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The appropriate hosts of emitting layers (EMLs) play an important role in determining the overall performance of solution-processed phosphorescent organic light emitting diodes (PhOLEDs). We have investigated the effect of three species of host molecules, 1,3-bis(carbazol-9-yl)benzene (mCP), 10-(4-(5,5dimethylbenzofuro[3,2-c]acridin-13(5H)-yl)phenyl)-10-phenylanthracen-9(10H)-one (DpAn-5BzAc) and poly(9-vinylcarbazole) (PVK), on the performance of solution-processed blue and yellow PhOLEDs. We have found that compared to the widely used single-host EMLs, the devices using the binary blend of mCP: DpAn5BzAc as hosts, can achieve more efficient optoelectrical characteristics. The maximum current efficiencies of 11.84 and 16.61 have been realized for blue and yellow OLEDs, respectively. The superior electroluminescence performance for binary blend host-based PhOLEDs was attributed to the enhanced charge carrier balance and multi-component miscibility, which has a dramatic influence on the morphology of the emissive layer. These results demonstrate the great potential of the multi-hosts in solution-processed organic optoelectronic devices. The development of complementary colour OLEDs with blue and yellow can provide a simple approach to fabricate solution-processed white PhOLEDs.

A Cu2O film is prepared on a flexible polyethylene terephthalate substrate for a bending sensor using the spin–spray method, a facile and low-environmental-load solution process. The Cu2O bending sensor shows high sensitivity and high resolution not only over a wide range of curvatures (0 < κ < 0.21 mm–1) but also for very small curvature changes (Δκ = ∼ 0.03 mm–1). The bending response of the sensor exhibited a curvature change of high linearity with a good gauge factor (18.2) owing to the grain-boundary resistance and piezoresistive effects of the fabricated Cu2O film. In addition, the sensor possesses good repeatability, stability, and long-term (>30 days) and mechanical fatigue durability (1000 bending–release cycles). The sensor is capable of detailed monitoring of large- and small-scale human motions, such as finger bending, wrist bending, nodding, mouth opening/closing, and swallowing. In addition, excellent stability and repeatability of the monitoring performance is observed over a wide range of motion angles and speeds. All of these results demonstrate the potential of the flexible bending sensor based on the Cu2O film as a candidate for healthcare monitoring and wearable electronics.

Due to their high photoelectric conversion efficiency (PCE) and low-cost fabrication process, n-type silicon (n-Si)/poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid heter...

Low-cost inorganic solution processing for oxide semiconductor thin-film transistors (TFTs) is crucial for developing next-generation cost-effective, ubiquitous, and flexible electronics, and the d...

Epitaxial La-doped BaSnO3 (BLSO) thin films were fabricated on a SrTiO3 (100) substrate by a cost-efficient and scalable solution deposition method. Microstructures and optoelectronic properties of...

Developing solution-processable deep-blue emitters for organic light-emitting diodes (OLEDs) is still a challenging task. In this context, two new solution-processable deep-blue emitters, N, N-diphenyl-4���-(1-(3-(trifluoromethyl)phenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)-[1,1���-biphenyl]-4-amine(4-PIMCFTPA) and 4���-(4,5-diphenyl-1-(3-(trifluoromethyl)phenyl)-1H-imidazol-2-yl)-N,N-diphenyl-[1,1���-biphenyl]-4-amine (4-BICFTPA), were successfully designed and synthesized by incorporating phenanthroimidazole (PI)/diphenylimidazole (BI)-triphenylamine (TPA), which is functional at the N1 position of the imidazole, with Ph-mCF3. The thermal, photophysical, and electrochemical properties of both fluorophores were systematically explored. These fluorophores showed a deep-blue emission in the solution as well as in the solid state. The highest occupied molecular orbital (HOMO) ��� lowest unoccupied molecular orbital (LUMO) energy level of the fluorophores was calculated using electrochemical studies and compared with the theoretical calculation [the density functional theory (DFT)]. The asymmetrically twisted conformation of 4-PIMCFTPA between PI-TPA efficiently showed a high photoluminescence quantum yield. OLED (undoped and doped) devices were fabricated with the newly synthesized emitters, and 4-PIMCFTPA demonstrated better electroluminescence (EL) performance than the BI-based emitter. Thus, the OLED based on 4-PIMCFTPA (1 wt% in the CBP host) had the best EL performance, with a maximum external quantum efficiency 1.7% and CIE coordinates of (0.17, 0.06).

Polytriarylamine (PTAA) is a promising yet trending organic semiconductor material in which has unique characteristics that are low-cost fabrication, flexible and stable in room condition. The unique characteristic of PTAA thin films have attracted researchers to explore more on its ability as future green technology solutions. In this works, the effect of annealing temperature towards PTAA thin films are focused. PTAA thin films is fabricated by solution processed technique and sintered onto the glass substrate by spin coating method. The spin coating speed are 1000 RPM to 5000 RPM. The PTAA thin films are further annealed for an hour with temperatures of 80 oC, 120 oC and 150 oC. It is shown that grain size of thin films are increasing as the temperature increased based on XRD analysis. As for 1000 to 5000 RPM, the highest grain size obtain are 26.46 nm, 31.34 nm, 37.19 nm, 39.96 nm and 42.72 nm, respectively. Optical characteristic also reveals that band gap energy value is perpendicular to the increasing in temperature obtain from the UV-Vis spectrum. The results strongly show that annealing temperature had significantly affected both structural and optical properties of PTAA thin films.

The surface Ga content for a CIGSe absorber was closely related to variation in the open-circuit voltage (VOC), while it was generally low on a CIGSe surface fabricated by two-step selenization. In this work, a solution-processed surface treatment based on spin-coating GaCl3 solution onto a CIGSe surface was applied to increase the Ga content on the surface. XPS, XRD, Raman spectroscopy, and band gap extraction based on the external quantum efficiency response demonstrated that GaCl3 post deposition treatment (GaCl3-PDT) can be used to enhance the Ga content on the surface of a CIGSe absorber. Meanwhile, a solution-processed surface treatment with KSCN (KSCN-PDT) was employed to form a transmission barrier for holes by moving the valence band maximum downward and decreasing the interface recombination between the CdS and CIGSe layers. Admittance spectroscopy results revealed that deep defects were passivated by GaCl3-PDT or KSCN-PDT. By applying the combination of GaCl3-PDT and KSCN-PDT, a champion device was realized that exhibited an efficiency of 13.5% with an improved VOC of 610 mV. Comparing the efficiency of the untreated CIGSe solar cells (11.7%), the CIGSe device efficiency with GaCl3-PDT and KSCN-PDT exhibited 15% enhancement.

We present a strategy for developing an in-depth understanding of the synergy between triplet energy (ET) and structural composition of molecular hosts for organic light-emitting diodes (OLEDs) ini...

In this research, a heterostructure of the CuO-ZnO-based solar cells has been fabricated using low-cost, earth-abundant, non-toxic metal oxides by a low-cost, low-temperature spin coating technique...

Tin(IV) phthalocyanines (SnPcs) are promising candidates for low-cost organic electronic devices, and have been employed in organic photovoltaics (OPVs) and organic thin-film transistors (OTFTs). However, they remain relatively understudied compared to their silicon phthalocyanine (SiPc) analogues. Previously, we reported the first solution-processed SnPc semiconductors for OTFTs and OPVs; however, the performances of these derivatives were unexpected. Herein to further study the behavior of these derivatives in OPVs and OTFTs, we report the synthesis along with optical and thermal characterization of seven axially substituted (OR)2-SnPcs, five of which were synthesized for the first time. Density functional theory (DFT) was used to predict charge-carrier mobilities for our materials in their crystal state. The application of these SnPcs as ternary additives in poly(3-hexylthiophene) (P3HT)/phenyl-C61-butyric acid methyl ester (PC61BM) OPVs and as semiconductors in solution-processed n-type OTFTs was also investigated. When employed as ternary additives in OPVs, all (OR)2-SnPcs decreased the power conversion efficiency, open-circuit voltage, short-circuit current, and fill factor. However, in OTFTs, four of the seven materials exhibited greater electron field-effect mobility with similar threshold voltages compared to their previously studied SiPc analogues. Among these SnPcs, bis(triisobutylsilyl oxide) SnPc displayed the greatest electron field-effect mobility of 0.014 cm2 V-1 s-1, with a threshold voltage of 31.4 V when incorporated into OTFTs. This difference in electrical performance between OTFT and OPV devices was attributed to the low photostability of SnPcs.

Sb2Se3 is a promising absorber material for thin-film solar cells owing to its earth-abundant and non-toxic constituents, superior optoelectronic properties, and unique one-dimensional crystal structure. To further increase the power conversion efficiency of the Sb2Se3, we fabricated an n-i-p structure by integrating a solution-processed NiOx hole-transport layer (HTL) into Sb2Se3 solar cells to enhance the carrier collection. In this study, we systematically screen the thickness of NiOx HTL and demonstrate an improved average power conversion efficiency from 6.12% to 7.15% with a 50 nm NiOx HTL. The mechanism associated with the improved device performance was characterized through the microstructure of the material, device physics, and interface electronic behaviors. It is also shown that the low-cost and scalable solution-processed NiOx HTL can improve device stability under an accelerated stress test. Thus, this work paves a way to further improve the performance of antimony chalcogenides-based solar cells via tailoring the inorganic HTL.

Carrier-selective contacts, especially in electron-selective contact (ESC), between the metal electrodes and the crystalline silicon (c-Si) substrates play a pivotal section in promoting the power ...

As one of the promising next-generation electronics, brain-inspired synaptic resistive random access memory (RRAM) devices with stacked solution-processed (SP) spin-coated resistive switching (RS) ...

All-solution-processed multilayered white polymer light-emitting diodes (WPLEDs) are promising candidates for low-cost and large-area flexible full-color flat-panel displays and solid-state lightin...

Fully solution-processed, large-area, electrical double-layer transistors (EDLTs) are presented by employing lead sulfide (PbS) colloidal quantum dots (CQDs) as active channels and Ti3C2Tx MXene as...

The outstanding properties of perovskites have attracted huge attention in optoelectronic applications. However, the current study mainly focuses on small-area single-layer perovskite films. Surfac...

Due to the desirable film-forming ability and morphological stability, a new bipolar Ir(iii) complex FMPPHC can act as a blue emitter and a host sensitizing efficient saturated red light in wet-process emitting systems.

High performance solution processable thermally activated delayed fluorescence (TADF) emitters are of huge importance in the development of organic light-emitting diodes (OLEDs). In this article, two solution processable D3–A star-shaped TADF emitters, namely TATC-TRZ and TATP-TRZ, with different flexible alkyl and rigid phenyl side chains are developed. Both emitters show similar photophysical properties and obvious TADF characteristics with a sub-micro second delayed lifetime of 0.6 μs for TATC-TRZ and 0.4 μs for TATP-TRZ while the flexible alkyl chain ensures TATC-TRZ with superior film forming ability and morphological stability compared to TATP-TRZ. Owing to such advantages, solution processed non-doped OLEDs based on TATC-TRZ secure a high maximum external quantum efficiency (EQEmax) of 7.5% and current efficiency (CEmax) of 19.9 cd A−1, respectively, which is much higher than that of TATP-TRZ with EQEmax of 2.8% and CEmax of 7.4 cd A−1. This work demonstrates the effectiveness of a flexible alkyl tail on the performance of solution-processed devices.

The interest in investigating hollow core–shell nanostructures was stimulated by their intrinsic advantage in light absorption and photocarrier separation for promising applications in photoelectrochemical devices. Here, SnO2@TiO2 core–shell hierarchical tubular structure was designed and prepared via a low-temperature solution route using carbon nanofibers as templates. The heterostructure consists of SnO2 nanotubes and TiO2 nanocones, which facilities photocarrier separation and transport by built-in electric field at their interface, and direct transport path served by SnO2 nanotubes. The large specific surface area was also believed to contribute to improve performance by providing more active sites for chemical reactions. After assembling into a photoelectrochemical-type ultraviolet photodetector, the detector exhibits a high short-circuit photocurrent density of 870 μA cm–2 under ultraviolet illumination (λ = 365 nm) of 35 mW cm–2 without bias voltage. The photosensitivity can reach up to 3781, and the feature response time was in microseconds, 33 ms for rise process and 13 ms for decay process. It is believed that this structure with combined advantageous features is extendable to other photoelectrochemical cases, such as dye-sensitized solar cells and artificial photosynthesis.

The development of advanced organic devices has already broken the limit of one-component material constitution, seeking for integration of multiple components to achieve new features. It is well-k...

Through‐space charge transfer (TSCT) polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect, different from conventional luminescent polymers with conjugated donor‐acceptor structure and through‐bond charge transfer emission. Their emission comes from the intramolecular charge transfer by through‐space pathway because the donor and acceptor segments are spatially proximate to each other in each repeating unit but are physically separated by nonconjugated polymer backbone. In this review, recent advances in TSCT polymers with linear, bottlebrush, and dendritic architectures are presented, with the focus on their molecular design, photophysical behavior, and device performance. We hope that this review shall provide a useful insight of new luminescent polymers with TSCT effect for use in solution‐processed organic light‐emitting diodes.

The sonochemical synthesis of CsPbBr3 perovskite nanocrystals (PNCs) is an attractive method for the large-scale synthesis and low-cost production of PNC at low temperature; however, there are no r...

Photoerasable memories based on the organic field-effect transistor (OFET) have aroused great interest due to the advantages and potential applications, such as the erasure of confidential informat...

Molybdenum disulfide (MoS2) is an emerging two-dimensional (2D) material for next-generation optoelectronic and energy storage devices. Although various efforts have been made to understand the pho...

The highly flexible and stretchable polymer elastomer having a low dielectric constant (k ∼ 2.6), called poly(dimethylsiloxane) (PDMS), is a promising gate dielectric material for solution-processe...

Simple solution-processed structures of organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) have been demonstrated, but their efficiency and roll-off are ...

Zinc oxide (ZnO) and Al-doped ZnO are important optoelectronic materials. ZnO in particular has a wide band gap (Eg ~ 3.3 eV at 300 K), large exciton binding energy (~66 meV) and especially for the variety of methods by which it can be processed. Moreover, ZnO is readily able to alloy with other metals in the oxide form and has a lattice that can facilitate interstitial doping using several metals, including Al and Sn. This gives ZnO a key role in optoelectronics, metal oxide thin films and thin film transistor (TFT) technologies. We demonstrate that crystalline, epitaxial-like and highly ordered ZnO and Al:ZnO (AZO) quasisuperlattice thin films can be achieved from a precursor liquid at relatively low temperature via spin-coating, which crystallize with near epitaxy with a pronounced c-plane texture. We also show the visible and near-infra red (VIS-NIR) light spectroscopy of ZnO and Al:ZnO multi-layered thin film structures grown on oxidized silicon substrates. We show measurements demonstrating sub-band optical pumping of AZO QSLs that enable significant photoconductivity. In AZO QSLs, conduction band electrons from valence band pumping at incident irradiation > Eg, are not required to initiate or enhance photoconductivity, and PL data indicate a donor level that enable enhance sub-band photoconductivity even up to bias voltages of 200 V. Photoexcitation with a 532 nm source efficiently pumps the AZO conduction band without increasing the density of electron-holes in the valence band, minimizing field-driven recombination and enabling significant photoconductance over wide voltage ranges. Density functional theory analysis on ZnO systems with Al-doping configurations of ~2% indicate that interstitial doping is required to generate a density of states that corroborates the proposed donor level to enable the photoconductive properties seen in this work. References [1] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano and H. Hosono, Nature 432, 488 (2004). [2] T. Kamiya, K. Nomura and H. Hosono, Sci. Tech. Adv. Mater. 11, 044305 (2010). [3] R. A. Street, Adv. Mater. 21, 2007 (2009). [4] H. Lingling, H. Dedong, C. Zhuofa, C. Yingying, W. Jing, Z. Nannan, D. Junchen, Z. Feilong, L. Lifeng, Z. Shengdong, Z. Xing and W. Yi, Jpn. J. Appl. Phys 54, 04DJ07 (2015). [5] C. Glynn and C. O'Dwyer, Adv. Mater. Interfaces 4, 1600610 (2017). [6] D. Buckley, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, J. Vac. Sci. Technol. A, 35, 061517 (2017). [7] D. Buckley, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, ECS Trans., 77, 99 (2017). [8] D. Buckley, R. McCormack and C. O'Dwyer, J. Phys. D: Appl. Phys., 50, 16TL01 (2017). [9] D. Buckley, R. McCormack, D. McNulty, V. Z. Zubialevich, P. J. Parbrook and C. O'Dwyer, ECS Trans., 77, 75 (2017).

Two-dimensional (2D) semiconductor nanocrystals processed from solution have become an attractive material platform for the development of optoelectronic devices. The synergy of the 2D charge carri...

A new molecular precursor for Cu2ZnSnS4 (CZTS) has been explored for the fabrication of efficient superstrate type solar cells with all solution processed functional layers at low temperature. The CZTS film made at low temperature (250 °C), without sulfurization was employed in the heterojunction device with a thin interface layer of CdS and the one-step hydrothermally processed rutile TiO2 nanorod arrays. The quality of the CZTS film was optimized by varying the composition of Cu and Zn in the precursor solution. Initial devices with (FTO/TiO2/CdS/CZTS/Au) structure exhibited the power conversion efficiency up to 1.04%, on par with the best in the relevant literature.

In this article, laser scanning annealing is used for the fabrication of solution-processed tungsten–zinc–tin-oxide thin-film transistors (WZTO TFTs) with low temperatures and fast processing. The ...

Very high power conversion efficiencies (PCEs) have been demonstrated by multijunction cells made of epitaxial III–V semiconductors; but they are too expensive to manufacture for terrestrial applic...

Light management strategies can increase the efficiency of perovskite single-junction and tandem solar cells. In this study, we present perovskite solar cells deposited on different shallow nanotex...