masks have shown resolution down to 5mm. Shadow-mask deposition also requires a high-vacuum environment, which can introduce further limitations. Imprint lithography has demonstrated promising results, showing feature resolution down to 10 nm. However, this technique has shown only limited applicability with respect to materials and device architectures. Furthermore, in all of the aforementioned methods, registration is an issue that renders fabrication of multilayer devices exceptionally challenging. Multilayered device architecture will be essential to achieve fully integrated circuits. Photolithography, in contrast, is a widely applicable patterning method that consistently achieves both high-resolution and registration. Photolithography has the added advantage of being the most developed patterning technology and the patterning method of choice for the current semiconductor industry. In spite of the proven technical advantages, conventional photolithography has not been recognized as a suitable technique for patterning organic electronic materials. It is presently hindered by concerns of chemical deterioration of active organic materials upon exposure to process solvents for lithography. By introducing a new set of benign processes that involve new specially tailored photopolymers, we show that this problem can be circumvented. Recently, we identified hydrofluoroethers (HFEs), a family of nontoxic and environmentally friendly solvents, as being chemically benign to nonfluorinated organic electronic materials. Not only are they benign, but HFEs are orthogonal solvents to many organic compounds, that is, the organic compounds are insoluble and are not swollen in HFEs. This is a particularly useful property in the fabrication of multilevel devices, since new layers can be added without damage to existing ones. Our challenge was, therefore, to develop compatible lithographic materials for these new process solvents. By employing a fluorinated photoresist compatible with HFEs, we demonstrate sub-micrometer photolithographic patterning of organic electronic materials. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a mechanically flexible, transparent, and highly conductive polymer blend, which has found various applications in organic electronics including serving as the electrode material for plastic substrates, because of its low-temperature processing requirements, and as charge-injection/-extraction layers in OLEDs and photovoltaic devices. However, photolithographic patterning of PEDOT:PSS for device components is not straightforward, because i) PEDOT:PSS films are damaged by aqueous solutions, which are standard developers in conventional photolithography, and ii) acid-sensitive photoresists are adversely affected by the acidic PEDOT:PSS. In this communication,wepresent a unique acid-stable imaging material for PEDOT:PSS and organic electronic materials in general. We report on the sub-micrometer patterning of PEDOT:PSS films and their subsequent application to the fabrication of a field-effect transistor, in which an organic semiconductor material, pentacene, is patterned by the same protocol. In designing a HFE-compatible photoresist, it was most important that the photoresist be soluble in fluorous solvents. In general, fluorous solvents dissolve highly fluorinated materials. The copolymer 3, derived from the highly fluorinated monomer 1 and photolabile monomer 2, was expected to yield a material that exhibits a solubility switch following UV irradiation
- Published
- 2009
36. Orthogonal Processing: A Novel Photolithographic Patterning Method for Organic Electronics
- Author
-
George G. Malliaras, Alex Zakhidov, Christopher K. Ober, Ha Soo Hwang, Jin-Kyun Lee, Margarita Chatzichristidi, Hon Hang Fong, and Priscillia G. Taylor
- Subjects
Organic electronics ,chemistry.chemical_classification ,Materials science ,New horizons ,Supercritical carbon dioxide ,Fabrication ,Polymers and Plastics ,Organic Chemistry ,Nanotechnology ,Polymer ,law.invention ,Processing methods ,chemistry ,law ,Materials Chemistry ,Electronics ,Photolithography - Abstract
Organic electronics is an extensively studied subject opening new horizons in electronics technology. It has attracted great attention as a technology to enable flexible electronic devices through solution processing of organic and polymeric materials. However, patterning of organic materials to construct device components still remains one of the major hurdles to be overcome due to problems with chemical processing. Fundamentally this challenge originates from the limited number of options regarding orthogonal solvents. Recently, we have identified supercritical carbon dioxide (scCO2) and segregated hydrofluoroethers (HFEs) as universal, non-damaging solvents for most non-fluorinated polymeric materials. These unconventional solvents expand processing options from the two-dimensional plane to three-dimensional space by drawing another orthogonal axis. Taking advantage of those noble solvents and fluorinated photoresists, we were able to make patterns of functional organic materials photolithographically. Furthermore, our orthogonal processing method has been applied to the fabrication of a patterned polymer light-emitting device in scCO2 and an organic thin-film transisotor in HFEs.
- Published
- 2009
37. Hydrofluoroethers as Orthogonal Solvents for the Chemical Processing of Organic Electronic Materials
- Author
-
John A. DeFranco, George G. Malliaras, Margarita Chatzichristidi, Hon Hang Fong, Christopher K. Ober, Jin-Kyun Lee, Alex Zakhidov, and Priscilla G. Taylor
- Subjects
Organic electronics ,Cracking ,Materials science ,Mechanics of Materials ,Mechanical Engineering ,Boiling ,Delamination ,Organic chemistry ,General Materials Science ,Chemical change ,Dissolution ,Electronic materials - Abstract
A study was conducted to demonstrate a new approach for chemicalprocessing of organic electronic materials. It was demonstrated that the approach is based on the use of fluorous solvents, segregated hydrofluoroethers (HFE). The study also demonstrated that that processing organic electronics, using HFEs under extreme conditions, such as boiling temperatures, does not cause any dissolution, cracking, delamination,or other unfavorable physical or chemical change. The study also demonstrated that the use of fluorous solvents enables simple photolithographic patterning of organic electronic materials. It was shown that fluorous solvents are perfluorinated on very highly fluorinated liquids, which are immiscible with organic solvents and water.
- Published
- 2008
38. Control of Lasing from Bloch States in Microcavity Photonic Wires via Selective Excitation and Gain
- Author
-
Karl Leo, Andreas Mischok, Alex Zakhidov, Vadim G. Lyssenko, Robert Brückner, H. Fröb, and Publica
- Subjects
Materials science ,business.industry ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,Selective excitation ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,law.invention ,law ,0103 physical sciences ,Polariton ,Optoelectronics ,Photonics ,010306 general physics ,0210 nano-technology ,business ,Lasing threshold ,Microscale chemistry - Abstract
By adding photonic wire structures to an organic microcavity, we create an additional confinement and a Bloch-like band structure in the dispersion of periodically structured cavities. We experimentally observe spontaneous and stimulated emission from the ground and different excited discrete modes at room temperature. By changing the spatial gain distribution via a two-beam interference, we are able to directly control the laser emission from both extended and confined modes of such organic photonic wires. Both spatial distribution and dispersion exhibit coherent emission from tunable modes, which we describe with an analytical model and numerical simulations, in agreement with our measurements.
- Published
- 2015
39. Influence of bilayer resist processing on p-i-n OLEDs: towards multicolor photolithographic structuring of organic displays
- Author
-
Shrujan Kalkura, Karl Leo, Olaf R. Hild, Simone Hofmann, Alex Zakhidov, Matthias Schober, Daniel Kasemann, Simonas Krotkus, Frederik Nehm, Robby Janneck, and Sebastian Reineke
- Subjects
Materials science ,business.industry ,Propylene glycol methyl ether acetate ,Bilayer ,Nanotechnology ,law.invention ,chemistry.chemical_compound ,Hydrofluoroether ,Resist ,chemistry ,Stack (abstract data type) ,law ,OLED ,Optoelectronics ,Fluoropolymer ,Photolithography ,business - Abstract
Recently, bilayer resist processing combined with development in hydrofluoroether (HFE) solvents has been shown to enable single color structuring of vacuum-deposited state-of-the-art organic light-emitting diodes (OLED). In this work, we focus on further steps required to achieve multicolor structuring of p-i-n OLEDs using a bilayer resist approach. We show that the green phosphorescent OLED stack is undamaged after lift-off in HFEs, which is a necessary step in order to achieve RGB pixel array structured by means of photolithography. Furthermore, we investigate the influence of both, double resist processing on red OLEDs and exposure of the devices to ambient conditions, on the basis of the electrical, optical and lifetime parameters of the devices. Additionally, water vapor transmission rates of single and bilayer system are evaluated with thin Ca film conductance test. We conclude that diffusion of propylene glycol methyl ether acetate (PGMEA) through the fluoropolymer film is the main mechanism behind OLED degradation observed after bilayer processing.
- Published
- 2015
40. Fast detection and low power hydrogen sensor using edge-oriented vertically aligned 3-D network of MoS2 flakes at room temperature
- Author
-
Abhay V. Agrawal, Jiming Bao, Mahesh Kumar, Mukesh Kumar, Zhuan Zhu, Rajesh Kumar, Swaminathan Venkatesan, and Alex Zakhidov
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Passivation ,Hydrogen ,Scanning electron microscope ,Analytical chemistry ,Wide-bandgap semiconductor ,chemistry.chemical_element ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Hydrogen sensor ,0104 chemical sciences ,symbols.namesake ,Adsorption ,chemistry ,symbols ,0210 nano-technology ,Raman spectroscopy - Abstract
The increased usage of hydrogen as a next generation clean fuel strongly demands the parallel development of room temperature and low power hydrogen sensors for their safety operation. In this work, we report strong evidence for preferential hydrogen adsorption at edge-sites in an edge oriented vertically aligned 3-D network of MoS2 flakes at room temperature. The vertically aligned edge-oriented MoS2 flakes were synthesised by a modified CVD process on a SiO2/Si substrate and confirmed by Scanning Electron Microscopy. Raman spectroscopy and PL spectroscopy reveal the signature of few-layer MoS2 flakes in the sample. The sensor's performance was tested from room temperature to 150 °C for 1% hydrogen concentration. The device shows a fast response of 14.3 s even at room temperature. The sensitivity of the device strongly depends on temperature and increases from ∼1% to ∼11% as temperature increases. A detail hydrogen sensing mechanism was proposed based on the preferential hydrogen adsorption at MoS2 edge ...
- Published
- 2017
41. Field Effect Transistor Based on Solely Semiconducting Single-Walled Carbon Nanotubes for the Detection of 2-Chlorophenol
- Author
-
Elena D. Obraztsova, Alex Zakhidov, Aaron Collins, Alexander I. Chernov, Peter Walker, James Shook, Valentina A. Eremina, and Pavel V. Fedotov
- Subjects
Materials science ,business.industry ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Carbon nanotube field-effect transistor ,law.invention ,Optical properties of carbon nanotubes ,chemistry.chemical_compound ,chemistry ,2-Chlorophenol ,law ,Optoelectronics ,Field-effect transistor ,0210 nano-technology ,business - Published
- 2017
42. Photolithographic Patterning of Organic Electronic Materials
- Author
-
John DeFranco, Alex Zakhidov, Jin-Kyun Lee, Priscilla Taylor, Hon Hang Fong, Margarita Chatzichristidi, Ha Soo Hwang, Christopher Ober, and George Malliaras
- Published
- 2014
43. Molecular doping for control of gate bias stress in organic thin film transistors
- Author
-
Moritz Riede, Björn Lüssem, Karl Leo, Alex Zakhidov, Max L. Tietze, Moritz Hein, Jens Jankowski, and Publica
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Fermi level ,Transistor ,law.invention ,Pentacene ,Organic semiconductor ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Gate oxide ,Thin-film transistor ,law ,symbols ,Optoelectronics ,Thin film ,business ,Silicon oxide - Abstract
The key active devices of future organic electronic circuits are organic thin film transistors (OTFTs). Reliability of OTFTs remains one of the most challenging obstacles to be overcome for broad commercial applications. In particular, bias stress was identified as the key instability under operation for numerous OTFT devices and interfaces. Despite a multitude of experimental observations, a comprehensive mechanism describing this behavior is still missing. Furthermore, controlled methods to overcome these instabilities are so far lacking. Here, we present the approach to control and significantly alleviate the bias stress effect by using molecular doping at low concentrations. For pentacene and silicon oxide as gate oxide, we are able to reduce the time constant of degradation by three orders of magnitude. The effect of molecular doping on the bias stress behavior is explained in terms of the shift of Fermi Level and, thus, exponentially reduced proton generation at the pentacene/oxide interface. © 2014 AIP Publishing LLC.
- Published
- 2014
44. Density functional theory + U modeling of polarons in organohalide lead perovskites
- Author
-
Luisa M. Scolfaro, Alex Zakhidov, and Eric Welch
- Subjects
Condensed matter physics ,Chemistry ,Band gap ,General Physics and Astronomy ,Halide ,02 engineering and technology ,Spin–orbit interaction ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Polaron ,01 natural sciences ,Molecular physics ,lcsh:QC1-999 ,0104 chemical sciences ,Hybrid functional ,Ion ,Density functional theory ,Configuration space ,0210 nano-technology ,lcsh:Physics - Abstract
We investigate the possible formation of polarons in four organic perovskites (CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, and CH3NH3PbI2Cl1) using a density functional theory (DFT) calculations with local potentials and hybrid functionals. We show that DFT+U method with U = 8 eV predicts a correct band-gap and matches the forces on ions from hybrid calculations. We then use the DFT + U approach to study the effect of polarons, i.e. to search the configuration space and locate the lowest energy localized band gap state self-trapped hole (STH). STH configurations were found for three pure halides and one mixed halide system. Spin orbit coupling (SOC) was also taken into account and the results may be found in the supplementary material. This study focuses on the +U method; however, SOC corrections added to the DFT+U calculations also resulted in STH states in all four systems.
- Published
- 2016
45. Doped organic transistors operating in the inversion and depletion regime
- Author
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Alex Zakhidov, Karl Leo, Johann W. Bartha, Christoph Hoßbach, Max L. Tietze, Hans Kleemann, and Björn Lüssem
- Subjects
Materials science ,Silicon ,General Physics and Astronomy ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,Hardware_PERFORMANCEANDRELIABILITY ,010402 general chemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,law ,Hardware_INTEGRATEDCIRCUITS ,Microelectronics ,Multidisciplinary ,business.industry ,Transistor ,Doping ,Inversion (meteorology) ,General Chemistry ,021001 nanoscience & nanotechnology ,Chip ,Flexible electronics ,0104 chemical sciences ,Threshold voltage ,chemistry ,Optoelectronics ,0210 nano-technology ,business ,Hardware_LOGICDESIGN - Abstract
The inversion field-effect transistor is the basic device of modern microelectronics and is nowadays used more than a billion times on every state-of-the-art computer chip. In the future, this rigid technology will be complemented by flexible electronics produced at extremely low cost. Organic field-effect transistors have the potential to be the basic device for flexible electronics, but still need much improvement. In particular, despite more than 20 years of research, organic inversion mode transistors have not been reported so far. Here we discuss the first realization of organic inversion transistors and the optimization of organic depletion transistors by our organic doping technology. We show that the transistor parameters—in particular, the threshold voltage and the ON/OFF ratio—can be controlled by the doping concentration and the thickness of the transistor channel. Injection of minority carriers into the doped transistor channel is achieved by doped contacts, which allows forming an inversion layer., Inversion type transistors – which are widely used in silicon-based industries – are thought to not be obtainable in organic devices. Lüssem et al. realize the first inversion organic field-effect transistor by doping at the source and drain contacts without degrading its ON/OFF ratio.
- Published
- 2013
46. High-resolution patterning of organohalide lead perovskite pixels for photodetectors using orthogonal photolithography
- Author
-
D. A. Lyashenko, Aureliano Perez, and Alex Zakhidov
- Subjects
Organic electronics ,Materials science ,Photodetector ,Nanotechnology ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Photodiode ,Resist ,law ,Materials Chemistry ,Electrical and Electronic Engineering ,Photolithography ,Thin film ,0210 nano-technology ,Lithography ,Perovskite (structure) - Abstract
Organohalide lead perovskite (CH3NH3PbI3) is a novel material with promising applicability for visible light photo-detectors. The ability to develop perovskite photo-detector devices using a low temperature solution based process allows straightforward combinations with other materials, including traditional crystalline semiconductors, with minimal contributions to cost and process complexity. There is, however, a need for high-resolution structuring of the perovskite film to minimize cross-talk between neighboring detectors (pixels) for imaging purposes. This work presents a method to develop Ch3NH3PbI3 thin films possessing high-resolution patterning, using lithography processing with hydrofluoroether solvents. The results presented herein confirm that, unlike the majority of traditional solvents utilized in conventional photolithography, hydrofluoroethers do not adversely affect CH3NH3PbI3 films, enabling photolithographic processing. Transfer of the resist pattern is achieved using a SF6 plasma functionalization process which extracts iodine and organic components from the film, converting the perovskite into PbF2. This work also demonstrates that isolation of perovskite photodetecting pixels with a 20 μm-wide stripe of PbF2 leads to a 4.5-fold reduction in the cross-talk between neighboring pixels. It is believed that our method will facilitate simple monolithic integration of perovskite photodiodes to the silicon backplane chip utilized in active-pixel sensor and charge-coupled device applications.
- Published
- 2016
47. Orthogonal processing and patterning enabled by highly fluorinated light-emitting polymers
- Author
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Christopher K. Ober, Alex Zakhidov, Andrew B. Holmes, George G. Malliaras, Wallace W. H. Wong, Hon Hang Fong, Jin-Kyun Lee, and Yee-Fun Lim
- Subjects
Materials science ,Photoluminescence ,Light ,Polymers ,Pixel array ,chemistry.chemical_element ,Nanotechnology ,Fluorinated polymer ,Bridged Bicyclo Compounds ,General Materials Science ,Diode ,chemistry.chemical_classification ,Fluorenes ,business.industry ,Mechanical Engineering ,Polymer ,Bridged Bicyclo Compounds, Heterocyclic ,Fluorocarbon Polymers ,chemistry ,Mechanics of Materials ,Fluorine ,RGB color model ,Optoelectronics ,Polystyrenes ,Quantum Theory ,Thermodynamics ,business - Abstract
We report a family of full-color highly fluorinated light-emitting polymers. The high fluorine content allows the formation of multi-layer devices, which are shown to exhibit emission from the individual layers. A 3 x 3 photoluminescent red-green-blue (RGB) pixel array is also fabricated using standard photolithographic patterning techniques, taking advantage of the robustness of these polymers. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Published
- 2010
48. Cross-linkable molecular glasses: low dielectric constant materials patternable in hydrofluoroethers
- Author
-
Eisuke Murotani, Priscilla G. Taylor, Alex Zakhidov, Jin-Kyun Lee, Evan L. Schwartz, George G. Malliaras, Margarita Chatzichristidi, and Christopher K. Ober
- Subjects
Materials science ,Dielectric ,Capacitance ,law.invention ,Amorphous solid ,chemistry.chemical_compound ,Differential scanning calorimetry ,Hydrofluoroether ,chemistry ,Chemical engineering ,law ,Polymer chemistry ,General Materials Science ,Solubility ,Photolithography ,Micropatterning - Abstract
We report a new approach to solution-processable low-dielectric-constant (low-k) materials including photolithographic patterning of these materials in chemically benign and environmentally friendly solvents. A series of semiperfluorinated molecular glasses with styrenic substituents were successfully synthesized. These small molecular materials were thermally stable up to 400 degrees C and also exhibited an amorphous nature, which is essential to forming uniform films. Differential scanning calorimetry studies revealed that a cross-linking reaction occurred in the presence of acid, resulting in the formation of robust polymeric films. Atomic force microscopy images of the cross-linked films showed uniform and pinhole-free surface properties. Dielectric constants determined by a capacitance measurement were 2.6-2.8 (100 kHz) at ambient conditions, which are comparable to other polymeric low-k materials. The incorporation of semiperfluorinated substituents was effective in decreasing the dielectric constant; in particular, the fluorinated alkyl ether structure proved best. In addition, the fluorinated substituents contributed to good solubility in hydrofluoroether (HFE) solvents, which enabled the successful photolithographic patterning of those materials in HFEs down to a submicrometer scale.
- Published
- 2010
49. Orthogonal lithography for organic electronics
- Author
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George G. Malliaras, Ha Soo Hwang, John A. DeFranco, Priscilla G. Taylor, Alex Zakhidov, Christopher K. Ober, Margarita Chatzichristidi, Hon Hang Fong, Eisuke Murotani, and Jin-Kyun Lee
- Subjects
Organic electronics ,Materials science ,Supercritical carbon dioxide ,Nanotechnology ,Photoresist ,Chemical compatibility ,law.invention ,chemistry.chemical_compound ,Hydrofluoroether ,chemistry ,law ,Photolithography ,Lithography ,Electronic materials - Abstract
Organic electronics has recently gained attention as a new field promising cheaper, flexible, and large-scale devices. Although photolithography has proven to be a high-resolution and high-throughput patterning method with excellent registration capabilities, the emerging field of organic electronics has been largely unsuccessful in adapting this well-established method as a viable approach to patterning. Chemical compatibility issues between organic materials and the processing solvents and chemicals required by photolithography have been the main problem. This challenge has led us to identify a set of non-damaging processing solvents and to develop alternative imaging materials in order to extend photolithographic patterning methods to organic electronics. We have identified supercritical carbon dioxide and hydrofluoroether (HFE) solvents as chemically benign to organic electronic materials and which are also suitable as processing solvents. We refer to these solvents as orthogonal in that they do not substantially interact with traditional aqueous and organic solvents. Multi-layered devices are easily realized by exploiting this orthogonality property; subsequent layers are deposited and patterned without damaging or otherwise adversely affecting previously deposited underlying layers. We have designed and synthesized novel photoresists, which are processible in these benign solvents.
- Published
- 2010
50. Acid-sensitive semiperfluoroalkyl resorcinarene: an imaging material for organic electronics
- Author
-
George G. Malliaras, Andrew B. Holmes, Christopher K. Ober, Ha Soo Hwang, Alex Zakhidov, Priscilla G. Taylor, Hon Hang Fong, John A. DeFranco, Jin-Kyun Lee, and Margarita Chatzichristidi
- Subjects
Organic electronics ,Hydrocarbons, Fluorinated ,Chemistry ,Phenylalanine ,Inorganic chemistry ,Nanotechnology ,General Chemistry ,Resorcinarene ,Electrochemistry ,Biochemistry ,Catalysis ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Hydrofluoroether ,Acid sensitive ,Calixarene ,Solubility ,Calixarenes ,Electronics ,Electronic materials - Abstract
An acid-sensitive semiperfluoroalkyl resorcinarene was synthesized, and its lithographic properties were evaluated. Its solubility in segregated hydrofluoroether solvents enables the patterning of delicate organic electronic materials.
- Published
- 2008
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