Article
Chemistry, Multidisciplinary
Kevin S. Mayer, Daniel J. Adams, Naresh Eedugurala, Molly M. Lockart, Paramasivam Mahalingavelar, Lifeng Huang, Luke A. Galuska, Eric R. King, Xiaodan Gu, Michael K. Bowman, Jason D. Azoulay
Summary: The study demonstrates a new class of strongly p-conjugated copolymers, where atom-specific substitution modulates local aromatic character, resulting in dramatic differences in structural, electronic, and magnetic properties of the polymers. These long-range p-mediated interactions facilitate control between low-spin aromatic and high-spin quinoidal forms.
CELL REPORTS PHYSICAL SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Chen Lu, Eunkyung Cho, Zhiyuan Cui, Yuhang Gao, Wenjuan Cao, Jean-Luc Bredas, Veaceslav Coropceanu, Feng Li
Summary: In contrast to closed-shell luminescent molecules, organic luminescent radicals have both spin doublet electronic states, resulting in spin-allowed radiative transitions. The efficiency and stability of donor-acceptor (D-A center dot) type luminescent radicals, which have a donor group covalently attached to an electron-withdrawing radical core, remain challenging to define. Experimental and theoretical results suggest that the luminescence efficiency and stability of the radicals are determined by the degree of conjugation and the number of imine nitrogen atoms in the substituents, with higher conjugation and lower number of imine nitrogen atoms leading to higher efficiency and stability.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Yiwen Ji, Xinyu Mu, Hang Yin, Bin Cui, Xiaotao Hao, Kun Gao
Summary: Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) have achieved rapid development, but the role of donor/acceptor (D/A) interfaces in NFA-based heterosystems has not been fully addressed. In this study, we found that the photoinduced spontaneous charge separation efficiency in typical NFA heterosystems can reach up to 67%, while the contribution of the D/A interface to charge separation efficiency is only 25%. The D/A interface plays a more important role in reducing the charge recombination rate and optimizing the competition between radiative and nonradiative charge recombination to minimize the nonradiative voltage loss.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Joshua J. Sutton, Dan Preston, Philipp Traber, Johannes Steinmetzer, Xue Wu, Surajit Kayal, Xue-Z Sun, James D. Crowley, Michael W. George, Stephan Kupfer, Keith C. Gordon
Summary: The optical properties of two Re(CO)(3)(bpy)Cl complexes with different substituents were studied, revealing distinct charge transfer bands in their absorption spectra and two emissive states in their excited-state spectroscopy which are modulated by solvent. Time-resolved infrared spectroscopy identified the nature of the excited states in different solvents, with DFT calculations suggesting that the switching of properties induced by solvent is controlled by spin-orbit coupling.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Naresh Eedugurala, Michael E. Steelman, Paramasivam Mahalingavelar, Daniel J. Adams, Kevin S. Mayer, Chih-Ting Liu, Anthony Benasco, Guorong Ma, Xiaodan Gu, Michael K. Bowman, Jason D. Azoulay
Summary: Open-shell conjugated polymers offer new opportunities to integrate the spin degree of freedom within emerging technologies. This study demonstrates a high-spin conjugated polymer composed of alternating benzo[1,2-b:4,5-b']dithiophene donors and a new, strongly electron-withdrawing 6,7,8,9-tetrachloro-[1,2,5]thiadiazolo[3,4-b]phenazine acceptor. The use of annulation and chlorination facilitates a transition between closed-shell aromatic and high-spin quinoidal forms, resulting in reduced bandgap, high electron affinity, delocalization of spin density, and n-type conduction. These insights allow for the development of a broader range of open-shell conjugated polymers and enable manipulation of important properties.
CHEMISTRY OF MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Sheik Haseena, Mahesh Kumar Ravva
Summary: Van der Waals forces are responsible for the stability of conjugated polymer-acceptor complexes, with electron transfer typically occurring via photoinduced electron transfer from donor materials to acceptor materials. Density functional theory-based methods were used to study partial ground-state charge transfer in the all-polymer donor-acceptor interface.
JOURNAL OF ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Organic
Kazumasa Funabiki, Kengo Yamada, Yuta Arisawa, Arina Watanabe, Tomohiro Agou, Yasuhiro Kubota, Toshiyasu Inuzuka, Yohei Miwa, Taro Udagawa, Shoichi Kutsumizu
Summary: A series of perfluoronaphthalene-based donor-acceptor-donor fluorescent dyes were successfully synthesized using a one-step route. The perfluoronaphthalene moiety served as a good electron-accepting aromatic ring with excellent intramolecular charge transfer properties. Replacing the naphthalene ring with perfluoronaphthalene stabilized the energy levels and reduced the energy band gap, leading to a change in the emission color. Among the synthesized dyes, those with diphenylamino groups showed the highest fluorescence quantum yields in solution and film, while the dye with carbazoyl group exhibited the highest fluorescence quantum yield in the crystalline state.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Taeyeon Kim, Yuanning Feng, James P. O'Connor, J. Fraser Stoddart, Ryan M. Young, Michael R. Wasielewski
Summary: Designing and controlling charge transfer pathways in organic semiconductors are crucial for solar energy applications. This study investigates the photoinduced charge transfer and relaxation dynamics in host-guest complexes, and demonstrates that the charge transfer pathway can be controlled by subtle chemical modifications of the acceptor host.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Alexander Aster, Christopher Rumble, Anna-Bea Bornhof, Hsin-Hua Huang, Naomi Sakai, Tomas Solomek, Stefan Matile, Eric Vauthey
Summary: The study focuses on the charge-transfer dynamics of electron donor-acceptor dyads based on NDI chromophores, demonstrating long-lived charge separation in the triplet state can be achieved by controlling the mutual orientation of the donor-acceptor sub-units.
Article
Chemistry, Physical
Hak-Won Nho, Won-Woo Park, Byongkyu Lee, Seoyoung Kim, Changduk Yang, Oh-Hoon Kwon
Summary: By studying the photophysics of the high-performance donor-acceptor polymer PM6 in single chains, the formation of CT states and their equilibrium with parent LE states can be revealed, which is essential for optimizing organic photovoltaic devices.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Shuya Zhao, Zhiqiang Zheng, Lu Qi, Yurui Xue, Yuliang Li
Summary: This study discovered a novel catalyst structure with efficient charge transfer at the interface, enabling high catalytic activity and stability. The catalyst demonstrated high efficiency for ammonia production through nitrate reduction reaction, with excellent yields and stability. This finding has significant implications for catalytic research and potential applications.
Article
Chemistry, Multidisciplinary
Midori Kawashiro, Tatsuya Mori, Masato Ito, Naoki Ando, Shigehiro Yamaguchi
Summary: A new class of donor-pi-acceptor fluorophores with ortho-P(=X)R-2-substituted phenyl groups (X=O or S) as a photodissociation module is reported. The P=X moiety coordinates to the boron atom and undergoes dissociation in the excited state, resulting in dual emission from tetra- and tricoordinate boron species. The intensity ratios of the dual emission bands are sensitive to environmental parameters and single-molecule white emission can be achieved by precise tuning of the P(=X)R-2 group and the electron-donating amino moiety in solution.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Amani Benhnia, Shinta Watanabe, Rouzhaji Tuerhong, Masato Nakaya, Jun Onoe, Jean-Pierre Bucher
Summary: This study aims to investigate changes in the properties of organic optoelectronic layers close to metal contacts. By using experimental and computational methods, it was found that C-60 and ZnPc interact to form a complex on a silver substrate, with significant charge transfer between the components.
Article
Polymer Science
Hailong Wang, Nianqiang Jiang, Qinglei Zhang, Guojing Xie, Ningning Tang, Linlin Liu, Zengqi Xie
Summary: Conjugation breaking by node structures in D-n-A-type molecules allows for facile tuning of oxidation and reduction behaviors. Electrochemical polymerization on electrodes produces a series of cross-linked polymers with versatile redox properties. One polymer, poly-2T(3)-PDI, shows balanced ambipolar characteristics and potential for application in pseudocapacitors.
Article
Physics, Condensed Matter
Teng Zhang, Tingting Wang, Cesare Grazioli, Ambra Guarnaccio, Iulia Emilia Brumboiu, Fredrik O. L. Johansson, Klara Beranova, Marcello Coreno, Monica de Simone, Barbara Brena, Liwei Liu, Yeliang Wang, Carla Puglia
Summary: This study performed a spectroscopic investigation on the vertical heterostructure of m-MTDATA (donor) and PPT (acceptor) molecules. The electronic properties of the donor/acceptor interface were thoroughly characterized, revealing the presence of novel hybridized states resulting from the interaction between the donor and acceptor molecules at the interface. These hybridized states have a significant impact on charge transport in organic electronic devices, which may explain the increased device efficiency when using donor-acceptor molecules.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Chemistry, Multidisciplinary
Zhen Zhang, Shiv Kumar, Sergey Bagnich, Eduard Spuling, Fabian Hundemer, Martin Nieger, Zahid Hassan, Anna Koehler, Eli Zysman-Colman, Stefan Braese
FRONTIERS IN CHEMISTRY
(2020)
Article
Chemistry, Multidisciplinary
Heinz Baessler, Daniel Kroh, Franz Schauer, Vojtech Nadazdy, Anna Koehler
Summary: The study employs ER-EIS technique to investigate the DOS distributions of HOMO and LUMO states in organic semiconductors, revealing Gaussian-shaped cores with low energy tails in neat and blended films. Comparison between ER-EIS and PE/IPE spectra of P3HT suggests an overestimation of distribution width by a factor of 2-3 in the latter. Additionally, DOS width is found to increase in blends of MeLPPP and SF-PDI2 or PC(61)BM compared to neat films.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Physical
Steponas Raisys, Ona Adomeniene, Povilas Adomenas, Alexander Rudnick, Anna Koehler, Karolis Kazlauskas
Summary: In this study, the diffusion and quenching of triplet excitons in solid state upconversion films based on two different BFA emitters and PtOEP sensitizer were investigated. It was found that the BFA-Ph film exhibited faster triplet exciton quenching rate, leading to optimal UC performance at lower temperatures than the BFA-Me film.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Hannah Kurz, Konstantin Schoetz, Ilias Papadopoulos, Frank W. Heinemann, Harald Maid, Dirk M. Guldi, Anna Koehler, Gerald Hoerner, Birgit Weber
Summary: The study presents a family of planar nickel(II) complexes with sensitive CISSS tracked by fluorescence detection. These complexes fluoresce in noncoordinating solvents but are fluorescence-silent in the presence of axial ligands. FD-CISSS shows higher sensitivity compared to absorption-based CISSS.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Moritz Brutting, Johannes M. Foerster, Stephan Kummel
Summary: In this study, the primary charge separation step in the homodimeric reaction center of Heliobacterium modesticaldum was calculated from first principles. The results showed a certain spectral overlap between the forward-charge transfer and the coupled Q(x) excitations, indicating a complex mechanism for charge transfer in the system. The influence of thermal vibrations on the excited states were also revealed through ab initio Born-Oppenheimer molecular dynamics simulations, demonstrating the reliability and robustness of the findings.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Materials Science, Multidisciplinary
Tobias Meier, Heinz Baessler, Anna Koehler
Summary: The authors utilized kinetic Monte Carlo studies to investigate the impact of grain boundaries on the performance of OFET, finding that parameters controlling the position of the Fermi level affect charge transport. Guidelines for optimizing film morphology for different transport modes were derived from the research.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Optics
Sebastian Hammon, Linn Leppert, Stephan Kuemmel
Summary: In the presence of acetophenone, the magnetic moments of small palladium clusters are reduced, indicating a direct consequence of electronic interaction between the Pd clusters and solvent molecules. This reduction in magnetic moment is not due to a different cluster geometry being stabilized by the solvation shell.
EUROPEAN PHYSICAL JOURNAL D
(2021)
Article
Chemistry, Physical
Sebastian Hammon, Mara Klarner, Gerald Horner, Birgit Weber, Martin Friedrich, Jurgen Senker, Rhett Kempe, Thiago Branquinho de Queiroz, Stephan Kummel
Summary: Loading with nickel significantly increases the photocatalytic hydrogen evolution rates in a system combining a photosensitizer and metal cluster. Theoretical calculations show that the charge transfer from metal to photosensitizer plays a crucial role in the optical excitations of the system. Additionally, the binding energy between nickel and the photosensitizer is considerably higher than that of palladium and platinum.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Moritz Bruetting, Hilke Bahmann, Stephan Kuemmel
Summary: This work explores the self-consistent implementation of a local range-separated hybrid and discusses different forms of the local range-separation function. Experimental results demonstrate that this approach is significantly better than common global range-separated hybrid functionals in terms of atomization energy, reaction barrier height, and total energy of atoms. Furthermore, promising results are obtained for equilibrium bond lengths, harmonic vibrational frequencies, and vertical ionization potentials, highlighting the potential and flexibility of this approach.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
T. Trepl, I Schelter, S. Kuemmel
Summary: This article introduces the use of real-time DFT for analyzing excitation-energy transfer and discusses several measures of energy transfer based on time-dependent density. These measures are well-founded in the DFT framework, allow for intuitive understanding and visualization, and reproduce important limiting cases of an analytical model.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Sabrina Volpert, Zohreh Hashemi, Johannes M. Foerster, Mario R. G. Marques, Ingo Schelter, Stephan Kuemmel, Linn Leppert
Summary: In this study, the electronic and excited-state structure of the primary pigments in the reaction center of Rhodobacter sphaeroides were investigated using first principles time-dependent density functional theory. By considering the protein environment, the effect of the surrounding amino-acid residues on energy and charge-transfer excitations was systematically studied. The results suggest a mechanism for charge-transfer in this bacterial reaction center and provide a foundation for further investigations of the interplay between delocalized excited states, vibronic coupling, and the role of the protein environment in complex light-harvesting systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Moritz Bruetting, Johannes M. Foerster, Stephan Kuemmel
Summary: This study reveals the key steps in the process of solar energy production through theoretical calculations and experimental analysis. The results show that the protein environment plays an important role in electron transfer and charge separation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Physics, Multidisciplinary
Timo Lebeda, Thilo Aschebrock, Stephan Kuemmel
Summary: It has been shown that using the meta-GGA form in density functional theory can accurately predict band gaps in solids and maintain reasonable accuracy in electronic binding energies.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Optics
Sebastian Hammon, Stephan Kuemmel
Summary: We simulate photoemission from an electronically excited system by computing electron density escape in real space in real time. For a one-electron system, angular resolved photoemission can be interpreted as the mapping of a previously unoccupied orbital. In the molecule perylene-3,4,9,10-tetracarboxylic dianhydride, angular resolved photoemission reveals signatures of the many-particle character of the first electronic excitation.
Article
Materials Science, Multidisciplinary
R. Saxena, V. R. Nikitenko, I. I. Fishchuk, Ya Burdakov, Yu Metel, J. Genoe, H. Baessler, A. Koehler, A. Kadashchuk
Summary: The study found that the C factor for Marcus polaron hopping depends on the degree of carrier localization, whether quasi-equilibrium has been reached, and the sigma/E-a ratio. This implies that there is no universal scaling with respect to the relative contribution of polaron and disorder effect.