51
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Few S, Chia C, Teo D, Kirkpatrick J, Nelson J. The impact of chemical structure and molecular packing on the electronic polarisation of fullerene arrays. Phys Chem Chem Phys 2018; 19:18709-18720. [PMID: 28696470 DOI: 10.1039/c7cp00317j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic polarisation contributes to the electronic landscape as seen by separating charges in organic materials. The nature of electronic polarisation depends on the polarisability, density, and arrangement of polarisable molecules. In this paper, we introduce a microscopic, coarse-grained model in which we treat each molecule as a polarisable site, and use an array of such polarisable dipoles to calculate the electric field and associated energy of any arrangement of charges in the medium. The model incorporates chemical structure via the molecular polarisability and molecular packing patterns via the structure of the array. We use this model to calculate energies of charge pairs undergoing separation in finite fullerene lattices of different chemical and crystal structures. The effective dielectric constants that we estimate from this approach are in good quantitative agreement with those measured experimentally in C60 and phenyl-C61-butyric acid methyl ester (PCBM) films, but we find significant differences in dielectric constant depending on packing and on direction of separation, which we rationalise in terms of density of polarisable fullerene cages in regions of high field. In general, we find lattices containing molecules of more isotropic polarisability tensors exhibit higher dielectric constants. By exploring several model systems we conclude that differences in molecular polarisability (and therefore, chemical structure) appear to be less important than differences in molecular packing and separation direction in determining the energetic landscape for charge separation. We note that the results are relevant for finite lattices, but not necessarily for infinite systems. We propose that the model could be used to design molecular systems for effective electronic screening.
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Affiliation(s)
- Sheridan Few
- Centre for Plastic Electronics, Department of Physics, Imperial College London, London SW7 2AZ, UK.
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52
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Steyrleuthner R, Zhang Y, Zhang L, Kraffert F, Cherniawski BP, Bittl R, Briseno AL, Bredas JL, Behrends J. Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer. Phys Chem Chem Phys 2018; 19:3627-3639. [PMID: 28094360 DOI: 10.1039/c6cp07485e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the delocalization of holes in the semicrystalline conjugated polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) by directly measuring the hyperfine coupling between photogenerated polarons and bound nuclear spins using electron nuclear double resonance spectroscopy. An extrapolation of the corresponding oligomer spectra reveals that charges tend to delocalize over 4.0-4.8 nm with delocalization strongly dependent on molecular order and crystallinity of the PBTTT polymer thin films. Density functional theory calculations of hyperfine couplings confirm that long-range corrected functionals appropriately describe the change in coupling strength with increasing oligomer size and agree well with the experimentally measured polymer limit. Our discussion presents general guidelines illustrating the various pitfalls and opportunities when deducing polaron localization lengths from hyperfine coupling spectra of conjugated polymers.
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Affiliation(s)
- Robert Steyrleuthner
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Yuexing Zhang
- King Abdullah University of Science & Technology, Solar & Photovoltaics Engineering Research Center, Thuwal 23955-6900, Saudi Arabia and Department of Chemistry, Hubei University, Wuhan 430062, China
| | - Lei Zhang
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Felix Kraffert
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Benjamin P Cherniawski
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Robert Bittl
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Alejandro L Briseno
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Jean-Luc Bredas
- King Abdullah University of Science & Technology, Solar & Photovoltaics Engineering Research Center, Thuwal 23955-6900, Saudi Arabia
| | - Jan Behrends
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
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53
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Zhang J, Gu Q, Do TT, Rundel K, Sonar P, Friend RH, McNeill CR, Bakulin AA. Control of Geminate Recombination by the Material Composition and Processing Conditions in Novel Polymer: Nonfullerene Acceptor Photovoltaic Devices. J Phys Chem A 2018; 122:1253-1260. [DOI: 10.1021/acs.jpca.7b11891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jiangbin Zhang
- Department
of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Qinying Gu
- Department
of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
- Department
of Materials Science and Engineering, Monash University, Wellington
Road, Clayton, Victoria 3800, Australia
| | - Thu Trang Do
- School
of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia
| | - Kira Rundel
- Department
of Materials Science and Engineering, Monash University, Wellington
Road, Clayton, Victoria 3800, Australia
| | - Prashant Sonar
- School
of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001, Australia
| | - Richard H. Friend
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Christopher R. McNeill
- Department
of Materials Science and Engineering, Monash University, Wellington
Road, Clayton, Victoria 3800, Australia
| | - Artem A. Bakulin
- Department
of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
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54
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Nan G, Zhang X, Lu G. The lowest-energy charge-transfer state and its role in charge separation in organic photovoltaics. Phys Chem Chem Phys 2018; 18:17546-56. [PMID: 27306609 DOI: 10.1039/c6cp01622g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Energy independent, yet higher than 90% internal quantum efficiency (IQE), has been observed in many organic photovoltaics (OPVs). However, its physical origin remains largely unknown and controversial. The hypothesis that the lowest charge-transfer (CT) state may be weakly bound at the interface has been proposed to rationalize the experimental observations. In this paper, we study the nature of the lowest-energy CT (CT1) state, and show conclusively that the CT1 state is localized in typical OPVs. The electronic couplings in the donor and acceptor are found to determine the localization of the CT1 state. We examine the geminate recombination of the CT1 state and estimate its lifetime from first principles. We identify the vibrational modes that contribute to the geminate recombination. Using material parameters determined from first principles and experiments, we carry out kinetic Monte Carlo simulations to examine the charge separation of the localized CT1 state. We find that the localized CT1 state can indeed yield efficient charge separation with IQE higher than 90%. Dynamic disorder and configuration entropy can provide the energetic and entropy driving force for charge separation. Charge separation efficiency depends more sensitively on the dimension and crystallinity of the acceptor parallel to the interface than that normal to the interface. Reorganization energy is found to be the most important material parameter for charge separation, and lowering the reorganization energy of the donor should be pursued in the materials design.
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Affiliation(s)
- Guangjun Nan
- Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, California 91330-8268, USA.
| | - Xu Zhang
- Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, California 91330-8268, USA.
| | - Gang Lu
- Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, California 91330-8268, USA.
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55
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Hou J, Inganäs O, Friend RH, Gao F. Organic solar cells based on non-fullerene acceptors. NATURE MATERIALS 2018; 17:119-128. [PMID: 29358765 DOI: 10.1038/nmat5063] [Citation(s) in RCA: 879] [Impact Index Per Article: 146.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/06/2017] [Indexed: 05/19/2023]
Abstract
Organic solar cells (OSCs) have been dominated by donor:acceptor blends based on fullerene acceptors for over two decades. This situation has changed recently, with non-fullerene (NF) OSCs developing very quickly. The power conversion efficiencies of NF OSCs have now reached a value of over 13%, which is higher than the best fullerene-based OSCs. NF acceptors show great tunability in absorption spectra and electron energy levels, providing a wide range of new opportunities. The coexistence of low voltage losses and high current generation indicates that new regimes of device physics and photophysics are reached in these systems. This Review highlights these opportunities made possible by NF acceptors, and also discuss the challenges facing the development of NF OSCs for practical applications.
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Affiliation(s)
- Jianhui Hou
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Olle Inganäs
- Biomolecular and organic electronics, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-58183, Sweden
| | | | - Feng Gao
- Biomolecular and organic electronics, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-58183, Sweden
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56
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Order enables efficient electron-hole separation at an organic heterojunction with a small energy loss. Nat Commun 2018; 9:277. [PMID: 29348491 PMCID: PMC5773693 DOI: 10.1038/s41467-017-02457-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/03/2017] [Indexed: 11/08/2022] Open
Abstract
Donor-acceptor organic solar cells often show low open-circuit voltages (V OC) relative to their optical energy gap (E g) that limit power conversion efficiencies to ~12%. This energy loss is partly attributed to the offset between E g and that of intermolecular charge transfer (CT) states at the donor-acceptor interface. Here we study charge generation occurring in PIPCP:PC61BM, a system with a very low driving energy for initial charge separation (E g-E CT ~ 50 meV) and a high internal quantum efficiency (η IQE ~ 80%). We track the strength of the electric field generated between the separating electron-hole pair by following the transient electroabsorption optical response, and find that while localised CT states are formed rapidly (<100 fs) after photoexcitation, free charges are not generated until 5 ps after photogeneration. In PIPCP:PC61BM, electronic disorder is low (Urbach energy <27 meV) and we consider that free charge separation is able to outcompete trap-assisted non-radiative recombination of the CT state.
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57
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Bolognesi M, Gedefaw D, Cavazzini M, Catellani M, Andersson MR, Muccini M, Kozma E, Seri M. Side chain modification on PDI-spirobifluorene-based molecular acceptors and its impact on organic solar cell performances. NEW J CHEM 2018. [DOI: 10.1039/c8nj04810j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N-Substitution in perylene diimide (PDI) n-type semiconductors is critical for their performance in organic bulk heterojunction solar cells.
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Affiliation(s)
- Margherita Bolognesi
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)
- Consiglio Nazionale delle Ricerche (CNR)
- 40129 Bologna
- Italy
| | - Desta Gedefaw
- School of Biological and Chemical Sciences
- The University of South Pacific
- Laucala Campus
- Suva
- Fiji
| | - Marco Cavazzini
- Istituto di Scienze e Tecnologie Molecolari (ISTM)
- Consiglio Nazionale delle Ricerche (CNR)
- Dipartimento di Chimica Organica e Industriale
- Università degli Studi di Milano
- 20133 Milano
| | - Marinella Catellani
- Istituto per lo Studio delle Macromolecole (ISMAC)
- Consiglio Nazionale delle Ricerche (CNR)
- 20133 Milano
- Italy
| | - Mats R. Andersson
- Flinders Institute for NanoScale Science and Technology
- Flinders University
- Bedford Park
- Australia
| | - Michele Muccini
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)
- Consiglio Nazionale delle Ricerche (CNR)
- 40129 Bologna
- Italy
| | - Erika Kozma
- Istituto per lo Studio delle Macromolecole (ISMAC)
- Consiglio Nazionale delle Ricerche (CNR)
- 20133 Milano
- Italy
| | - Mirko Seri
- Istituto per la Sintesi Organica e la Fotoreattività (ISOF)
- Consiglio Nazionale delle Ricerche (CNR)
- 40129 Bologna
- Italy
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58
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Zhang Y, Parnell AJ, Blaszczyk O, Musser AJ, Samuel IDW, Lidzey DG, Bernardo G. Effect of fullerene acceptor on the performance of solar cells based on PffBT4T-2OD. Phys Chem Chem Phys 2018; 20:19023-19029. [DOI: 10.1039/c8cp02195c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have studied organic solar cells composed of PffBT4T-2OD as electron donor and three different electron accepting fullerenes, in order to understand the impact of different fullerenes on the morphology and efficiency of the corresponding photovoltaic devices.
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Affiliation(s)
- Yiwei Zhang
- Department of Physics and Astronomy
- The University of Sheffield
- UK
- Organic Semiconductor Centre
- SUPA
| | | | - Oskar Blaszczyk
- Organic Semiconductor Centre
- SUPA
- School of Physics & Astronomy
- University of St Andrews
- St Andrews KY16 9SS
| | - Andrew J. Musser
- Department of Physics and Astronomy
- The University of Sheffield
- UK
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre
- SUPA
- School of Physics & Astronomy
- University of St Andrews
- St Andrews KY16 9SS
| | - David G. Lidzey
- Department of Physics and Astronomy
- The University of Sheffield
- UK
| | - Gabriel Bernardo
- Department of Physics and Astronomy
- The University of Sheffield
- UK
- LEPABE
- Department of Chemical Engineering
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59
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Tamai Y, Fan Y, Kim VO, Ziabrev K, Rao A, Barlow S, Marder SR, Friend RH, Menke SM. Ultrafast Long-Range Charge Separation in Nonfullerene Organic Solar Cells. ACS NANO 2017; 11:12473-12481. [PMID: 29148715 DOI: 10.1021/acsnano.7b06575] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Rapid, long-range charge separation in polymer-fullerene organic solar cells (OSCs) enables electrons and holes to move beyond their Coulomb capture radius and overcome geminate recombination. Understanding the nature of charge generation and recombination mechanisms in efficient, nonfullerene-acceptor-based OSCs are critical to further improve device performance. Here we report charge dynamics in an OSC using a perylene diimide (PDI) dimer acceptor. We use transient absorption spectroscopy to track the time evolution of electroabsorption caused by the dipolar electric field generated between electron-hole pairs as they separate after ionization at the donor-acceptor interface. We show that charges separate rapidly (<1 ps) and that free charge carriers are generated very efficiently (∼90% quantum yield). However, in the PDI-based OSC, external charge extraction is impaired by faster nongeminate decay to the ground state and to lower-lying triplet states.
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Affiliation(s)
- Yasunari Tamai
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Yeli Fan
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Vincent O Kim
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Kostiantyn Ziabrev
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Akshay Rao
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Stephen Barlow
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Seth R Marder
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Richard H Friend
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - S Matthew Menke
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
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60
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Liu F, Hou T, Xu X, Sun L, Zhou J, Zhao X, Zhang S. Recent Advances in Nonfullerene Acceptors for Organic Solar Cells. Macromol Rapid Commun 2017; 39. [DOI: 10.1002/marc.201700555] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/24/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Fuchuan Liu
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM); Nanjing Tech University (Nanjing Tech); 30 South Puzhu Road Nanjing 211816 P. R. China
| | - Tianyu Hou
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM); Nanjing Tech University (Nanjing Tech); 30 South Puzhu Road Nanjing 211816 P. R. China
| | - Xiangfei Xu
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM); Nanjing Tech University (Nanjing Tech); 30 South Puzhu Road Nanjing 211816 P. R. China
| | - Liya Sun
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM); Nanjing Tech University (Nanjing Tech); 30 South Puzhu Road Nanjing 211816 P. R. China
| | - Jiawang Zhou
- Department of Chemistry; Johns Hopkins University; 3400 North Charles Street Baltimore MD 21218 USA
| | - Xingang Zhao
- Department of Materials Science and Engineering; Johns Hopkins University; 3400 North Charles Street Baltimore MD 21218 USA
| | - Shiming Zhang
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM); Nanjing Tech University (Nanjing Tech); 30 South Puzhu Road Nanjing 211816 P. R. China
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61
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Cao B, He X, Sorge JB, Lalany A, Ahadi K, Afshar A, Olsen BC, Hauger TC, Mobarok MH, Li P, Cadien KC, Brett MJ, Luber EJ, Buriak JM. Understanding the Effects of a High Surface Area Nanostructured Indium Tin Oxide Electrode on Organic Solar Cell Performance. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38706-38715. [PMID: 29022714 DOI: 10.1021/acsami.7b10610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Organic solar cells (OSCs) are a complex assembly of disparate materials, each with a precise function within the device. Typically, the electrodes are flat, and the device is fabricated through a layering approach of the interfacial layers and photoactive materials. This work explores the integration of high surface area transparent electrodes to investigate the possible role(s) a three-dimensional electrode could take within an OSC, with a BHJ composed of a donor-acceptor combination with a high degree of electron and hole mobility mismatch. Nanotree indium tin oxide (ITO) electrodes were prepared via glancing angle deposition, structures that were previously demonstrated to be single-crystalline. A thin layer of zinc oxide was deposited on the ITO nanotrees via atomic layer deposition, followed by a self-assembled monolayer of C60-based molecules that was bound to the zinc oxide surface through a carboxylic acid group. Infiltration of these functionalized ITO nanotrees with the photoactive layer, the bulk heterojunction comprising PC71BM and a high hole mobility low band gap polymer (PDPPTT-T-TT), led to families of devices that were analyzed for the effect of nanotree height. When the height was varied from 0 to 50, 75, 100, and 120 nm, statistically significant differences in device performance were noted with the maximum device efficiencies observed with a nanotree height of 75 nm. From analysis of these results, it was found that the intrinsic mobility mismatch between the donor and acceptor phases could be compensated for when the electron collection length was reduced relative to the hole collection length, resulting in more balanced charge extraction and reduced recombination, leading to improved efficiencies. However, as the ITO nanotrees increased in height and branching, the decrease in electron collection length was offset by an increase in hole collection length and potential deleterious electric field redistribution effects, resulting in decreased efficiency.
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Affiliation(s)
- Bing Cao
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Xiaoming He
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Jason B Sorge
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Abeed Lalany
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Kaveh Ahadi
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Amir Afshar
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Brian C Olsen
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Tate C Hauger
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Md Hosnay Mobarok
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Peng Li
- nanoFAB Centre, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Kenneth C Cadien
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Michael J Brett
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Erik J Luber
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Jillian M Buriak
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
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62
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Logsdon JL, Hartnett PE, Nelson JN, Harris MA, Marks TJ, Wasielewski MR. Charge Separation Mechanisms in Ordered Films of Self-Assembled Donor-Acceptor Dyad Ribbons. ACS APPLIED MATERIALS & INTERFACES 2017; 9:33493-33503. [PMID: 28430417 DOI: 10.1021/acsami.7b02585] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Orthogonal attachment of polar and nonpolar side-chains to a zinc porphyrin-perylenediimide dyad (ZnP-PDI, 1a) is shown to result in self-assembly of ordered supramolecular ribbons in which the ZnP and PDI molecules form segregated π-stacked columns. Following photoexcitation of the ordered ribbons, ZnP+•-PDI-• radical ion pairs form in <200 fs and subsequently produce a 30 ± 3% yield of free charge carriers that live for about 100 μs. Elongating the side chains on ZnP and PDI in 1b enhances the order of the films, but does not result in an increase in free charge carrier yield. In addition, this yield is independent of temperature, free energy of reaction, and the ZnP-PDI distance in the covalent dyad. These results suggest that the free charge carrier yield in this system is not limited by a bound charge transfer (CT) state or promoted by a vibronically hot CT state. Instead, it is likely that π-stacking of the segregated donors and acceptors within the ribbons results in delocalization of the charges following photoexcitation, allowing them to overcome Coulombic attraction and generate free charge carriers.
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Affiliation(s)
- Jenna L Logsdon
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Patrick E Hartnett
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Jordan N Nelson
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michelle A Harris
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Tobin J Marks
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
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63
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Collado-Fregoso E, Hood SN, Shoaee S, Schroeder BC, McCulloch I, Kassal I, Neher D, Durrant JR. Intercalated vs Nonintercalated Morphologies in Donor-Acceptor Bulk Heterojunction Solar Cells: PBTTT:Fullerene Charge Generation and Recombination Revisited. J Phys Chem Lett 2017; 8:4061-4068. [PMID: 28777583 DOI: 10.1021/acs.jpclett.7b01571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this Letter, we study the role of the donor:acceptor interface nanostructure upon charge separation and recombination in organic photovoltaic devices and blend films, using mixtures of PBTTT and two different fullerene derivatives (PC70BM and ICTA) as models for intercalated and nonintercalated morphologies, respectively. Thermodynamic simulations show that while the completely intercalated system exhibits a large free-energy barrier for charge separation, this barrier is significantly lower in the nonintercalated system and almost vanishes when energetic disorder is included in the model. Despite these differences, both femtosecond-resolved transient absorption spectroscopy (TAS) and time-delayed collection field (TDCF) exhibit extensive first-order losses in both systems, suggesting that geminate pairs are the primary product of photoexcitation. In contrast, the system that comprises a combination of fully intercalated polymer:fullerene areas and fullerene-aggregated domains (1:4 PBTTT:PC70BM) is the only one that shows slow, second-order recombination of free charges, resulting in devices with an overall higher short-circuit current and fill factor. This study therefore provides a novel consideration of the role of the interfacial nanostructure and the nature of bound charges and their impact upon charge generation and recombination.
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Affiliation(s)
- Elisa Collado-Fregoso
- Department of Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
- Centre for Plastic Electronics, Department of Chemistry, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Samantha N Hood
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Safa Shoaee
- Department of Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
| | - Bob C Schroeder
- Materials Research Institute and School of Biological and Chemical Sciences, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
- Centre for Plastic Electronics, Department of Chemistry, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
| | - Iain McCulloch
- Centre for Plastic Electronics, Department of Chemistry, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
- KSC, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Ivan Kassal
- Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland , Brisbane, Queensland 4072, Australia
- Centre for Engineered Quantum Systems, Australian Institute for Nanoscale Science and Technology, and School of Chemistry, The University of Sydney , Sydney, New South Wales 2006, Australia
| | - Dieter Neher
- Department of Physics and Astronomy, University of Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
| | - James R Durrant
- Centre for Plastic Electronics, Department of Chemistry, Imperial College London , Exhibition Road, London SW7 2AZ, United Kingdom
- SPECIFIC IKC, College of Engineering, Swansea University , Swansea SA12 7AX, United Kingdom
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64
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Ponseca CS, Chábera P, Uhlig J, Persson P, Sundström V. Ultrafast Electron Dynamics in Solar Energy Conversion. Chem Rev 2017; 117:10940-11024. [DOI: 10.1021/acs.chemrev.6b00807] [Citation(s) in RCA: 211] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Carlito S. Ponseca
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Pavel Chábera
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Jens Uhlig
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Petter Persson
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Villy Sundström
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
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65
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Nakano K, Tajima K. Organic Planar Heterojunctions: From Models for Interfaces in Bulk Heterojunctions to High-Performance Solar Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1603269. [PMID: 27885716 DOI: 10.1002/adma.201603269] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/30/2016] [Indexed: 05/28/2023]
Abstract
Recent progress regarding planar heterojunctions (PHJs) is reviewed, with respect to the fundamental understanding of the photophysical processes at the donor/acceptor interfaces in organic photovoltaic devices (OPVs). The current state of OPV research is summarized and the advantages of PHJs as models for exploring the relationship between organic interfaces and device characteristics described. The preparation methods and the characterization of PHJ structures to provide key points for the appropriate handling of PHJs. Next, we describe the effects of the donor/acceptor interface on each photoelectric conversion process are reviewed by examining various PHJ systems to clarify what is currently known and not known. Finally, it is discussed how we the knowledge obtained by studies of PHJs can be used to overcome the current limits of OPV efficiency.
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Affiliation(s)
- Kyohei Nakano
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Keisuke Tajima
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
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66
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Zheng Z, Tummala NR, Fu YT, Coropceanu V, Brédas JL. Charge-Transfer States in Organic Solar Cells: Understanding the Impact of Polarization, Delocalization, and Disorder. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18095-18102. [PMID: 28481497 DOI: 10.1021/acsami.7b02193] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We investigate the impact of electronic polarization, charge delocalization, and energetic disorder on the charge-transfer (CT) states formed at a planar C60/pentacene interface. The ability to examine large complexes containing up to seven pentacene molecules and three C60 molecules allows us to take explicitly into account the electronic polarization effects. These complexes are extracted from a bilayer architecture modeled by molecular dynamics simulations and evaluated by means of electronic-structure calculations based on long-range-separated functionals (ωB97XD and BNL) with optimized range-separation parameters. The energies of the lowest charge-transfer states derived for the large complexes are in very good agreement with the experimentally reported values. The average singlet-triplet energy splittings of the lowest CT states are calculated not to exceed 10 meV. The rates of geminate recombination as well as of dissociation of the triplet excitons are also evaluated. In line with experiment, our results indicate that the pentacene triplet excitons generated through singlet fission can dissociate into separated charges on a picosecond time scale, despite the fact that their energy in C60/pentacene heterojunctions is slightly lower than the energies of the lowest CT triplet states.
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Affiliation(s)
- Zilong Zheng
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Naga Rajesh Tummala
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Yao-Tsung Fu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Veaceslav Coropceanu
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Jean-Luc Brédas
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
- KAUST Solar Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
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67
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Athanasopoulos S, Tscheuschner S, Bässler H, Köhler A. Efficient Charge Separation of Cold Charge-Transfer States in Organic Solar Cells Through Incoherent Hopping. J Phys Chem Lett 2017; 8:2093-2098. [PMID: 28436660 DOI: 10.1021/acs.jpclett.7b00595] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate that efficient and nearly field-independent charge separation of electron-hole pairs in organic planar heterojunction solar cells can be described by an incoherent hopping mechanism. Using kinetic Monte Carlo simulations that include the effect of on-chain delocalization as well as entropic contributions, we simulate the dissociation of the charge-transfer state in polymer-fullerene bilayer solar cells. The model further explains experimental results of almost field independent charge separation in bilayers of molecular systems with fullerenes and provides important guidelines at the molecular level for maximizing the efficiencies of organic solar cells. Thus, utilizing coherent phenomena is not necessarily required for highly efficient charge separation in organic solar cells.
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Affiliation(s)
- Stavros Athanasopoulos
- Departamento de Física, Universidad Carlos III de Madrid , Avenida Universidad 30, Leganés 28911, Madrid, Spain
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68
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Kästner C, Vandewal K, Egbe DAM, Hoppe H. Revelation of Interfacial Energetics in Organic Multiheterojunctions. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2017; 4:1600331. [PMID: 28435774 PMCID: PMC5396163 DOI: 10.1002/advs.201600331] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/29/2016] [Indexed: 06/07/2023]
Abstract
Efficient charge generation via exciton dissociation in organic bulk heterojunctions necessitates donor-acceptor interfaces, e.g., between a conjugated polymer and a fullerene derivative. Furthermore, aggregation and corresponding structural order of polymer and fullerene domains result in energetic relaxations of molecular energy levels toward smaller energy gaps as compared to the situation for amorphous phases existing in homogeneously intermixed polymer:fullerene blends. Here it is shown that these molecular energy level shifts are reflected in interfacial charge transfer (CT) transitions and depending on the existence of disordered or ordered interfacial domains. It can be done so by systematically controlling the order at the donor-acceptor interface via ternary blending of semicrystalline and amorphous model polymers with a fullerene acceptor. These variations in interfacial domain order are probed with luminescence spectroscopy, yielding various transition energies due to activation of different recombination channels at the interface. Finally, it is shown that via this analysis the energy landscape at the organic heterojunction interface can be obtained.
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Affiliation(s)
- Christian Kästner
- Institute of PhysicsTechnische Universität IlmenauWeimarer Str. 3298693IlmenauGermany
| | - Koen Vandewal
- Institut für Angewandte PhotophysikTechnische Universität DresdenGeorge‐Bähr‐Str. 101069DresdenGermany
| | - Daniel Ayuk Mbi Egbe
- Institute of Polymeric Materials and TestingJohannes Kepler University LinzAltenbergerstr. 694040LinzAustria
| | - Harald Hoppe
- Institute of PhysicsTechnische Universität IlmenauWeimarer Str. 3298693IlmenauGermany
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69
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Wang T, Kafle TR, Kattel B, Chan WL. A Multidimensional View of Charge Transfer Excitons at Organic Donor–Acceptor Interfaces. J Am Chem Soc 2017; 139:4098-4106. [DOI: 10.1021/jacs.6b13312] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ti Wang
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Tika R. Kafle
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Bhupal Kattel
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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70
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Groves C. Simulating charge transport in organic semiconductors and devices: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:026502. [PMID: 27991440 DOI: 10.1088/1361-6633/80/2/026502] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Charge transport simulation can be a valuable tool to better understand, optimise and design organic transistors (OTFTs), photovoltaics (OPVs), and light-emitting diodes (OLEDs). This review presents an overview of common charge transport and device models; namely drift-diffusion, master equation, mesoscale kinetic Monte Carlo and quantum chemical Monte Carlo, and a discussion of the relative merits of each. This is followed by a review of the application of these models as applied to charge transport in organic semiconductors and devices, highlighting in particular the insights made possible by modelling. The review concludes with an outlook for charge transport modelling in organic electronics.
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Affiliation(s)
- C Groves
- Durham University, School of Engineering and Computing Sciences, South Road, Durham, DH1 3LE, UK
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71
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Hartnett PE, Mauck CM, Harris MA, Young RM, Wu YL, Marks TJ, Wasielewski MR. Influence of Anion Delocalization on Electron Transfer in a Covalent Porphyrin Donor–Perylenediimide Dimer Acceptor System. J Am Chem Soc 2017; 139:749-756. [DOI: 10.1021/jacs.6b10140] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick E. Hartnett
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Catherine M. Mauck
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michelle A. Harris
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ryan M. Young
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yi-Lin Wu
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tobin J. Marks
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael R. Wasielewski
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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72
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Pan QQ, Li SB, Wu Y, Zhang J, Li HB, Geng Y, Zhang M, Su ZM. Theoretical design of three-dimensional non-fullerene acceptor materials based on an arylenediimide unit towards high efficiency organic solar cells. NEW J CHEM 2017. [DOI: 10.1039/c6nj03932d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
DFT and TDDFT calculations were performed to search for high-performance non-fullerene organic acceptor materials in organic solar cells.
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Affiliation(s)
- Qing-Qing Pan
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
| | - Shuang-Bao Li
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
| | - Yong Wu
- School of Pharmaceutical Sciences
- Changchun University of Chinese Medicine
- Changchun
- P. R. China
| | - Ji Zhang
- College of Chemistry and Life Science
- Changchun University of Technology
- ChangChun
- P. R. China
| | - Hai-Bin Li
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
| | - Yun Geng
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
| | - Min Zhang
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
| | - Zhong-Min Su
- Institute of Functional Material Chemistry
- Faculty of Chemistry
- Northeast Normal University
- ChangChun 130024
- P. R. China
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73
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Li X, Tang ML. Triplet transport in thin films: fundamentals and applications. Chem Commun (Camb) 2017; 53:4429-4440. [DOI: 10.1039/c7cc00861a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An overview of experimental and theoretical work on triplet energy transfer, with a focus on triplet transport in thin films.
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Affiliation(s)
- Xin Li
- Chemistry Department
- University of California
- Riverside
- USA
| | - Ming Lee Tang
- Chemistry Department
- University of California
- Riverside
- USA
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74
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Brédas JL, Sargent EH, Scholes GD. Photovoltaic concepts inspired by coherence effects in photosynthetic systems. NATURE MATERIALS 2016; 16:35-44. [PMID: 27994245 DOI: 10.1038/nmat4767] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 09/05/2016] [Indexed: 05/20/2023]
Abstract
The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder - structural and energetic - and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.
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Affiliation(s)
- Jean-Luc Brédas
- Division of Physical Science and Engineering, Solar and Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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75
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Zhang B, Trinh MT, Fowler B, Ball M, Xu Q, Ng F, Steigerwald ML, Zhu XY, Nuckolls C, Zhong Y. Rigid, Conjugated Macrocycles for High Performance Organic Photodetectors. J Am Chem Soc 2016; 138:16426-16431. [DOI: 10.1021/jacs.6b10276] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Boyuan Zhang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - M. Tuan Trinh
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Brandon Fowler
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Melissa Ball
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Qizhi Xu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Fay Ng
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | | | - X.-Y. Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yu Zhong
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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76
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Abstract
![]()
The field of organic
photovoltaics has developed rapidly over the
last 2 decades, and small solar cells with power conversion efficiencies
of 13% have been demonstrated. Light absorbed in the organic layers
forms tightly bound excitons that are split into free electrons and
holes using heterojunctions of electron donor and acceptor materials,
which are then extracted at electrodes to give useful electrical power.
This review gives a concise description of the fundamental processes
in photovoltaic devices, with the main emphasis on the characterization
of energy transfer and its role in dictating device architecture,
including multilayer planar heterojunctions, and on the factors that
impact free carrier generation from dissociated excitons. We briefly
discuss harvesting of triplet excitons, which now attracts substantial
interest when used in conjunction with singlet fission. Finally, we
introduce the techniques used by researchers for characterization
and engineering of bulk heterojunctions to realize large photocurrents,
and examine the formed morphology in three prototypical blends.
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Affiliation(s)
- Gordon J Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
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77
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Purc A, Espinoza EM, Nazir R, Romero JJ, Skonieczny K, Jeżewski A, Larsen JM, Gryko DT, Vullev VI. Gating That Suppresses Charge Recombination-The Role of Mono-N-Arylated Diketopyrrolopyrrole. J Am Chem Soc 2016; 138:12826-12832. [PMID: 27617743 DOI: 10.1021/jacs.6b04974] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Suppressing the charge recombination (CR) that follows an efficient charge separation (CS) is of key importance for energy, electronics, and photonics applications. We focus on the role of dynamic gating for impeding CR in a molecular rotor, comprising an electron donor and acceptor directly linked via a single bond. The media viscosity has an unusual dual effect on the dynamics of CS and CR in this dyad. For solvents with intermediate viscosity, CR is 1.5-3 times slower than CS. Lowering the viscosity below ∼0.6 mPa s or increasing it above ∼10 mPa s makes CR 10-30 times slower than CS. Ring rotation around the donor-acceptor bond can account only for the trends observed for nonviscous solvents. Media viscosity, however, affects not only torsional but also vibrational modes. Suppressing predominantly slow vibrational modes by viscous solvents can impact the rates of CS and CR to a different extent. That is, an increase in the viscosity can plausibly suppress modes that are involved in the transition from the charge-transfer (CT) to the ground state, i.e., CR, but at the same time are not important for the transition from the locally excited to the CT state, i.e., CS. These results provide a unique example of synergy between torsional and vibronic modes and their drastic effects on charge-transfer dynamics, thus setting paradigms for controlling CS and CR.
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Affiliation(s)
- Anna Purc
- Institute of Organic Chemistry, Polish Academy of Sciences , Kasprzaka 44-52, 01-224 Warsaw, Poland
| | | | - Rashid Nazir
- Institute of Organic Chemistry, Polish Academy of Sciences , Kasprzaka 44-52, 01-224 Warsaw, Poland
| | | | - Kamil Skonieczny
- Institute of Organic Chemistry, Polish Academy of Sciences , Kasprzaka 44-52, 01-224 Warsaw, Poland
| | - Artur Jeżewski
- Institute of Organic Chemistry, Polish Academy of Sciences , Kasprzaka 44-52, 01-224 Warsaw, Poland
| | | | - Daniel T Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences , Kasprzaka 44-52, 01-224 Warsaw, Poland
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78
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Jakowetz AC, Böhm ML, Zhang J, Sadhanala A, Huettner S, Bakulin AA, Rao A, Friend RH. What Controls the Rate of Ultrafast Charge Transfer and Charge Separation Efficiency in Organic Photovoltaic Blends. J Am Chem Soc 2016; 138:11672-9. [DOI: 10.1021/jacs.6b05131] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Andreas C. Jakowetz
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
| | - Marcus L. Böhm
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jiangbin Zhang
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
| | - Aditya Sadhanala
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
| | - Sven Huettner
- Fakultät
für Biologie, Chemie und Geowissenschaften, University Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany
| | - Artem A. Bakulin
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
- Department
of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Akshay Rao
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
| | - Richard H. Friend
- Cavendish
Laboratory, Department of Physics, University of Cambridge, J J Thomson
Avenue, Cambridge CB3 0HE, United Kingdom
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79
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Liu X, Ding K, Panda A, Forrest SR. Charge Transfer States in Dilute Donor-Acceptor Blend Organic Heterojunctions. ACS NANO 2016; 10:7619-7626. [PMID: 27487403 DOI: 10.1021/acsnano.6b02865] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the charge transfer (CT) states in small-molecule blend heterojunctions comprising the nonpolar donor, tetraphenyldibenzoperiflanthene (DBP), and the acceptor, C70, using electroluminescence and steady-state and time-resolved photoluminescence spectroscopy along with density functional theory calculations. We find that the CT exciton energy blue shifts as the C70 concentration in the blend is either decreased or increased away from 50 vol %. At 20 K, the increase in CT state lifetime is correlated with the increasing diameter of C70 nanocrystallites in the blends. A quantum confinement model is used to quantitatively describe the dependence of both CT energy and lifetime on the C70 or DBP domain size. Two discrete CT emission peaks are observed for blends whose C70 concentration is >65%, at which point C70 nanocrystallites with diameters >4 nm appear in high-resolution transmission electron micrographs. The presence of two CT states is attributed to coexistence of crystalline C70 and amorphous phases in the blends. Furthermore, analysis of CT dissociation efficiency versus photon energy suggests that the >90% dissociation efficiency of delocalized CT2 states from the crystalline phase significantly contributes to surprisingly efficient photogeneration in highly dilute (>80% C70) DBP/C70 heterojunctions.
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Affiliation(s)
- Xiao Liu
- Department of Electrical Engineering and Computer Science, ‡Department of Physics, and §Departments of Material Science and Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Kan Ding
- Department of Electrical Engineering and Computer Science, ‡Department of Physics, and §Departments of Material Science and Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Anurag Panda
- Department of Electrical Engineering and Computer Science, ‡Department of Physics, and §Departments of Material Science and Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Stephen R Forrest
- Department of Electrical Engineering and Computer Science, ‡Department of Physics, and §Departments of Material Science and Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
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80
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Umeyama T, Miyata T, Jakowetz AC, Shibata S, Kurotobi K, Higashino T, Koganezawa T, Tsujimoto M, Gélinas S, Matsuda W, Seki S, Friend RH, Imahori H. Regioisomer effects of [70]fullerene mono-adduct acceptors in bulk heterojunction polymer solar cells. Chem Sci 2016; 8:181-188. [PMID: 28451164 PMCID: PMC5308288 DOI: 10.1039/c6sc02950g] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 08/06/2016] [Indexed: 01/05/2023] Open
Abstract
Regioisomer separations of [70]fullerene mono-adducts for polymer solar cell (PSC) applications were conducted for the first time.
Despite numerous organic semiconductors being developed during the past decade, C70 derivatives are predominantly used as electron acceptors in efficient polymer solar cells (PSCs). However, as-prepared C70 mono-adducts intrinsically comprise regioisomers that would mask individual device performances depending on the substituent position on C70. Herein, we separate the regioisomers of C70 mono-adducts for PSC applications for the first time. Systematic investigations of the substituent position effect using a novel symmetric C70 mono-adduct ([70]NCMA) and a prevalent, high-performance one ([70]PCBM) reveals that we can control the structures of the blend films with conjugated polymers and thereby improve the PSC performances by regioisomer separation. Our approach demonstrates the significance of exploring the best-matching regioisomer of C70 mono-adducts with high-performance conjugated polymers, which would achieve a remarkable progress in PSC devices.
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Affiliation(s)
- Tomokazu Umeyama
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Tetsushi Miyata
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Andreas C Jakowetz
- Cavendish Laboratory , University of Cambridge , J J Thomson Avenue , Cambridge , CB3 0HE , UK .
| | - Sho Shibata
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Kei Kurotobi
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS) , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
| | - Tomohiro Higashino
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Tomoyuki Koganezawa
- Japan Synchrotron Radiation Research Institute , 1-1-1, Kouto, Sayo-cho, Sayo-gun , Hyogo 679-5198 , Japan
| | - Masahiko Tsujimoto
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS) , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
| | - Simon Gélinas
- Cavendish Laboratory , University of Cambridge , J J Thomson Avenue , Cambridge , CB3 0HE , UK .
| | - Wakana Matsuda
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Shu Seki
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan .
| | - Richard H Friend
- Cavendish Laboratory , University of Cambridge , J J Thomson Avenue , Cambridge , CB3 0HE , UK .
| | - Hiroshi Imahori
- Department of Molecular Engineering , Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto , 615-8510 , Japan . .,Institute for Integrated Cell-Material Sciences (WPI-iCeMS) , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
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81
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Herath N, Das S, Zhu J, Kumar R, Chen J, Xiao K, Gu G, Browning JF, Sumpter BG, Ivanov IN, Lauter V. Unraveling the Fundamental Mechanisms of Solvent-Additive-Induced Optimization of Power Conversion Efficiencies in Organic Photovoltaic Devices. ACS APPLIED MATERIALS & INTERFACES 2016; 8:20220-20229. [PMID: 27403964 DOI: 10.1021/acsami.6b04622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The realization of controllable morphologies of bulk heterojunctions (BHJ) in organic photovoltaics (OPVs) is one of the key factors enabling high-efficiency devices. We provide new insights into the fundamental mechanisms essential for the optimization of power conversion efficiencies (PCEs) with additive processing to PBDTTT-CF:PC71BM system. We have studied the underlying mechanisms by monitoring the 3D nanostructural modifications in BHJs and correlated the modifications with the optical analysis and theoretical modeling of charge transport. Our results demonstrate profound effects of diiodooctane (DIO) on morphology and charge transport in the active layers. For small amounts of DIO (<3 vol %), DIO promotes the formation of a well-mixed donor-acceptor compact film and augments charge transfer and PCE. In contrast, for large amounts of DIO (>3 vol %), DIO facilitates a loosely packed mixed morphology with large clusters of PC71BM, leading to deterioration in PCE. Theoretical modeling of charge transport reveals that DIO increases the mobility of electrons and holes (the charge carriers) by affecting the energetic disorder and electric field dependence of the mobility. Our findings show the implications of phase separation and carrier transport pathways to achieve optimal device performances.
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Affiliation(s)
| | - Sanjib Das
- Department of Electrical Engineering and Computer Science, University of Tennessee , Knoxville, Tennessee 37996, United States
| | | | | | | | | | - Gong Gu
- Department of Electrical Engineering and Computer Science, University of Tennessee , Knoxville, Tennessee 37996, United States
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82
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Zarrabi N, Burn PL, Meredith P, Shaw PE. Acceptor and Excitation Density Dependence of the Ultrafast Polaron Absorption Signal in Donor-Acceptor Organic Solar Cell Blends. J Phys Chem Lett 2016; 7:2640-2646. [PMID: 27355877 DOI: 10.1021/acs.jpclett.6b00806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within ∼100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01-50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (<10% by weight), the polaron signal rises gradually over ∼1 ps with most polarons generated after 200 fs, while for higher acceptor concentrations (>10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor-acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor-acceptor interface.
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Affiliation(s)
- Nasim Zarrabi
- Centre for Organic Photonics & Electronics, School of Mathematics & Physics, and School of Chemistry and Molecular Biosciences, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Paul L Burn
- Centre for Organic Photonics & Electronics, School of Mathematics & Physics, and School of Chemistry and Molecular Biosciences, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Paul Meredith
- Centre for Organic Photonics & Electronics, School of Mathematics & Physics, and School of Chemistry and Molecular Biosciences, The University of Queensland , Brisbane, Queensland 4072, Australia
| | - Paul E Shaw
- Centre for Organic Photonics & Electronics, School of Mathematics & Physics, and School of Chemistry and Molecular Biosciences, The University of Queensland , Brisbane, Queensland 4072, Australia
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83
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Vella E, Li H, Grégoire P, Tuladhar SM, Vezie MS, Few S, Bazán CM, Nelson J, Silva-Acuña C, Bittner ER. Ultrafast decoherence dynamics govern photocarrier generation efficiencies in polymer solar cells. Sci Rep 2016; 6:29437. [PMID: 27412119 PMCID: PMC4944175 DOI: 10.1038/srep29437] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 06/17/2016] [Indexed: 11/23/2022] Open
Abstract
All-organic-based photovoltaic solar cells have attracted considerable attention because of their low-cost processing and short energy payback time. In such systems the primary dissociation of an optical excitation into a pair of photocarriers has been recently shown to be extremely rapid and efficient, but the physical reason for this remains unclear. Here, two-dimensional photocurrent excitation spectroscopy, a novel non-linear optical spectroscopy, is used to probe the ultrafast coherent decay of photoexcitations into charge-producing states in a polymer:fullerene based solar cell. The two-dimensional photocurrent spectra are interpreted by introducing a theoretical model for the description of the coupling of the electronic states of the system to an external environment and to the applied laser fields. The experimental data show no cross-peaks in the twodimensional photocurrent spectra, as predicted by the model for coherence times between the exciton and the photocurrent producing states of 20 fs or less.
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Affiliation(s)
- Eleonora Vella
- Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal H3C 3J7, Canada
| | - Hao Li
- Department of Chemistry, University of Houston, Houston, Texas 77204, USA
| | - Pascal Grégoire
- Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal H3C 3J7, Canada
| | - Sachetan M. Tuladhar
- Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Michelle S. Vezie
- Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Sheridan Few
- Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Claudia M. Bazán
- Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal H3C 3J7, Canada
| | - Jenny Nelson
- Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Carlos Silva-Acuña
- Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal H3C 3J7, Canada
- Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Eric R. Bittner
- Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal H3C 3J7, Canada
- Department of Chemistry, University of Houston, Houston, Texas 77204, USA
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84
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Analysis of Triplet Exciton Loss Pathways in PTB7:PC71BM Bulk Heterojunction Solar Cells. Sci Rep 2016; 6:29158. [PMID: 27380928 PMCID: PMC4933975 DOI: 10.1038/srep29158] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/15/2016] [Indexed: 02/03/2023] Open
Abstract
A strategy for increasing the conversion efficiency of organic photovoltaics has been to increase the VOC by tuning the energy levels of donor and acceptor components. However, this opens up a new loss pathway from an interfacial charge transfer state to a triplet exciton (TE) state called electron back transfer (EBT), which is detrimental to device performance. To test this hypothesis, we study triplet formation in the high performing PTB7:PC71BM blend system and determine the impact of the morphology-optimizing additive 1,8-diiodoctane (DIO). Using photoluminescence and spin-sensitive optically detected magnetic resonance (ODMR) measurements at low temperature, we find that TEs form on PC71BM via intersystem crossing from singlet excitons and on PTB7 via EBT mechanism. For DIO blends with smaller fullerene domains, an increased density of PTB7 TEs is observed. The EBT process is found to be significant only at very low temperature. At 300 K, no triplets are detected via ODMR, and electrically detected magnetic resonance on optimized solar cells indicates that TEs are only present on the fullerenes. We conclude that in PTB7:PC71BM devices, TE formation via EBT is impacted by fullerene domain size at low temperature, but at room temperature, EBT does not represent a dominant loss pathway.
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85
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Shen X, Han G, Yi Y. The nature of excited states in dipolar donor/fullerene complexes for organic solar cells: evolution with the donor stack size. Phys Chem Chem Phys 2016; 18:15955-63. [PMID: 27241621 DOI: 10.1039/c6cp02296k] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic delocalization at donor/acceptor (D/A) interfaces can play an important role in photocurrent generation for organic solar cells. Here, we have investigated the nature of local excited and interfacial charge transfer (CT) states in model complexes including one to four anti-parallel stacking dipolar donor (DTDCTB) molecules and one fullerene (C60) molecule by means of density functional theory (DFT) and time-dependent DFT (TDDFT). For all the donor-to-acceptor CT states, despite the number of DTDCTB molecules in the complexes, the hole is mainly localized on a single DTDCTB, and moves farther away from C60 for the energy higher level. However, the highest occupied molecular orbitals (HOMOs) and the excitonic states (EX) including the bright and dark EX are delocalized over the whole donor stacks in the complexes. This implies that the formation of ordered DTDCTB arrangements can substantially shorten the exciton diffusion process and facilitate ultrafast charge generation. Interestingly, owing to strong intermolecular Coulomb attraction, the donor-to-donor CT states are situated below the local excited states, but can approach the donor-to-acceptor CT states, indicating a weak role as charge traps. Our work would be helpful for understanding the electronic delocalization effects in organic solar cells.
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Affiliation(s)
- Xingxing Shen
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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86
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Affiliation(s)
- Koen Vandewal
- Institut für Angewandte Photophysik, Technische Universität Dresden, 01062, Dresden, Germany;
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87
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Hartnett PE, Matte HSSR, Eastham ND, Jackson NE, Wu Y, Chen LX, Ratner MA, Chang RPH, Hersam MC, Wasielewski MR, Marks TJ. Ring-fusion as a perylenediimide dimer design concept for high-performance non-fullerene organic photovoltaic acceptors. Chem Sci 2016; 7:3543-3555. [PMID: 29997846 PMCID: PMC6007210 DOI: 10.1039/c5sc04956c] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/01/2016] [Indexed: 12/12/2022] Open
Abstract
A series of perylenediimide (PDI) dimers are evaluated as acceptors for organic photovoltaic (OPV) cells. The materials are characterized using a wide variety of physical and computational techniques. These dimers are first linked at the bay position of each PDI molecule via an aromatic spacer; subsequent photocyclization affords ring-fused dimers. Thus, photocyclization of the thiophene-linked dimer 2,5-bis-[N,N'-bis-perylenediimide-1-yl]-thiophene (T1) affords the twisted acceptor [2,3-b:2',3'-d]-bis-[N,N'-bis-perylenediimide-1,12-yl]-thiophene (T2), while photocyclization of the thienothiophene-linked dimer, 2,5-bis-[N,N'-bis-perylenediimide-1-yl]-thienothiophene (TT1) affords the planar acceptor [2,3-b:2',3'-d]-bis-[N,N'-bis-perylenediimide-1,12-yl]-thienothiophene (TT2). Furthermore, a dimer linked by a phenylene group, 1,4-bis-[N,N'-bis-perylenediimide-1-yl]-benzene (Ph1), can be selectively photocyclized to form either the twisted dimer, [1,2:3,4]-bis-[N,N'-bis-perylenediimide-1,12-yl]-benzene (Ph1a) or the planar dimer [1,2:4,5]-bis-[N,N'-bis-perylenediimide-1,12-yl]-benzene (Ph2b). Ring-fusion results in increased electronic coupling between the PDI units, and increased space-charge limited thin film electron mobility. While charge transport is efficient in bulk-heterojunction blends of each dimer with the polymeric donor PBDTT-FTTE, in the case of the twisted dimers ring fusion leads to a significant decrease in geminate recombination, hence increased OPV photocurrent density and power conversion efficiency. This effect is not observed in planar dimers where ring fusion leads to increased crystallinity and excimer formation, decreased photocurrent density, and decreased power conversion efficiency. These results argue that ring fusion is an effective approach to increasing OPV bulk-heterojunction charge carrier generation efficiency in PDI dimers as long as they remain relatively amorphous, thereby suppressing excimer formation and coulombically trapped charge transfer states.
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Affiliation(s)
- Patrick E Hartnett
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - H S S Ramakrishna Matte
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; .,Department of Materials Science and Engineering and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA
| | - Nicholas D Eastham
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Nicholas E Jackson
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Yilei Wu
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Lin X Chen
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Mark A Ratner
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Robert P H Chang
- Department of Materials Science and Engineering and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA
| | - Mark C Hersam
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; .,Department of Materials Science and Engineering and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA
| | - Michael R Wasielewski
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ;
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; .,Department of Materials Science and Engineering and the Materials Research Center , The Argonne-Northwestern Solar Energy Research Center , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA
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88
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D'Avino G, Muccioli L, Olivier Y, Beljonne D. Charge Separation and Recombination at Polymer-Fullerene Heterojunctions: Delocalization and Hybridization Effects. J Phys Chem Lett 2016; 7:536-40. [PMID: 26785294 DOI: 10.1021/acs.jpclett.5b02680] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We address charge separation and recombination in polymer/fullerene solar cells with a multiscale modeling built from accurate atomistic inputs and accounting for disorder, interface electrostatics and genuine quantum effects on equal footings. Our results show that bound localized charge transfer states at the interface coexist with a large majority of thermally accessible delocalized space-separated states that can be also reached by direct photoexcitation, thanks to their strong hybridization with singlet polymer excitons. These findings reconcile the recent experimental reports of ultrafast exciton separation ("hot" process) with the evidence that high quantum yields do not require excess electronic or vibrational energy ("cold" process), and show that delocalization, by shifting the density of charge transfer states toward larger effective electron-hole radii, may reduce energy losses through charge recombination.
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Affiliation(s)
- Gabriele D'Avino
- Laboratory for Chemistry of Novel Materials, University of Mons , 7000 Mons, Belgium
| | - Luca Muccioli
- Laboratoire de Chimie des Polymères Organiques, UMR 5629, University of Bordeaux , 33607 Pessac, France
| | - Yoann Olivier
- Laboratory for Chemistry of Novel Materials, University of Mons , 7000 Mons, Belgium
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons , 7000 Mons, Belgium
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89
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Bakulin AA, Silva C, Vella E. Ultrafast Spectroscopy with Photocurrent Detection: Watching Excitonic Optoelectronic Systems at Work. J Phys Chem Lett 2016; 7:250-8. [PMID: 26711855 PMCID: PMC4819534 DOI: 10.1021/acs.jpclett.5b01955] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/29/2015] [Indexed: 05/22/2023]
Abstract
While ultrafast spectroscopy with photocurrent detection was almost unknown before 2012, in the last 3 years, a number of research groups from different fields have independently developed ultrafast electric probe approaches and reported promising pilot studies. Here, we discuss these recent advances and provide our perspective on how photocurrent detection successfully overcomes many limitations of all-optical methods, which makes it a technique of choice when device photophysics is concerned. We also highlight compelling existing problems and research questions and suggest ways for further development, outlining the potential breakthroughs to be expected in the near future using photocurrent ultrafast optical probes.
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Affiliation(s)
- Artem A. Bakulin
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Carlos Silva
- Département de physique & Regroupement
québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Eleonora Vella
- Département de physique & Regroupement
québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
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90
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Hwang YJ, Li H, Courtright BAE, Subramaniyan S, Jenekhe SA. Nonfullerene Polymer Solar Cells with 8.5% Efficiency Enabled by a New Highly Twisted Electron Acceptor Dimer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:124-131. [PMID: 26513532 DOI: 10.1002/adma.201503801] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/16/2015] [Indexed: 06/05/2023]
Abstract
Fullerene-free and processing additive-free 8.5% efficient polymer solar cells are achieved by using a new 3,4-ethylenedioxythiophene-linked arylene diimide dimer with a 76° twist angle. The devices combine high (78-83%) external quantum efficiency with high (0.91-0.95 V) photovoltages and thus have relatively low optical bandgap energy loss.
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Affiliation(s)
- Ye-Jin Hwang
- Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, 98195-1750, USA
| | - Haiyan Li
- Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, 98195-1750, USA
| | - Brett A E Courtright
- Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, 98195-1750, USA
| | - Selvam Subramaniyan
- Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, 98195-1750, USA
| | - Samson A Jenekhe
- Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, 98195-1750, USA
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91
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Zhang C, Zhang J, Zeng W, Zheng N, Li W, Gao W, Yu G, Yang C. Benzobisthiadiazole-alt-bithiazole copolymers with deep HOMO levels for good-performance field-effect transistors with air stability and a high on/off ratio. Polym Chem 2016. [DOI: 10.1039/c6py00212a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two benzobisthiadiazole-alt-bithiazole copolymers were designed and synthesized, and the resulting transistors achieved high performance with air stability and a high on/off ratio.
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Affiliation(s)
- Chen Zhang
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials
- Department of Chemistry
- Wuhan University
- Wuhan
| | - Ji Zhang
- Beijing National Laboratory for Molecular Sciences
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing
- People's Republic of China
| | - Weixuan Zeng
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials
- Department of Chemistry
- Wuhan University
- Wuhan
| | - Naihang Zheng
- Beijing National Laboratory for Molecular Sciences
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing
- People's Republic of China
| | - Wei Li
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials
- Department of Chemistry
- Wuhan University
- Wuhan
| | - Wei Gao
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials
- Department of Chemistry
- Wuhan University
- Wuhan
| | - Gui Yu
- Beijing National Laboratory for Molecular Sciences
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing
- People's Republic of China
| | - Chuluo Yang
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials
- Department of Chemistry
- Wuhan University
- Wuhan
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92
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Li G, Govind N, Ratner MA, Cramer CJ, Gagliardi L. Influence of Coherent Tunneling and Incoherent Hopping on the Charge Transfer Mechanism in Linear Donor-Bridge-Acceptor Systems. J Phys Chem Lett 2015; 6:4889-4897. [PMID: 26554424 DOI: 10.1021/acs.jpclett.5b02154] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The mechanism of charge transfer has been observed to change from tunneling to hopping with increasing numbers of DNA base pairs in polynucleotides and with the length of molecular wires. The aim of this paper is to investigate this transition by examining the population dynamics using a tight-binding Hamiltonian with model parameters to describe a linear donor-bridge-acceptor (D-B-A) system. The model includes a primary vibration and an electron-vibration coupling at each site. A further coupling of the primary vibration with a secondary phonon bath allows the system to dissipate energy to the environment and reach a steady state. We apply the quantum master equation (QME) approach, based on second-order perturbation theory in a quantum dissipative system, to examine the dynamical processes involved in charge-transfer and follow the population transfer rate at the acceptor, ka, to shed light on the transition from tunneling to hopping. With a small tunneling parameter, V, the on-site population tends to localize and form polarons, and the hopping mechanism dominates the transfer process. With increasing V, the population tends to be delocalized and the tunneling mechanism dominates. The competition between incoherent hopping and coherent tunneling governs the mechanism of charge transfer. By varying V and the total number of sites, we also examine the onset of the transition from tunneling to hopping with increasing length.
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Affiliation(s)
- Guangqi Li
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Niranjan Govind
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Mark A Ratner
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Christopher J Cramer
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Laura Gagliardi
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
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93
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de Gier HD, Jahani F, Broer R, Hummelen JC, Havenith RWA. Promising Strategy To Improve Charge Separation in Organic Photovoltaics: Installing Permanent Dipoles in PCBM Analogues. J Phys Chem A 2015; 120:4664-71. [PMID: 26478954 DOI: 10.1021/acs.jpca.5b09279] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multidisciplinary approach involving organic synthesis and theoretical chemistry was applied to investigate a promising strategy to improve charge separation in organic photovoltaics: installing permanent dipoles in fullerene derivatives. First, a PCBM analogue with a permanent dipole in the side chain (PCBDN) and its reference analogue without a permanent dipole (PCBBz) were successfully synthesized and characterized. Second, a multiscale modeling approach was applied to investigate if a PCBDN environment around a central donor-acceptor complex indeed facilitates charge separation. Alignment of the embedding dipoles in response to charges present on the central donor-acceptor complex enhances charge separation. The good correspondence between experimentally and theoretically determined electronic and optical properties of PCBDN, PCBBz, and PCBM indicates that the theoretical analysis of the embedding effects of these molecules gives a reliable expectation for their influence on the charge separation process at a microscopic scale in a real device. This work suggests the following strategies to improve charge separation in organic photovoltaics: installing permanent dipoles in PCBM analogues and tuning the concentration of these molecules in an organic donor/acceptor blend.
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Affiliation(s)
- Hilde D de Gier
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Fatemeh Jahani
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ria Broer
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Jan C Hummelen
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Remco W A Havenith
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Ghent Quantum Chemistry Group, Department of Inorganic and Physical Chemistry, Ghent University , Krijgslaan 281 (S3), B-9000 Gent, Belgium
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94
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Zhong Y, Trinh MT, Chen R, Purdum GE, Khlyabich PP, Sezen M, Oh S, Zhu H, Fowler B, Zhang B, Wang W, Nam CY, Sfeir MY, Black CT, Steigerwald ML, Loo YL, Ng F, Zhu XY, Nuckolls C. Molecular helices as electron acceptors in high-performance bulk heterojunction solar cells. Nat Commun 2015; 6:8242. [PMID: 26382113 PMCID: PMC4595599 DOI: 10.1038/ncomms9242] [Citation(s) in RCA: 493] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/29/2015] [Indexed: 12/25/2022] Open
Abstract
Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometres in diameter for efficient exciton separation and charge transport. This study describes a new motif for designing highly efficient acceptors for organic solar cells.
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Affiliation(s)
- Yu Zhong
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - M Tuan Trinh
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Rongsheng Chen
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA.,School of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081, China
| | - Geoffrey E Purdum
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Petr P Khlyabich
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Melda Sezen
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Seokjoon Oh
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Haiming Zhu
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Brandon Fowler
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Boyuan Zhang
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Wei Wang
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Chang-Yong Nam
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA
| | - Charles T Black
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, New York 11973, USA
| | - Michael L Steigerwald
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Yueh-Lin Loo
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Fay Ng
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, 3000 Broadway, Havemeyer Hall, MC3130, New York, New York 10027, USA
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95
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Lee Y, Gomez ED. Challenges and Opportunities in the Development of Conjugated Block Copolymers for Photovoltaics. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00112] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Youngmin Lee
- Department of Chemical Engineering and ‡Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Enrique D. Gomez
- Department of Chemical Engineering and ‡Materials Research
Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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96
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Monahan NR, Williams KW, Kumar B, Nuckolls C, Zhu XY. Direct Observation of Entropy-Driven Electron-Hole Pair Separation at an Organic Semiconductor Interface. PHYSICAL REVIEW LETTERS 2015. [PMID: 26196998 DOI: 10.1103/physrevlett.114.247003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
How an electron-hole pair escapes the Coulomb potential at a donor-acceptor interface has been a key issue in organic photovoltaic research. Recent evidence suggests that long-distance charge separation can occur on ultrafast time scales, yet the underlying mechanism remains unclear. Here we use charge transfer excitons (CTEs) across an organic semiconductor-vacuum interface as a model and show that nascent hot CTEs can spontaneously climb up the Coulomb potential within 100 fs. This process is driven by entropic gain due to the rapid rise in density of states with increasing electron-hole separation. In contrast, the lowest CTE cannot delocalize, but undergoes self-trapping and recombination.
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Affiliation(s)
- Nicholas R Monahan
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Kristopher W Williams
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Bharat Kumar
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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97
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Zhu X, Monahan NR, Gong Z, Zhu H, Williams KW, Nelson CA. Charge Transfer Excitons at van der Waals Interfaces. J Am Chem Soc 2015; 137:8313-20. [DOI: 10.1021/jacs.5b03141] [Citation(s) in RCA: 216] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Nicholas R. Monahan
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Zizhou Gong
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Haiming Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | | | - Cory A. Nelson
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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98
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Bartynski AN, Gruber M, Das S, Rangan S, Mollinger S, Trinh C, Bradforth SE, Vandewal K, Salleo A, Bartynski RA, Bruetting W, Thompson ME. Symmetry-Breaking Charge Transfer in a Zinc Chlorodipyrrin Acceptor for High Open Circuit Voltage Organic Photovoltaics. J Am Chem Soc 2015; 137:5397-405. [DOI: 10.1021/jacs.5b00146] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Mark Gruber
- Institute
for Physics, Augsburg University, 86135 Augsburg, Germany
| | | | - Sylvie Rangan
- Department
of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Sonya Mollinger
- Department
of Materials Science and Engineering, Stanford University, Palo Alto, California 94305, United States
| | | | | | - Koen Vandewal
- Department
of Materials Science and Engineering, Stanford University, Palo Alto, California 94305, United States
| | - Alberto Salleo
- Department
of Materials Science and Engineering, Stanford University, Palo Alto, California 94305, United States
| | - Robert A. Bartynski
- Department
of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
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99
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Liu SY, Wu CH, Li CZ, Liu SQ, Wei KH, Chen HZ, Jen AKY. A Tetraperylene Diimides Based 3D Nonfullerene Acceptor for Efficient Organic Photovoltaics. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2015; 2:1500014. [PMID: 27980932 PMCID: PMC5115352 DOI: 10.1002/advs.201500014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 02/03/2015] [Indexed: 05/29/2023]
Abstract
A nonfullerene acceptor based on a 3D tetraperylene diimide is developed for bulk heterojunction organic photovoltaics. The disruption of perylene diimide planarity with a 3D framework suppresses the self-aggregation of perylene diimide and inhibits excimer formation. From planar monoperylene diimide to 3D tetraperylene diimide, a significant improvement of power conversion efficiency from 0.63% to 3.54% can be achieved.
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Affiliation(s)
- Shi-Yong Liu
- Department of Materials Science and Engineering University of Washington Box 352120 Seattle WA 98195 USA; Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 P.R. China; Department of Pharmacy and Chemistry Taizhou University Taizhou 317000 P.R. China
| | - Chen-Hao Wu
- Department of Materials Science and Engineering University of Washington Box 352120 Seattle WA 98195 USA; Department of Chemical Engineering National Cheng Kung University Tainan 70101 Taiwan
| | - Chang-Zhi Li
- Department of Materials Science and Engineering University of Washington Box 352120 Seattle WA 98195 USA
| | - Sheng-Qiang Liu
- Department of Materials Science and Engineering University of Washington Box 352120 Seattle WA 98195 USA
| | - Kung-Hwa Wei
- Department of Materials Science and Engineering National Chiao Tung University 300 Hsinchu Taiwan
| | - Hong-Zheng Chen
- Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 P.R. China
| | - Alex K-Y Jen
- Department of Materials Science and Engineering University of Washington Box 352120 Seattle WA 98195 USA; Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 P.R. China
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100
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Gao F, Tress W, Wang J, Inganäs O. Temperature dependence of charge carrier generation in organic photovoltaics. PHYSICAL REVIEW LETTERS 2015; 114:128701. [PMID: 25860774 DOI: 10.1103/physrevlett.114.128701] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Indexed: 06/04/2023]
Abstract
The charge generation mechanism in organic photovoltaics is a fundamental yet heavily debated issue. All the generated charges recombine at the open-circuit voltage (V_{OC}), so that investigation of recombined charges at V_{OC} provides a unique approach to understanding charge generation. At low temperatures, we observe a decrease of V_{OC}, which is attributed to reduced charge separation. Comparison between benchmark polymer:fullerene and polymer:polymer blends highlights the critical role of charge delocalization in charge separation and emphasizes the importance of entropy in charge generation.
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Affiliation(s)
- Feng Gao
- Biomolecular and Organic Electronics, IFM, Linköping University, Linköping 58183, Sweden
- Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Wolfgang Tress
- Biomolecular and Organic Electronics, IFM, Linköping University, Linköping 58183, Sweden
| | - Jianpu Wang
- Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), National Synergistic Innovation Centre for Advanced Materials (SICAM), Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Olle Inganäs
- Biomolecular and Organic Electronics, IFM, Linköping University, Linköping 58183, Sweden
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