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1. Structural Dynamics of Polymer:Non-Fullerene Organic Solar Cell Blends: A Neutron Spectroscopy Perspective

Author

Zbiri, Mohamed, Gilhooly-Finn, Peter A., Fouquet, Peter, Nielsen, Christian B., and Guilbert, Anne A. Y.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

Organic solar cells (OSCs) based on ADA-type (acceptor-donor-acceptor) non-fullerene acceptors (NFAs) exhibit improved power conversion efficiency (PCE) compared to the conventional fullerene-based analogues. The optoelectronic properties of OSC active layer blends are correlated to their underlying structural dynamics and therefore influence the device performance. Using synergistically different neutron spectroscopy techniques, we studied the dynamics of binary and ternary blends made of the NFAs O-IDTBR and O-IDFBR and the regioregular donor polymer P3HT. Deuteration was considered for a contrast variation purpose. In addition to shedding light on the miscibilty and alloying characters of the blends, a main outcome of this work is the evidenced similar dynamical response of the blend components. This finding is in contrast with our previous neutron spectroscopy and molecular dynamics studies of the fullerene-based blend P3HT:PCBM, where we highlighted distinct behaviors of P3HT and PCBM in terms of the vitrification/frustration of P3HT and the plasticization of PCBM by P3HT upon blending. Alike P3HT vitrification is not presently observed. The absence or the weak vitrification evidenced here is in line with recent reports and is likely related to the improved PCE exhibited by the ADA-type NFA-based OSCs.

Published
2022
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3. Quantitative insights into the phase behaviour and miscibility of organic photovoltaic active layers from the perspective of neutron spectroscopy

Author

Zbiri, Mohamed, Finn, Peter A., Nielsen, Christian B., and Guilbert, Anne A. Y.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

We present a neutron spectroscopy based method to study quantitatively the partial miscibility and phase behaviour of an organic photovoltaic active layer made of conjugated polymer:small molecule blends, presently illustrated with the regio-random poly(3-hexylthiophene-2,5-diyl) and fullerene [6,6]-Phenyl C$_{61}$ butyric acid methyl ester (RRa-P3HT:PCBM) system. We perform both inelastic neutron scattering and quasi-elastic neutron scattering measurements to study the structural dynamics of blends of different compositions enabling us to resolve the phase behaviour. The difference of neutron cross sections between RRa-P3HT and PCBM, and the use of deuteration technique, offer a unique opportunity to probe the miscibility limit of fullerene in the amorphous polymer-rich phase and to tune the contrast between the polymer and the fullerene phases, respectively. Therefore, the proposed approach should be universal and relevant to study new non-fullerene acceptors that are closely related - in terms of chemical structures - to the polymer, where other conventional imaging and spectroscopic techniques present a poor contrast between the blend components.

Published
2021
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4. Effect of substituting non-polar chains with polar chains on the structural dynamics of small organic molecule and polymer semiconductors

Author

Guilbert, Anne A. Y., Parr, Zachary S., Kreouzis, Theo, Woods, Duncan J., Sprick, Reiner S., Abrahams, Isaac, Nielsen, Christian B., and Zbiri, Mohamed

Subjects
Condensed Matter - Materials Science, Condensed Matter - Soft Condensed Matter
Abstract

The processability and optoelectronic properties of organic semiconductors can be tuned and manipulated via chemical design. The substitution of the alkyl side chains by oligoethers has recently been successful for applications such as bioelectronic sensors and photocatalytic water-splitting. The carbon-oxygen bond in oligoethers is likely to render the system softer and more prone to dynamical disorder that can be detrimental to charge transport for example. We use neutron spectroscopy, X-Ray diffraction (XRD), differential scanning calorimetry (DSC) and polarized optical microscopy to study the effect of the substitution of n-hexyl (Hex) by triethylene glycol (TEG) on the structural dynamics of two organic semiconductors: a phenylene-bithiophene-phenylene (PTTP) molecule and a fluorene-co-dibenzothiophene (FS) polymer. Counterintuitively, inelastic neutron scattering (INS) reveals a softening of the modes of PTTP and FS with Hex side chains, pointing towards an increased dynamical disorder in these systems. However, T-dependent X-Ray and neutron diffraction, INS and DSC evidence an extra reversible transition close to room temperature (RT) for PTTP with TEG side chains. The observed transition, not accompanied by a change in birefringence, can also be observed by quasi-elastic neutron scattering. A fastening of the TEG side chains dynamics is observed in the case of PTTP and not FS. We therefore assign this transition to the melt of the TEG side chains which are promoting dynamical order at RT, but if crystallising, may introduce an extra reversible structural transition above RT leading to thermal instabilities. A deeper understanding of side chain polarity and structural dynamics can help guide materials design and navigate the intricate balance between electronic charge transport and aqueous swelling, sought for a number of emerging organic electronic and bioelectronic applications.

Published
2021
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5. Fragment Graphical Variational AutoEncoding for Screening Molecules with Small Data

Author

Armitage, John, Spalek, Leszek J., Nguyen, Malgorzata, Nikolka, Mark, Jacobs, Ian E., Marañón, Lorena, Nasrallah, Iyad, Schweicher, Guillaume, Dimov, Ivan, Simatos, Dimitrios, McCulloch, Iain, Nielsen, Christian B., Conduit, Gareth, and Sirringhaus, Henning

Subjects
Physics - Data Analysis, Statistics and Probability, Condensed Matter - Materials Science, Computer Science - Machine Learning, Physics - Applied Physics, Physics - Computational Physics, Statistics - Machine Learning
Abstract

In the majority of molecular optimization tasks, predictive machine learning (ML) models are limited due to the unavailability and cost of generating big experimental datasets on the specific task. To circumvent this limitation, ML models are trained on big theoretical datasets or experimental indicators of molecular suitability that are either publicly available or inexpensive to acquire. These approaches produce a set of candidate molecules which have to be ranked using limited experimental data or expert knowledge. Under the assumption that structure is related to functionality, here we use a molecular fragment-based graphical autoencoder to generate unique structural fingerprints to efficiently search through the candidate set. We demonstrate that fragment-based graphical autoencoding reduces the error in predicting physical characteristics such as the solubility and partition coefficient in the small data regime compared to other extended circular fingerprints and string based approaches. We further demonstrate that this approach is capable of providing insight into real world molecular optimization problems, such as searching for stabilization additives in organic semiconductors by accurately predicting 92% of test molecules given 69 training examples. This task is a model example of black box molecular optimization as there is minimal theoretical and experimental knowledge to accurately predict the suitability of the additives.

Published
2019

6. Mapping Microstructural Dynamics up to the Nanosecond of the Conjugated Polymer P3HT in the Solid State

Author

Guilbert", Anne A. Y., Zbiri", Mohamed, Finn, Peter A., Jenart, Maud, Fouquet, Peter, Cristiglio, Viviana, Frick, Bernhard, Nelson, Jenny, and Nielsen, Christian B.

Subjects
Condensed Matter - Materials Science
Abstract

We present a detailed study of the structure-dynamics relationship of regio-regular and regio-random PEHT using different neutron scattering techniques. Deuteration is employed to modulate the coherent and incoherent cross-sections, allowing particularly to access both self-motions and collective dynamics of the materials. The measurements are underpinned by extensive quantitative calculations using classical MD, as well as first principles quantum chemistry. MD reproduced well the main structural features and slow motions, and shed light on differences in collective dynamics between Q-values linked with the $\pi-\pi$ stacking and the lamellar stacking, with the crystalline phase being the most impacted. On the other hand MD led to a limited description of molecular vibrations. In this context, first principles molecular calculations described well the high-energy vibrational features ( $>$ 900 cm$^{-1}$ ), while periodic calculations allowed to better describe the low- and mid-energy vibrational ranges ( 200-900 cm$^{-1}$ ). The mid-energy range is predominantly associated with both intra-molecular and inter-molecular mode coupling, which encloses information about both the polymer conformation and the polymer packing at short range. One of the outcomes of this study is the validation of the common assumption made that RRa-P3HT is a good approximation for the amorphous phase of RR-P3HT at the macroscopic level. The present work helps to clarify unambiguously the latter point which has been largely overlooked in the literature. We highlight the importance to complement optical spectroscopy techniques with inelastic neutron scattering. The latter offering the advantage of being insensitive to the delocalized $\pi$-electron system, and thus enabling to infer relevant quantities like conjugation lengths, for instance, impacting properties of conjugated polymer., Comment: Featured as ACS Editors' Choice. Featured on the Cover of the December 10, 2019 issue of Chemistry of Materials

Published
2019
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7. Tuning the effective spin-orbit coupling in molecular semiconductors

Author

Schott, Sam, McNellis, Erik R., Nielsen, Christian B., Chen, Hung-Yang, Watanabe, Shun, Tanaka, Hisaaki, McCulloch, Iain, Takimiya, Kazuo, Sinova, Jairo, and Sirringhaus, Henning

Subjects
Condensed Matter - Materials Science
Abstract

The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven diffi- cult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g -shifts to spin-lattice relaxation times over four orders of magnitude, from 200 {\mu}s to 0.15 {\mu}s, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems., Comment: Accepted for publication in Nature Communications

Published
2017
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8. Side chain engineering in indacenodithiophene-co-benzothiadiazole and its impact on mixed ionic-electronic transport properties

Author

Holzer, Isabelle, Lemaur, Vincent, Wang, Meng, Wu, Hanyan, Zhang, Lu, Marcial-Hernandez, Raymundo, Gilhooly-Finn, Peter, Cavassin, Priscila, Hoyas, Sebastien, Meli, Dilara, Wu, Ruiheng, Paulsen, Bryan D., Strzalka, Joseph, Liscio, Andrea, Rivnay, Jonathan, Sirringhaus, Henning, Banerji, Natalie, Beljonne, David, Fabiano, Simone, Nielsen, Christian B., Holzer, Isabelle, Lemaur, Vincent, Wang, Meng, Wu, Hanyan, Zhang, Lu, Marcial-Hernandez, Raymundo, Gilhooly-Finn, Peter, Cavassin, Priscila, Hoyas, Sebastien, Meli, Dilara, Wu, Ruiheng, Paulsen, Bryan D., Strzalka, Joseph, Liscio, Andrea, Rivnay, Jonathan, Sirringhaus, Henning, Banerji, Natalie, Beljonne, David, Fabiano, Simone, and Nielsen, Christian B.

Abstract

Organic semiconductors are increasingly being decorated with hydrophilic solubilising chains to create materials that can function as mixed ionic-electronic conductors, which are promising candidates for interfacing biological systems with organic electronics. While numerous organic semiconductors, including p- and n-type materials, small molecules and polymers, have been successfully tailored to encompass mixed conduction properties, common to all these systems is that they have been semicrystalline materials. Here, we explore how side chain engineering in the nano-crystalline indacenodithiophene-co-benzothiadiazole (IDTBT) polymer can be used to instil ionic transport properties and how this in turn influences the electronic transport properties. This allows us to ultimately assess the mixed ionic-electronic transport properties of these new IDTBT polymers using the organic electrochemical transistor as the testing platform. Using a complementary experimental and computational approach, we find that polar IDTBT derivatives can be infiltrated by water and solvated ions, they can be electrochemically doped efficiently in aqueous electrolyte with fast doping kinetics, and upon aqueous swelling there is no deterioration of the close interchain contacts that are vital for efficient charge transport in the IDTBT system. Despite these promising attributes, mixed ionic-electronic charge transport properties are surprisingly poor in all the polar IDTBT derivatives. Albeit a "negative" result, this finding clearly contradicts established side chain engineering rules for mixed ionic-electronic conductors, which motivated our continued investigation of this system. We eventually find this anomalous behaviour to be caused by increasing energetic disorder in the polymers with increasing polar side chain content. We have investigated computationally how the polar side chain motifs contribute to this detrimental energetic inhomogeneity and ultimately use the learnings to propose, Funding Agencies|European Commission [964677, 2.5020.11]; European Commission Horizon 2020 Future and Emerging Technologies (FET) [1117545]; Walloon Region; National Science Foundation [DMR-1751308]; NSF [DE-AC02-06CH11357]; DOE Office of Science by Argonne National Laboratory

Published
2024
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9. Single-Component Electroactive Polymer Architectures for Non-Enzymatic Glucose Sensing

Author

Kousseff, Christina J. (author), Wustoni, Shofarul (author), Silva, Raphaela K.S. (author), Lifer, Ariel (author), Savva, A. (author), Frey, Gitti L. (author), Inal, Sahika (author), Nielsen, Christian B. (author), Kousseff, Christina J. (author), Wustoni, Shofarul (author), Silva, Raphaela K.S. (author), Lifer, Ariel (author), Savva, A. (author), Frey, Gitti L. (author), Inal, Sahika (author), and Nielsen, Christian B. (author)

Abstract

Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC-based sensors rely predominantly on the use of composite matrices to enable stimuli-responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non-enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT-PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT-PBA and molecularly imprinted PEDOT-PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non-imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly., Bio-Electronics

Published
2024
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10. Single‐Component Electroactive Polymer Architectures for Non‐Enzymatic Glucose Sensing.

Author

Kousseff, Christina J., Wustoni, Shofarul, Silva, Raphaela K. S., Lifer, Ariel, Savva, Achilleas, Frey, Gitti L., Inal, Sahika, and Nielsen, Christian B.

Subjects
CONDUCTING polymers, IMPRINTED polymers, GLUCOSE, POLYMER films, SENSOR arrays, BIOMATERIALS
Abstract

Organic mixed ionic‐electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC‐based sensors rely predominantly on the use of composite matrices to enable stimuli‐responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non‐enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT‐PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT‐PBA and molecularly imprinted PEDOT‐PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non‐imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Charge-Transfer State Dynamics Following Hole and Electron Transfer in Organic Photovoltaic Devices

Author

Bakulin, Artem A., Dimitrov, Stoichko D., Rao, Akshay, Chow, Philip C. Y., Nielsen, Christian B., Schroeder, Bob C., McCulloch, Iain, Bakker, Huib J., Durrant, James R., and Friend, Richard H.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

The formation of bound electron-hole pairs, also called charge-transfer (CT) states, in organic-based photovoltaic devices is one of the dominant loss mechanisms hindering performance. While CT state dynamics following electron transfer from donor to acceptor have been widely studied, there is not much known about the dynamics of bound CT states produced by hole transfer from the acceptor to the donor. In this letter, we compare the dynamics of CT states formed in the different charge-transfer pathways in a range of model systems. We show that the nature and dynamics of the generated CT states are similar in the case of electron and hole transfer. However the yield of bound and free charges is observed to be strongly dependent on the HOMOD-HOMOA and LUMOD-LUMOA energy differences of the material system. We propose a qualitative model in which the effects of static disorder and sampling of states during the relaxation determine the probability of accessing CT states favourable for charge separation.

Published
2013
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14. Urinary Dipstick Is Not Reliable as a Screening Tool for Albuminuria in the Emergency Department—A Prospective Cohort Study

Author

Nielsen, Christian B., Birn, Henrik, Brandt, Frans, and Kampmann, Jan D.

Subjects
Proteinuria, Emergency department, urinary dipstick, proteinuria, albuminuria, screening, kidney disease, emergency department, Clinical Biochemistry, parasitic diseases, Screening, Albuminuria, Kidney disease, urologic and male genital diseases, Urinary dipstick
Abstract

Albuminuria is a sensitive marker for renal dysfunction. Urinary dipstick tests are frequently used to screen for urinary abnormalities in the emergency department (ED). The aim of this prospective cohort study is to evaluate the usefulness of urinary dipstick testing as a screening tool for albuminuria in the ED setting and to determine the persistency of albuminuria identified in the acute setting. Urinary dipstick tests and spot urine samples were obtained simultaneously for analysis of the urinary albumin-creatinine ratio (ACR). Participants with positive dipsticks for protein were invited for a second urinalysis four to six weeks after admission. The study included 234 patients admitted to the ED. Urinalysis was performed on 178 patients of which 46% (n = 82) had positive urinary dipstick tests for proteinuria. The sensitivity and specificity of the dipstick test were low (72.7% and 55.7% respectively) when compared to the ACR. Of the 82 patients with positive dipsticks at admission, 35 were available for follow-up. We observed a significant reduction in ACR at follow-up when compared to ACR at admission (p = 0.004). This paper concludes that urinary dipstick tests are not a reliable means to screen for albuminuria in the ED setting.

Published
2022
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19. Thermal stabilisation of squaraine dyes by encapsulation in a rotaxane

Author

Bak, Helle Ø., Nielsen, Bjarne E., Petersen, Michael Å., Jeppesen, Anne, Brock-nannestad, Theis, Nielsen, Christian B. O., Pittelkow, Michael, Bak, Helle Ø., Nielsen, Bjarne E., Petersen, Michael Å., Jeppesen, Anne, Brock-nannestad, Theis, Nielsen, Christian B. O., and Pittelkow, Michael

Published
2020

20. Intramolecular hydrogen bonding and hydrogen atom abstraction in gas-phase aliphatic amine radical cation

Author

Nielsen, Christian B. and Hammerum, Steen

Subjects
Hydrogen bonding -- Research, Nitrogen compounds -- Atomic properties, Chemicals, plastics and rubber industries
Abstract

The intramolecular hydrogen atom abstraction by the nitrogen atom in isolated aliphatic amine radical cations is examined. The hydrogen atom abstraction yields distonic isomers of the molecular ions, which is the initial step in the skeletal rearrangement reactions that often precede the fragmentation of metastable amine radical cations.

Published
2005

21. Synthesis and characterization of water-soluble phenylene-vinylene-based singlet oxygen sensitizers for two-photon excitation

Author

Nielsen, Christian B., Johnsen, Mette, Arnbjerg, Jacob, Pittelkow, Michael, McIlroy, Sean P., Ogilby, Peter R., and Jorgensen, Mikkel

Subjects
Active oxygen -- Chemical properties, Biological sciences, Chemistry
Abstract

The synthesis and characterization of water-soluble singlet oxygen sensitizers with a phenylene-vinylene motif is presented. Sensitizers are synthesized with ionic as well as nonionic substituents to achieve water solubility.

Published
2005

22. Delayed dissociation of photoexcited porphyrin cations in a storage ring: Determination of triplet quantum yields

Author

Nielsen, Christian B., Forster, James S., Ogilby, Peter R., and Nielsen, Steen Brondsted

Subjects
Dissociation -- Observations, Porphyrins -- Chemical properties, Porphyrins -- Optical properties, Chemicals, plastics and rubber industries
Abstract

The photophysics of protonated protoporphyrin and three tetraaryporphyrin cations upon 390 nm irradiation is examined. Dissociation lifetimes of photoexcited porphyrin cations are measured in an electrostatic ion storage ring.

Published
2005

24. Investigation of the thermoelectric response in conducting polymers doped by solid-state diffusion

Author

Kang, Keehoon, Schott, Sam, Venkateshvaran, Deepak, Broch, Katharina, Schweicher, Guillaume, Harkin, David, Jellett, Cameron, Nielsen, Christian B., McCulloch, Iain, Sirringhaus, Henning, Kang, Keehoon, Schott, Sam, Venkateshvaran, Deepak, Broch, Katharina, Schweicher, Guillaume, Harkin, David, Jellett, Cameron, Nielsen, Christian B., McCulloch, Iain, and Sirringhaus, Henning

Abstract

Thermoelectric effect is a physical phenomenon which intricately relates the thermal energy of charge carriers to their charge transport. Understanding the mechanism of this interaction in different systems lies at the heart of inventing novel materials which can revolutionize thermoelectric power generation technology. Despite the recent surge of interest in organic thermoelectric materials, the community has had difficulties in formulating the charge transport mechanism in the presence of a significant degree of disorder. Here, we analyze the thermoelectric properties of various conducting polymers doped by solid-state diffusion of dopant molecules based on a transport model with a power law energy dependence of transport function. A fine control of the degree of doping via postdoping annealing provides an accurate empirical evidence of a strong energy dependence of the carrier mobility in the conducting polymers. A superior thermoelectric power factor of conducting polymers doped by solid-state diffusion to that of other doping methods can be attributed to a resulting higher intrinsic mobility and higher free carrier concentration., info:eu-repo/semantics/published

Published
2019

25. Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors

Author

Nielsen, Christian B, Giovannitti, Alexander, Sbircea, Dan-Tiberiu, Bandiello, Enrico, Niazi, Muhammad R, Hanifi, David A, Sessolo, Michele, Amassian, Aram, Malliaras, George G, Rivnay, Jonathan, McCulloch, Iain, Commission of the European Communities, Malliaras, George [0000-0002-4582-8501], and Apollo - University of Cambridge Repository

Subjects
0306 Physical Chemistry (incl. Structural), General Chemistry, 0303 Macromolecular and Materials Chemistry, 03 Chemical Sciences, 0912 Materials Engineering
Abstract

The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous environment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, electrochromic properties, operational voltage, and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT-based devices, and show stability under aqueous operation without the need for formulation additives and cross-linkers.

Published
2018
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27. 2,1,3-Benzothiadiazole-5,6-Dicarboxylic Imide – A Versatile Building Block for Additive- and Annealing-Free Processing of Organic Solar Cells with Efficiencies Exceeding 8%

Author

Nielsen, Christian B, Ashraf, Raja Shahid, Treat, Neil D, Schroeder, Bob C, Donaghey, Jenny E, White, Andrew J P, Stingelin, Natalie, and McCulloch, Iain

Subjects
organic electronics, organic photovoltaics, Communications, donor–acceptor polymers
Abstract

A new photoactive polymer comprising benzo[1,2-b:3,4-b':5,6-d']trithiophene and 2,1,3-benzothiadiazole-5,6-dicarboxylic imide is reported. The synthetic design allows for alkyl chains to be introduced on both electron-rich and electron-deficient components, which in turn allows for rapid optimization of the alkyl chain substitution pattern. Consequently, the optimized polymer shows a maximum efficiency of 8.3% in organic photovoltaic devices processed in a commercially viable fashion without solvent additives, annealing, or device engineering.

Published
2014

28. Performance Improvements in Conjugated Polymer Devices by Removal of Water-Induced Traps

Author

Nikolka, Mark, Schweicher, Guillaume, Armitage, John, Nasrallah, Iyad, Jellett, Cameron, Guo, Zhijie, Hurhangee, Michael, Sadhanala, Aditya, McCulloch, Iain, Nielsen, Christian B., Sirringhaus, Henning, Nikolka, Mark, Schweicher, Guillaume, Armitage, John, Nasrallah, Iyad, Jellett, Cameron, Guo, Zhijie, Hurhangee, Michael, Sadhanala, Aditya, McCulloch, Iain, Nielsen, Christian B., and Sirringhaus, Henning

Abstract

The exploration of a wide range of molecular structures has led to the development of high‐performance conjugated polymer semiconductors for flexible electronic applications including displays, sensors, and logic circuits. Nevertheless, many conjugated polymer field‐effect transistors (OFETs) exhibit nonideal device characteristics and device instabilities rendering them unfit for industrial applications. These often do not originate in the material's intrinsic molecular structure, but rather in external trap states caused by chemical impurities or environmental species such as water. Here, a highly efficient mechanism is demonstrated for the removal of water‐induced traps that are omnipresent in conjugated polymer devices even when processed in inert environments; the underlying mechanism is shown, by which small‐molecular additives with water‐binding nitrile groups or alternatively water–solvent azeotropes are capable of removing water‐induced traps leading to a significant improvement in OFET performance. It is also shown how certain polymer structures containing strong hydrogen accepting groups will suffer from poor performances due to their high susceptibility to interact with water molecules; this allows the design guidelines for a next generation of stable, high‐performing conjugated polymers to be set forth., info:eu-repo/semantics/published

Published
2018

29. N-type organic electrochemical transistors with stability in water

Author

Giovannitti, Alexander, Nielsen, Christian B, Sbircea, Dan-Tiberiu, Inal, Sahika, Donahue, Mary, Niazi, Muhammad R, Hanifi, David A, Amassian, Aram, Malliaras, George G, Rivnay, Jonathan, McCulloch, Iain, Malliaras, George [0000-0002-4582-8501], Apollo - University of Cambridge Repository, Commission of the European Communities, and Engineering & Physical Science Research Council (EPSRC)

Subjects
0306 Physical Chemistry (incl. Structural), HIGH-MOBILITY, Science & Technology, DEVICES, Science, BUILDING-BLOCK, POLYMER, 0303 Macromolecular and Materials Chemistry, SEMICONDUCTORS, TRANSPORT, Multidisciplinary Sciences, TRANSCONDUCTANCE, Science & Technology - Other Topics, THIN-FILM TRANSISTORS, 0912 Materials Engineering
Abstract

Organic electrochemical transistors (OECTs) are receiving significant attention due to their ability to efficiently transduce biological signals. A major limitation of this technology is that only p-type materials have been reported, which precludes the development of complementary circuits, and limits sensor technologies. Here, we report the first ever n-type OECT, with relatively balanced ambipolar charge transport characteristics based on a polymer that supports both hole and electron transport along its backbone when doped through an aqueous electrolyte and in the presence of oxygen. This new semiconducting polymer is designed specifically to facilitate ion transport and promote electrochemical doping. Stability measurements in water show no degradation when tested for 2 h under continuous cycling. This demonstration opens the possibility to develop complementary circuits based on OECTs and to improve the sophistication of bioelectronic devices.

Published
2016

30. The Dalton quantum chemistry program system

Author

Aidas, Kestutis, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linus, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pal, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa., Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thomas, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andreas, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Anders, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvinas, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., Sanchez de Merás, Alfredo, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Aidas, Kestuti, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linu, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pål, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thoma, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa, Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thoma, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andrea, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Ander, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvina, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., de Merás, Alfredo Sánchez, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Dipartimento di Chimica, Università degli Studi di Ferrara (UniFE), Centre for Theoretical and Computational Chemistry [Oslo] (CTCC), Department of Chemistry [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Department of Physics, Chemistry and Biology, Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratory of the Department of Oncology (DEPARTMENT OF ONCOLOGY), Herlev and Gentofte Hospital, Norwegian Meteorological Institute [Oslo] (MET), Teoretisk Kemi, Aarhus University [Aarhus], Centre for Biodiversity Dynamics, Norwegian University of Science and Technology [Trondheim] (NTNU), Norwegian University of Science and Technology (NTNU)-Norwegian University of Science and Technology (NTNU), Karlsruhe Institute of Technology (KIT), Department of Theoretical Chemistry, University Düsseldorf, Department of Mathematics, Tokyo University of Science, Institut Jean-Pierre Bourgin (IJPB), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Department of Environmental Engineering, Technical University of Denmark [Lyngby] (DTU), Computer Services Networks and Systems, Università degli Studi di Modena e Reggio Emilia (UNIMORE), Hammersmith Hospital, Imperial College, London, Department of Haematology, Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Centre for Theoretical and Computational Chemistry, University of Tromsø (UiT), Department of Electronics Materials and Devices, Ivanovo State University of Chemistry and Technology, Department of Chemistry [Copenhagen], Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California [San Diego] (UC San Diego), University of California-University of California, School of Chemistry, University of Nottingham, UK (UON), Theoretical Chemistry, Royal Institute of Technology [Stockholm] (KTH ), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Norwegian Meteorological Institute, Bakke, Vebjørn, Hjertenaes, Eirik, Høyvik, Ida Marie, Jensen, Hans Jørgen A. a., Kjaergaard, Thoma, Lutnaes, Ola B., Sánchez de Merás, Alfredo, Sylvester Hvid, Kristian O., Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Materials Chemistry2506 Metals and Alloys, Software Focus, Ab initio electronic structure methods structure methods, ab initio calculations, VDP::Mathematics and natural science: 400::Chemistry: 440::Theoretical chemistry, quantum chemistry: 444, Computer Science Applications1707 Computer Vision and Pattern Recognition, Quantum chemistry program, Ab-initio methods, Scientific Software, Quantum Chemistry, Molecular properties, Biochemistry, Algorithms, [Electronic Structure Theory], Algorithm, Molecular propertie, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Computational Chemistry, Computational Mathematic, Faculty of Science, Physical and Theoretical Chemistry, VDP::Matematikk og Naturvitenskap: 400::Kjemi: 440::Teoretisk kjemi, kvantekjemi: 444
Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self-consistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms. © 2013 John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, (CC BY-NC-ND 3.0)

Published
2014

31. Molecular tuning of phenylene-vinylene derivatives for two-photon photosensitized singlet oxygen production

Author

Nielsen, Christian B., Arnbjerg, Jacob, Johnsen, Mette, Jorgensen, Mikkel, and Ogilby, Peter R.

Subjects
Ketones -- Chemical properties, Ketones -- Structure, Carbonyl compounds -- Chemical properties, Carbonyl compounds -- Structure, Chromophores -- Chemical properties, Chromophores -- Structure, Absorption spectra -- Analysis, Biological sciences, Chemistry
Abstract

Several analyses are conducted to explain the various effects of the molecular changes taking place in the sensitizer on the molecular tuning of the phenylene-vinylene derivatives. The presence of a ketone moiety in the sensitizer is shown to be extremely useful in an efficient production of singlet oxygen.

Published
2009

32. Effect of sensitizer protonation on singlet oxygen production in aqueous and nonaqueous media

Author

Arnbjerg, Jacob, Johnsen, Mette, Nielsen, Christian B., Jorgensen, Mikkel, and Ogilby, Peter R.

Subjects
Oxygen -- Chemical properties, Oxygen -- Optical properties, Photosensitizing compounds -- Usage, Amines -- Chemical properties, Amines -- Optical properties, Chemicals, plastics and rubber industries
Abstract

The protonation of photosensitizers whose chromophores contain amine functional groups has adversely affected the singlet oxygen yield in aqueous and non-aqueous media. The analysis is helpful in understanding and controlling the behavior of photosensitizers in systems with microheterogeneous domains that have appreciable pH gradients.

Published
2007

33. Two-photon photosensitized production of singlet oxygen: Sensitizers with phenylene-ethynylene-based chromophores

Author

McIlroy, Sean P., Clo, Emiliano, Nikolajsen, Lars, Frederiksen, Peter K., Nielsen, Christian B., Mikkelsen, Kurt V., Gothelf, Kurt V., and Ogilby, Peter R.

Subjects
Photosensitizing compounds -- Chemical properties, Chromophores -- Chemical properties, Chromophores -- Research, Biological sciences, Chemistry
Abstract

Singlet molecular oxygen [A(super 1) delta(sub g)] is produced and optically monitored in time-resolved experiments upon nonlinear two-photon excitation of photosensitizers that contain triple bonds as an integral part of the chromophore. Most importantly, however, in comparison to the analogue that contains double bonds, the sensitizer containing alkyne moieties is more stable against singlet-oxygen mediated photooxygenation reactions.

Published
2005

35. N-type organic electrochemical transistors with stability in water

Author

Giovannitti, Alexander, primary, Nielsen, Christian B., additional, Sbircea, Dan-Tiberiu, additional, Inal, Sahika, additional, Donahue, Mary, additional, Niazi, Muhammad R., additional, Hanifi, David A., additional, Amassian, Aram, additional, Malliaras, George G., additional, Rivnay, Jonathan, additional, and McCulloch, Iain, additional

Published
2016
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36. High-efficiency and air-stable P3HT-based polymer solar cells with a new non-fullerene acceptor

Author

Holliday, Sarah, primary, Ashraf, Raja Shahid, additional, Wadsworth, Andrew, additional, Baran, Derya, additional, Yousaf, Syeda Amber, additional, Nielsen, Christian B., additional, Tan, Ching-Hong, additional, Dimitrov, Stoichko D., additional, Shang, Zhengrong, additional, Gasparini, Nicola, additional, Alamoudi, Maha, additional, Laquai, Frédéric, additional, Brabec, Christoph J., additional, Salleo, Alberto, additional, Durrant, James R., additional, and McCulloch, Iain, additional

Published
2016
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37. The Dalton quantum chemistry program system

Author

Aidas, Kestutis, Angeli, Celestino, Bak, Keld L., Bast, Radovan, Boman, Linus, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dalskov, Erik K., Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenaes, Eirik, Iozzi, Maria Francesca, Jonsson, Dan, Kauczor, Joanna, Kirpekar, Sheela, Kjaergaard, Thomas, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andreas, Kristensen, Kasper, Ligabue, Andrea, Lutnaes, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Osted, Anders, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvinas, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sa?ek, Pawel, Samson, Claire C. M., Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Vahtras, Olav, Watson, Mark A., Wilson, David J. D., and Ziolkowski, Marcin

Published
2013

39. Nucleus-independent chemical shift criterion for aromaticity in pi-extended tetraoxa[8]circulenes

Author

Baryshnikov, Gleb V., Minaev, Boris F., Pittelkow, Michael, Nielsen, Christian B., Salcedo, Roberto, Baryshnikov, Gleb V., Minaev, Boris F., Pittelkow, Michael, Nielsen, Christian B., and Salcedo, Roberto

Abstract

Recently synthesized pi-extended symmetrical tetraoxa[8]circulenes that exhibit electroluminescent properties were calculated at the density functional theory (DFT) level using the quantum theory of atoms in molecules (QTAIM) approach to electron density distribution analysis. Nucleus-independent chemical shift (NICS) indices were used to characterize the aromaticity of the studied molecules. The tetraoxa[8]circulene molecules were found to consist of two antiaromatic perimeters (according to the Huckel "4n" antiaromaticity rule) that include 8 and 24 pi-electrons. Conversely, NICS calculations demonstrated the existence of a common pi-extended system (distributed like a flat ribbon) in the studied tetraoxa[8]circulene molecules. Thus, these symmetrical tetraoxa[8]circulene molecules provide examples of diatropic systems characterized by the presence of induced diatropic ring currents., QC 20130222

Published
2013
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40. Influence of Crystallinity and Energetics on Charge Separation in Polymer–Inorganic Nanocomposite Films for Solar Cells

Author

Bansal, Neha, primary, Reynolds, Luke X., additional, MacLachlan, Andrew, additional, Lutz, Thierry, additional, Ashraf, Raja Shahid, additional, Zhang, Weimin, additional, Nielsen, Christian B., additional, McCulloch, Iain, additional, Rebois, Dylan G., additional, Kirchartz, Thomas, additional, Hill, Michael S., additional, Molloy, Kieran C., additional, Nelson, Jenny, additional, and Haque, Saif A., additional

Published
2013
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42. Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells.

Author

Dimitrov, Stoichko D., Schroeder, Bob C., Nielsen, Christian B., Bronstein, Hugo, Zhuping Fei, McCulloch, Iain, Heeney, Martin, and Durrant, James R.

Subjects
CONJUGATED polymers synthesis, EXCITON theory, SOLAR cells, PHOTOCURRENTS, BAND gaps
Abstract

The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law. [ABSTRACT FROM AUTHOR]

Published
2016
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44. Two-photon photosensitized production of singlet oxygen in water

Author

Frederiksen, Peter K., McIlroy, Sean P., Nielsen, Christian B., Nikolajsen, Lars, Skovsen, E., Jørgensen, Mikkel, Mikkelsen, K.V., Ogilby, P.R., Frederiksen, Peter K., McIlroy, Sean P., Nielsen, Christian B., Nikolajsen, Lars, Skovsen, E., Jørgensen, Mikkel, Mikkelsen, K.V., and Ogilby, P.R.

Published
2005

46. Molecular recognition: Comparative study of a tunable host-guest system by using a fluorescent model system and collision-induced dissociation mass spectrometry on dendrimers

Author

Pittelkow, Michael, Nielsen, Christian B., Broeren, M. A., van Dongen, J. L. J., van Genderen, M. H. P., Meijer, E. W., Christensen, Jørn Bolstad, Pittelkow, Michael, Nielsen, Christian B., Broeren, M. A., van Dongen, J. L. J., van Genderen, M. H. P., Meijer, E. W., and Christensen, Jørn Bolstad

Published
2005

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