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Jahangir TN, Abdel-Azeim S, Kandiel TA. BiVO 4 Photoanode with NiV 2O 6 Back Contact Interfacial Layer for Improved Hole-Diffusion Length and Photoelectrochemical Water Oxidation Activity. ACS APPLIED MATERIALS & INTERFACES 2024; 16:28742-28755. [PMID: 38801716 DOI: 10.1021/acsami.4c05489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The short hole diffusion length (HDL) and high interfacial recombination are among the main drawbacks of semiconductor-based solar energy systems. Surface passivation and introducing an interfacial layer are recognized for enhancing HDL and charge carrier separation. Herein, we introduced a facile recipe to design a pinholes-free BiVO4 photoanode with a NiV2O6 back contact interfacial (BCI) layer, marking a significant advancement in the HDL and photoelectrochemical activity. The fabricated BiVO4 photoanode with NiV2O6 BCI layer exhibits a 2-fold increase in the HDL compared to pristine BiVO4. Despite this improvement, we found that the front surface recombination still hinders the water oxidation process, as revealed by photoelectrochemical (PEC) studies employing Na2SO3 electron donors and by intensity-modulated photocurrent spectroscopy measurements. To address this limitation, the surface of the NiV2O6/BiVO4 photoanode was passivated with a cobalt phosphate electrocatalyst, resulting in a dramatic enhancement in the PEC performance. The optimized photoanode achieved a stable photocurrent density of 4.8 mA cm-2 at 1.23 VRHE, which is 12-fold higher than that of the pristine BiVO4 photoanode. Density Functional Theory (DFT) simulations revealed an abrupt electrostatic potential transition at the NiV2O6/BiVO4 interface with BiVO4 being more negative than NiV2O6. A strong built-in electric field is thus generated at the interface and drifts photogenerated electrons toward the NiV2O6 BCI layer and photogenerated holes toward the BiVO4 top layer. As a result, the back-surface recombination is minimized, and ultimately, the HDL is extended in agreement with the experimental findings.
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Affiliation(s)
- Tahir Naveed Jahangir
- Department of Chemistry, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia
| | - Safwat Abdel-Azeim
- Center for Integrative Petroleum Research (CIPR), College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Tarek A Kandiel
- Department of Chemistry, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia
- Interdisciplinary Research Center for Hydrogen and Energy Storage (IRC-HES), KFUPM, Dhahran 31261, Saudi Arabia
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2
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Carr JM, Allen TG, Larson BW, Davydenko IG, Dasari RR, Barlow S, Marder SR, Reid OG, Rumbles G. Short and long-range electron transfer compete to determine free-charge yield in organic semiconductors. MATERIALS HORIZONS 2022; 9:312-324. [PMID: 34787147 DOI: 10.1039/d1mh01331a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding how Frenkel excitons efficiently split to form free-charges in low-dielectric constant organic semiconductors has proven challenging, with many different models proposed in recent years to explain this phenomenon. Here, we present evidence that a simple model invoking a modest amount of charge delocalization, a sum over the available microstates, and the Marcus rate constant for electron transfer can explain many seemingly contradictory phenomena reported in the literature. We use an electron-accepting fullerene host matrix dilutely sensitized with a series of electron donor molecules to test this hypothesis. The donor series enables us to tune the driving force for photoinduced electron transfer over a range of 0.7 eV, mapping out normal, optimal, and inverted regimes for free-charge generation efficiency, as measured by time-resolved microwave conductivity. However, the photoluminescence of the donor is rapidly quenched as the driving force increases, with no evidence for inverted behavior, nor the linear relationship between photoluminescence quenching and charge-generation efficiency one would expect in the absence of additional competing loss pathways. This behavior is self-consistently explained by competitive formation of bound charge-transfer states and long-range or delocalized free-charge states, where both rate constants are described by the Marcus rate equation. Moreover, the model predicts a suppression of the inverted regime for high-concentration blends and efficient ultrafast free-charge generation, providing a mechanistic explanation for why Marcus-inverted-behavior is rarely observed in device studies.
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Affiliation(s)
- Joshua M Carr
- University of Colorado Boulder, Materials Science & Engineering Program, Boulder, CO, 80303, USA
| | - Taylor G Allen
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Bryon W Larson
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Iryna G Davydenko
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Raghunath R Dasari
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Stephen Barlow
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Seth R Marder
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemical and Biological Engineering, Boulder, CO, 80303, USA
| | - Obadiah G Reid
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Garry Rumbles
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
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3
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Kaiser C, Sandberg OJ, Zarrabi N, Li W, Meredith P, Armin A. A universal Urbach rule for disordered organic semiconductors. Nat Commun 2021; 12:3988. [PMID: 34183659 PMCID: PMC8238995 DOI: 10.1038/s41467-021-24202-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
In crystalline semiconductors, absorption onset sharpness is characterized by temperature-dependent Urbach energies. These energies quantify the static, structural disorder causing localized exponential-tail states, and dynamic disorder from electron-phonon scattering. Applicability of this exponential-tail model to disordered solids has been long debated. Nonetheless, exponential fittings are routinely applied to sub-gap absorption analysis of organic semiconductors. Herein, we elucidate the sub-gap spectral line-shapes of organic semiconductors and their blends by temperature-dependent quantum efficiency measurements. We find that sub-gap absorption due to singlet excitons is universally dominated by thermal broadening at low photon energies and the associated Urbach energy equals the thermal energy, regardless of static disorder. This is consistent with absorptions obtained from a convolution of Gaussian density of excitonic states weighted by Boltzmann-like thermally activated optical transitions. A simple model is presented that explains absorption line-shapes of disordered systems, and we also provide a strategy to determine the excitonic disorder energy. Our findings elaborate the meaning of the Urbach energy in molecular solids and relate the photo-physics to static disorder, crucial for optimizing organic solar cells for which we present a revisited radiative open-circuit voltage limit.
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Affiliation(s)
- Christina Kaiser
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
| | - Oskar J. Sandberg
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
| | - Nasim Zarrabi
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
| | - Wei Li
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
| | - Paul Meredith
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
| | - Ardalan Armin
- grid.4827.90000 0001 0658 8800Sustainable Advanced Materials (Sêr-SAM), Department of Physics, Swansea University, Singleton Park, Swansea, UK
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4
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Taffet EJ, Lee BG, Toa ZSD, Pace N, Rumbles G, Southall J, Cogdell RJ, Scholes GD. Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States. J Phys Chem B 2019; 123:8628-8643. [PMID: 31553605 DOI: 10.1021/acs.jpcb.9b04027] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report quantum chemical calculations using multireference perturbation theory (MRPT) with the density matrix renormalization group (DMRG) plus photothermal deflection spectroscopy measurements to investigate the manifold of carotenoid excited states and establish their energies relative to the bright state (S2) as a function of nuclear reorganization. We conclude that the primary photophysics and function of carotenoids are determined by interplay of only the bright (S2) and lowest-energy dark (S1) states. The lowest-lying dark state, far from being energetically distinguishable from the lowest-lying bright state along the entire excited-state nuclear reorganization pathway, is instead computed to be either the second or first excited state depending on what equilibrium geometry is considered. This result suggests that, rather than there being a dark intermediate excited state bridging a non-negligible energy gap from the lowest-lying dark state to the lowest-lying bright state, there is in fact no appreciable energy gap to bridge following photoexcitation. Instead, excited-state nuclear reorganization constitutes the bridge from S2 to S1, in the sense that these two states attain energetic degeneracy along this pathway.
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Affiliation(s)
- Elliot J Taffet
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Benjamin G Lee
- Chemical and Materials Science Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Zi S D Toa
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Natalie Pace
- Chemical and Materials Science Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - Garry Rumbles
- Chemical and Materials Science Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
| | - June Southall
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences , University of Glasgow , University Avenue, Glasgow G12 8QQ , U.K
| | - Richard J Cogdell
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences , University of Glasgow , University Avenue, Glasgow G12 8QQ , U.K
| | - Gregory D Scholes
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
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5
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Hupfer ML, Herrmann‐Westendorf F, Kaufmann M, Weiß D, Beckert R, Dietzek B, Presselt M. Autonomous Supramolecular Interface Self‐Healing Monitored by Restoration of UV/Vis Absorption Spectra of Self‐Assembled Thiazole Layers. Chemistry 2019; 25:8630-8634. [DOI: 10.1002/chem.201901549] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Maximilian L. Hupfer
- Institute of Physical ChemistryFriedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
- Leibniz Institute of Photonic Technology (IPHT) Albert-Einstein-Str. 9 07745 Jena Germany
| | - Felix Herrmann‐Westendorf
- Institute of Physical ChemistryFriedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
- Leibniz Institute of Photonic Technology (IPHT) Albert-Einstein-Str. 9 07745 Jena Germany
| | - Martin Kaufmann
- Institute of Physical ChemistryFriedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
- Institute of Organic and Macromolecular ChemistryFriedrich Schiller University Jena Humboldstraße 10 07743 Jena Germany
| | - Dieter Weiß
- Institute of Organic and Macromolecular ChemistryFriedrich Schiller University Jena Humboldstraße 10 07743 Jena Germany
| | - Rainer Beckert
- Institute of Organic and Macromolecular ChemistryFriedrich Schiller University Jena Humboldstraße 10 07743 Jena Germany
| | - Benjamin Dietzek
- Institute of Physical ChemistryFriedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
- Leibniz Institute of Photonic Technology (IPHT) Albert-Einstein-Str. 9 07745 Jena Germany
| | - Martin Presselt
- Institute of Physical ChemistryFriedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
- Leibniz Institute of Photonic Technology (IPHT) Albert-Einstein-Str. 9 07745 Jena Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena)Friedrich Schiller University Jena Philosophenweg 7a 07743 Jena Germany
- sciclus GmbH & Co. KG Moritz-von-Rohr-Str. 1a 07745 Jena Germany
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6
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Zhang C, Heumueller T, Gruber W, Almora O, Du X, Ying L, Chen J, Unruh T, Cao Y, Li N, Brabec CJ. Comprehensive Investigation and Analysis of Bulk-Heterojunction Microstructure of High-Performance PCE11:PCBM Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2019; 11:18555-18563. [PMID: 31046222 DOI: 10.1021/acsami.8b22539] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Worldwide research efforts have been devoted to organic photovoltaics in the hope of a large-scale commercial application in the near future. To meet the industrial production requirements, organic photovoltaics that can reach power conversion efficiency (PCE) of over 10% along with promising operational device stability are of utmost interest. In the study, we take PCE11:PCBM as a model system, which can achieve over 11% PCE when processed from nonhalogen solvents, to deeply investigate the morphology-performance-stability correlation. We demonstrate that four batches of PCE11 with varying crystalline properties can achieve similar high performance in combination with PCBM. Careful device optimization is necessary in each case to properly address the requirements for the quite distinct microstructures. The bulk-heterojunction (BHJ) microstructure is comprehensively investigated as a function of the macromolecular weight and crystallinity. It is demonstrated that small differences in morphology significantly affect the kinetics and thermodynamic equilibrium of the BHJ microstructure as well as the photostability and thermal stability of the PCE11:PCBM solar cells.
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Affiliation(s)
- Chaohong Zhang
- SUSTech Academy for Advanced Interdisciplinary Studies , Southern University of Science and Technology , No. 1088, Xueyuan Road , 518055 Shenzhen , Guangdong , P. R. China
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
| | - Thomas Heumueller
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
| | - Wolfgang Gruber
- Institute for Crystallography and Structure Physics , Friedrich-Alexander University Erlangen-Nürnberg , Staudtstrasse 3 , 91058 Erlangen , Germany
| | - Osbel Almora
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
| | - Xiaoyan Du
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
| | - Lei Ying
- Institute of Polymer Optoelectronic Materials and Devices , South China University of Technology , 381 Wushan Road , 510640 Guangzhou , P. R. China
| | - Junwu Chen
- Institute of Polymer Optoelectronic Materials and Devices , South China University of Technology , 381 Wushan Road , 510640 Guangzhou , P. R. China
| | - Tobias Unruh
- Institute for Crystallography and Structure Physics , Friedrich-Alexander University Erlangen-Nürnberg , Staudtstrasse 3 , 91058 Erlangen , Germany
| | - Yong Cao
- Institute of Polymer Optoelectronic Materials and Devices , South China University of Technology , 381 Wushan Road , 510640 Guangzhou , P. R. China
| | - Ning Li
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
- National Engineering Research Center for Advanced Polymer Processing Technology , Zhengzhou University , No. 100 Science Avenue , 450002 Zhengzhou , P. R. China
| | - Christoph J Brabec
- Institute Materials for Electronics and Energy Technology (i-MEET) , Friedrich-Alexander University Erlangen-Nürnberg , Martensstrasse 7 , 91058 Erlangen , Germany
- Helmholtz-Institute Erlangen-Nürenberg (HIERN) , Immerwahrstr. 2 , 91058 Erlangen , Germany
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7
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Becker-Koch D, Rivkin B, Paulus F, Xiang H, Dong Y, Chen Z, Bakulin AA, Vaynzof Y. Probing charge transfer states at organic and hybrid internal interfaces by photothermal deflection spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:124001. [PMID: 30572317 DOI: 10.1088/1361-648x/aafa4e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In organic and hybrid photovoltaic devices, the asymmetry required for charge separation necessitates the use of a donor and an acceptor material, resulting in the formation of internal interfaces in the device active layer. While the core objective of these interfaces is to facilitate charge separation, bound states between electrons and holes may form across them, resulting in a loss mechanism that diminishes the performance of the solar cells. These interfacial transitions appear in organic systems as charge transfer (CT) states and as bound charge pairs (BCP) in hybrid systems. Despite being similar, the latter are far less investigated. Herein, we employ photothermal deflection spectroscopy and pump-push-probe experiments in order to determine the characteristics and dynamics of interfacial states in two model systems: an organic P3HT:PCBM and hybrid P3HT:ZnO photovoltaic layer. By controlling the area of the internal interface, we identify CT states between 1.4 eV and 1.8 eV in the organic bulk-heterojunction (BHJ) and BCP between 1.1 eV and 1.4 eV in the hybrid BHJ. The energetic distribution of these states suggests that they not only contribute to losses in photocurrent, but also significantly limit the possible maximum open circuit voltage obtainable from these devices.
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Affiliation(s)
- David Becker-Koch
- Kirchhoff Institut für Physik, Ruprecht-Karls-Universität, Heidelberg, Germany. Centre for Advanced Materials, Ruprecht-Karls-Universität, Heidelberg, Germany
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8
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Chen XK, Coropceanu V, Brédas JL. Assessing the nature of the charge-transfer electronic states in organic solar cells. Nat Commun 2018; 9:5295. [PMID: 30546009 PMCID: PMC6294259 DOI: 10.1038/s41467-018-07707-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 11/16/2018] [Indexed: 11/13/2022] Open
Abstract
The charge-transfer electronic states appearing at the donor-acceptor interfaces in organic solar cells mediate exciton dissociation, charge generation, and charge recombination. To date, the characterization of their nature has been carried out on the basis of models that only involve the charge-transfer state and the ground state. Here, we demonstrate that it is essential to go beyond such a two-state model and to consider explicitly as well the electronic and vibrational couplings with the local absorbing state on the donor and/or acceptor. We have thus developed a three-state vibronic model that allows us: to provide a reliable description of the optical absorption features related to the charge-transfer states; to underline the erroneous interpretations stemming from the application of the semi-classical two-state model; and to rationalize how the hybridization between the local-excitation state and charge-transfer state can lead to lower non-radiative voltage losses and higher power conversion efficiencies. Previous descriptions of the charge-transfer absorptions in organic solar cells only involve the charge transfer state and the ground state. Here Chen et al. underline that a third state, i.e., the local absorbing state on the donor and/or acceptor, needs to be considered.
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Affiliation(s)
- Xian-Kai Chen
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA
| | - Veaceslav Coropceanu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA.
| | - Jean-Luc Brédas
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA.
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9
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Makha M, Schwaller P, Strassel K, Anantharaman SB, Nüesch F, Hany R, Heier J. Insights into photovoltaic properties of ternary organic solar cells from phase diagrams. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2018; 19:669-682. [PMID: 30275915 PMCID: PMC6161617 DOI: 10.1080/14686996.2018.1509275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/04/2018] [Accepted: 08/05/2018] [Indexed: 06/08/2023]
Abstract
The efficiency of ternary organic solar cells relies on the spontaneous establishment of a nanostructured network of donor and acceptor phases during film formation. A fundamental understanding of phase composition and arrangement and correlations to photovoltaic device parameters is of utmost relevance for both science and technology. We demonstrate a general approach to understanding solar cell behavior from simple thermodynamic principles. For two ternary blend systems we construct and model phase diagrams. Details of EQE and solar cell parameters can be understood from the phase behavior. Our blend system is composed of PC70BM, PBDTTT-C and a near-infrared absorbing cyanine dye. Cyanine dyes are accompanied by counterions, which, in a first approximation, do not change the photophysical properties of the dye, but strongly influence the morphology of the ternary blend. We argue that counterion dissociation is responsible for different mixing behavior. For the dye with a hexafluorophosphate counterion a hierarchical morphology develops, the dye phase separates on a large scale from PC70BM and cannot contribute to photocurrent. Differently, a cyanine dye with a TRISPHAT counterion shows partial miscibility with PC70BM. A large two-phase region dictated by the PC70BM: PBDTTT-C mixture is present and the dye greatly contributes to the short-circuit current.
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Affiliation(s)
- Mohammed Makha
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
| | - Philippe Schwaller
- Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
| | - Karen Strassel
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
| | - Surendra B. Anantharaman
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
- Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
| | - Frank Nüesch
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
- Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
| | - Roland Hany
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
| | - Jakob Heier
- Laboratory for Functional Polymers, Empa, Swiss Federal Institute for Materials Science and Technology, Dübendorf, Switzerland
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10
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Tang Z, Ma Z, Sánchez-Díaz A, Ullbrich S, Liu Y, Siegmund B, Mischok A, Leo K, Campoy-Quiles M, Li W, Vandewal K. Polymer:Fullerene Bimolecular Crystals for Near-Infrared Spectroscopic Photodetectors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1702184. [PMID: 28675522 DOI: 10.1002/adma.201702184] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/06/2017] [Indexed: 05/25/2023]
Abstract
Spectroscopic photodetection is a powerful tool in disciplines such as medical diagnosis, industrial process monitoring, or agriculture. However, its application in novel fields, including wearable and biointegrated electronics, is hampered by the use of bulky dispersive optics. Here, solution-processed organic donor-acceptor blends are employed in a resonant optical cavity device architecture for wavelength-tunable photodetection. While conventional photodetectors respond to above-gap excitation, the cavity device exploits weak subgap absorption of intermolecular charge-transfer states of the intercalating poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bimolecular crystal. This enables a highly wavelength selective, near-infrared photoresponse with a spectral resolution down to 14 nm, as well as dark currents and detectivities comparable with commercial inorganic photodetectors. Based on this concept, a miniaturized spectrophotometer, comprising an array of narrowband cavity photodetectors, is fabricated by using a blade-coated PBTTT:PCBM thin film with a thickness gradient. As an application example, a measurement of the transmittance spectrum of water by this device is demonstrated.
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Affiliation(s)
- Zheng Tang
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Zaifei Ma
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Antonio Sánchez-Díaz
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, 08193, Spain
| | - Sascha Ullbrich
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Yuan Liu
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Bernhard Siegmund
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Andreas Mischok
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Karl Leo
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
| | - Mariano Campoy-Quiles
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, 08193, Spain
| | - Weiwei Li
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 10090, P. R. China
| | - Koen Vandewal
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, 01187, Germany
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11
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Siegmund B, Mischok A, Benduhn J, Zeika O, Ullbrich S, Nehm F, Böhm M, Spoltore D, Fröb H, Körner C, Leo K, Vandewal K. Organic narrowband near-infrared photodetectors based on intermolecular charge-transfer absorption. Nat Commun 2017; 8:15421. [PMID: 28580934 PMCID: PMC5465315 DOI: 10.1038/ncomms15421] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 03/29/2017] [Indexed: 02/08/2023] Open
Abstract
Blending organic electron donors and acceptors yields intermolecular charge-transfer states with additional optical transitions below their optical gaps. In organic photovoltaic devices, such states play a crucial role and limit the operating voltage. Due to its extremely weak nature, direct intermolecular charge-transfer absorption often remains undetected and unused for photocurrent generation. Here, we use an optical microcavity to increase the typically negligible external quantum efficiency in the spectral region of charge-transfer absorption by more than 40 times, yielding values over 20%. We demonstrate narrowband detection with spectral widths down to 36 nm and resonance wavelengths between 810 and 1,550 nm, far below the optical gap of both donor and acceptor. The broad spectral tunability via a simple variation of the cavity thickness makes this innovative, flexible and potentially visibly transparent device principle highly suitable for integrated low-cost spectroscopic near-infrared photodetection. Interfaces of organic donor-acceptor blends provide intermolecular charge-transfer states with red-shifted but weak absorption. By introducing an optical micro-cavity; Siegmund et al., enhance their photoresponse to achieve narrowband NIR photodetection with broad spectral tunability.
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Affiliation(s)
- Bernhard Siegmund
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Andreas Mischok
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Johannes Benduhn
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Olaf Zeika
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Sascha Ullbrich
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Frederik Nehm
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Matthias Böhm
- Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Donato Spoltore
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Hartmut Fröb
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Christian Körner
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Karl Leo
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
| | - Koen Vandewal
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany.,Institute for Applied Physics, Technische Universität Dresden, George-Bähr-Straße 1, Dresden 01062, Germany
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12
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Nikolka M, Nasrallah I, Rose B, Ravva MK, Broch K, Sadhanala A, Harkin D, Charmet J, Hurhangee M, Brown A, Illig S, Too P, Jongman J, McCulloch I, Bredas JL, Sirringhaus H. High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives. NATURE MATERIALS 2017; 16:356-362. [PMID: 27941806 DOI: 10.1038/nmat4785] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 09/23/2016] [Indexed: 05/22/2023]
Abstract
Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.
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Affiliation(s)
- Mark Nikolka
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Iyad Nasrallah
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Bradley Rose
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Mahesh Kumar Ravva
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Katharina Broch
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Aditya Sadhanala
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - David Harkin
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Jerome Charmet
- Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
| | - Michael Hurhangee
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
| | - Adam Brown
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Steffen Illig
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Patrick Too
- FlexEnable Ltd, 34 Cambridge Science Park, Cambridge CB4 0FX, UK
| | - Jan Jongman
- FlexEnable Ltd, 34 Cambridge Science Park, Cambridge CB4 0FX, UK
| | - Iain McCulloch
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK
| | - Jean-Luc Bredas
- Solar &Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Henning Sirringhaus
- Optoelectronics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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13
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The fate of electron-hole pairs in polymer:fullerene blends for organic photovoltaics. Nat Commun 2016; 7:12556. [PMID: 27586309 PMCID: PMC5025766 DOI: 10.1038/ncomms12556] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 07/14/2016] [Indexed: 12/26/2022] Open
Abstract
There has been long-standing debate on how free charges are generated in donor:acceptor blends that are used in organic solar cells, and which are generally comprised of a complex phase morphology, where intermixed and neat phases of the donor and acceptor material co-exist. Here we resolve this question, basing our conclusions on Stark effect spectroscopy data obtained in the absence and presence of externally applied electric fields. Reconciling opposing views found in literature, we unambiguously demonstrate that the fate of photogenerated electron–hole pairs—whether they will dissociate to free charges or geminately recombine—is determined at ultrafast times, despite the fact that their actual spatial separation can be much slower. Our insights are important to further develop rational approaches towards material design and processing of organic solar cells, assisting to realize their purported promise as lead-free, third-generation energy technology that can reach efficiencies over 10%. Charge generation and transport are crucial to the performance of organic solar cells, but the mechanism remains controversial. Causa' et al. show that the phase morphology of polymer:fullerene blends determines the exciton dissociation at femtoseconds, although the spatial separation can occur at picoseconds.
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14
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Ryno SM, Fu YT, Risko C, Brédas JL. Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2016; 8:15524-15534. [PMID: 27244215 DOI: 10.1021/acsami.6b02851] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We probe the energetic landscape at a model pentacene/fullerene (C60) interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e., the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges results in a barrier to charge separation at the pentacene/C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.
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Affiliation(s)
- Sean M Ryno
- Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology , Thuwal 23599-6900, Kingdom of Saudi Arabia
- School of Chemistry and Biochemistry & Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Yao-Tsung Fu
- School of Chemistry and Biochemistry & Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Chad Risko
- Department of Chemistry & Center for Applied Energy Research, University of Kentucky , Lexington, Kentucky 40506-0055, United States
| | - Jean-Luc Brédas
- Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology , Thuwal 23599-6900, Kingdom of Saudi Arabia
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15
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Shiokawa N, Tokunaga E. Quasi first-order Hermite Gaussian beam for enhanced sensitivity in Sagnac interferometer photothermal deflection spectroscopy. OPTICS EXPRESS 2016; 24:11961-11974. [PMID: 27410118 DOI: 10.1364/oe.24.011961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The detection sensitivity of a Sagnac interferometer photothermal deflection spectroscopy was enhanced by changing the probe beam pattern from zero-order to a quasi-first-order Hermite Gaussian (QHG) beam. The nature of the higher order HG mode, where the beam pattern is preserved during propagation with an increased field gradient, is utilized to enhance the measurement sensitivity. In this spectroscopy, the lateral beam deflection due to the photothermal effect is sensitively detected as a change in the interference light intensity. The change in intensity is amplified due to the higher field gradient of the QHG(1,0) beam at the photodetector. This amplification effect was both numerically and experimentally demonstrated to obtain twofold improvement in the signal-to-noise ratio.
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16
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Yao J, Yu C, Liu Z, Luo H, Yang Y, Zhang G, Zhang D. Significant Improvement of Semiconducting Performance of the Diketopyrrolopyrrole–Quaterthiophene Conjugated Polymer through Side-Chain Engineering via Hydrogen-Bonding. J Am Chem Soc 2015; 138:173-85. [DOI: 10.1021/jacs.5b09737] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jingjing Yao
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Chenmin Yu
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zitong Liu
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Hewei Luo
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yang Yang
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Guanxin Zhang
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Deqing Zhang
- Beijing National Laboratory
for Molecular Sciences, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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