1
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Wang Y, Zheng Z, Wang J, Bi P, Chen Z, Ren J, An C, Zhang S, Hou J. Organic laser power converter for efficient wireless micro power transfer. Nat Commun 2023; 14:5511. [PMID: 37679350 PMCID: PMC10484967 DOI: 10.1038/s41467-023-41270-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023] Open
Abstract
Wireless power transfer with collimated power transmission and efficient conversion provides an alternative charging mode for off-grid and portable micro-power electronics. However, charging micro-power electronics with low photon flux can be challenging for current laser power converters. Here we show laser power converters with organic photovoltaic cells with good performance for application in laser wireless power transfer. The laser selection strategy is established and the upper limit of efficiency is proposed. The organic laser power converters exhibit a 36.2% efficiency at a 660 nm laser with a photon flux of 9.5 mW cm-2 and achieve wireless micro power transfer with an output of 0.5 W on a 2 meter scale. This work shows the good performance of organic photovoltaic cells in constructing organic laser power converters and provides a potential solution for the wireless power transfer of micro-power electronics.
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Affiliation(s)
- Yafei Wang
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhong Zheng
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Chemistry and Biology Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Jianqiu Wang
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Pengqing Bi
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhihao Chen
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Junzhen Ren
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Cunbin An
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shaoqing Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemistry and Biology Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Jianhui Hou
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- School of Chemistry and Biology Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
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2
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Andermann AM, Rego LGC. Quantum Mechanical Assessment of Optimal Photovoltaic Conditions in Organic Solar Cells. J Phys Chem Lett 2022; 13:11001-11007. [PMID: 36404620 DOI: 10.1021/acs.jpclett.2c02622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Recombination losses contribute to reducing JSC, VOC, and the fill factor of organic solar cells. Recent advances in non-fullerene organic photovoltaics have shown, nonetheless, that efficient charge generation can occur under small energetic driving forces (ΔEDA) and low recombination losses. To shed light on this issue, we set up a coarse-grained open quantum mechanical model for investigating the charge generation dynamics subject to various energy loss mechanisms. The influences of energetic driving force, Coulomb interaction, vibrational disorder, geminate recombination, temperature, and external bias are included in the analysis of the optimal photovoltaic conditions for charge carrier generation. The assessment reveals that the overall energy losses are not only minimized when ΔEDA approaches the effective reorganization energy at the interface but also become insensitive to temperature and electric field variations. It is also observed that a moderate reverse bias reduces geminate recombination losses significantly at vanishing driving forces, where the charge generation is strongly affected by temperature.
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Affiliation(s)
- Artur M Andermann
- Department of Physics, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil
| | - Luis G C Rego
- Department of Physics, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina, Brazil
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3
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Pitchaiya S, Eswaramoorthy N, Madurai Ramakrishnan V, Natarajan M, Velauthapillai D. Bio-Inspired Graphitic Carbon-Based Large-Area (10 × 10 cm 2) Perovskite Solar Cells: Stability Assessments under Indoor, Outdoor, and Water-Soaked Conditions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:43050-43066. [PMID: 36099647 DOI: 10.1021/acsami.2c02463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In the emerging photovoltaic (PV) technologies, the golden triangle rule includes higher efficiency, longevity (or stability), and low cost, which are the foremost criteria for the root of commercial feasibility. Accordingly, a unique low-cost, ecofriendly, all-solution-processed, "bio-inspired" graphitic carbon (extracted from the most invasive plant species of Eichhornia crassipes: listed as one of the 100 most dangerous species by the International Union for Conservation of Nature) and a mixed halide perovskite interface-engineered, unique single-cell large-scale (10 × 10 sq.cm with an active area of 88 cm2) carbon-based perovskite solar cell (C-PSC) are demonstrated for the first time, delivering a maximum PCE of 6.32%. Notable performance was observed under low light performance for the interface-engineered champion device fabricated using the layer-to-layer approach, which, even when tested under fluorescent room light condition (at 200 lux of about ∼0.1 SUN illumination), exhibited a significant PCE. In terms of addressing the stability issues in the fabricated PSC devices, the present work has adopted a two-step strategy: the instability toward the extrinsic factors is addressed by encapsulation, and the subsequent intrinsic instability issue is also addressed through interfacial engineering. Surprisingly, when tested under various stability conditions (STC) such as ambient air, light (continuous 1 SUN, under room light illumination (0.1 SUN) and direct sunlight), severe damp up to a depth of ∼25 mm water (cold (∼15 °C) and hot (∼65 °C)), acidic pH (∼5), and alkaline pH (∼11)) conditions, the fabricated large-scale carbon-based perovskite solar cells (C-LSPSCs) retained unexpected long-term stability in their performance for over 50 days. As to appraise the performance superiority of the fabricated C-LSPSC devices under various aforesaid testing conditions, a working model of a mini-fan has been practically powered and demonstrated.
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Affiliation(s)
- Selvakumar Pitchaiya
- Faculty of Engineering and Science, Western Norway University of Applied Sciences, 5063 Bergen, Norway
- Department of Physics, Coimbatore Institute of Technology, Coimbatore, Tamil Nadu 641 014, India
| | - Nandhakumar Eswaramoorthy
- School of Mechanical Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu 632 014, India
| | - Venkatraman Madurai Ramakrishnan
- Department of Physics, Coimbatore Institute of Technology, Coimbatore, Tamil Nadu 641 014, India
- Department of Physics, Dr. N.G.P. Arts and Science College, Coimbatore, Tamil Nadu 641 048, India
| | | | - Dhayalan Velauthapillai
- Faculty of Engineering and Science, Western Norway University of Applied Sciences, 5063 Bergen, Norway
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4
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Liu YX, Wang L, Zhou K, Wu HB, Zhou XB, Ma ZF, Guo SW, Ma W. Subtle Alignment of Organic Semiconductors at the Donor/Acceptor Heterojunction Facilitates the Photoelectric Conversion Process. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2759-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Yan Y, Zhang Y, Memon WA, Wang M, Zhang X, Wei Z. The role of entropy gains in the exciton separation in organic solar cells. Macromol Rapid Commun 2022; 43:e2100903. [PMID: 35338684 DOI: 10.1002/marc.202100903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/16/2022] [Indexed: 11/06/2022]
Abstract
In organic solar cell (OSC), the lower dielectric constant of organic semiconductor material induces a strong Coulomb attraction between electron-hole pairs, which leads to a low exciton separation efficiency, especially the charge transfer (CT) state. The CT state formed at the electron-donor (D) and electron-acceptor (A) interface is regarded as an unfavorable property of organic photovoltaic devices. Since the OSC works in a nonzero temperature condition, the entropy effect would be one of the main reasons to overcome the Coulomb energy barrier and must be taken into account. In this review, we review the present understanding of the entropy-driven charge separation and describe how factors such as the dimensionality of the organic semiconductor, energy disorder effect, the morphology of the active layer, and the nonequilibrium effect affect the entropy contribution in compensating the Coulomb dissociation barrier for CT exciton separation and charge generation process. We focus on the investigation of the entropy effect on exciton dissociation mechanism from both theoretical and experimental aspects, which provides pathways for understanding the underlying mechanisms of exciton separation and further enhancing the efficiency of OSCs. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Yangjun Yan
- School of Science, Beijing Jiaotong University, Beijing, 100044, China.,CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Yajie Zhang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Waqar Ali Memon
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Mengni Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Xinghua Zhang
- School of Science, Beijing Jiaotong University, Beijing, 100044, China
| | - Zhixiang Wei
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
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6
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Andermann AM, Rego LGC. Energetics of the charge generation in organic donor-acceptor interfaces. J Chem Phys 2022; 156:024104. [PMID: 35032994 DOI: 10.1063/5.0076611] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Non-fullerene acceptor materials have posed new paradigms for the design of organic solar cells , whereby efficient carrier generation is obtained with small driving forces, in order to maximize the open-circuit voltage (VOC). In this paper, we use a coarse-grained mixed quantum-classical method, which combines Ehrenfest and Redfield theories, to shed light on the charge generation process in small energy offset interfaces. We have investigated the influence of the energetic driving force as well as the vibronic effects on the charge generation and photovoltaic energy conversion. By analyzing the effects of the Holstein and Peierls vibrational couplings, we find that vibrational couplings produce an overall effect of improving the charge generation. However, the two vibronic mechanisms play different roles: the Holstein relaxation mechanism decreases the charge generation, whereas the Peierls mechanism always assists the charge generation. Moreover, by examining the electron-hole binding energy as a function of time, we evince two distinct regimes for the charge separation: the temperature independent excitonic spread on a sub-100 fs timescale and the complete dissociation of the charge-transfer state that occurs on the timescale of tens to hundreds of picoseconds, depending on the temperature. The quantum dynamics of the system exhibits the three regimes of the Marcus electron transfer kinetics as the energy offset of the interface is varied.
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Affiliation(s)
- Artur M Andermann
- Department of Physics, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil
| | - Luis G C Rego
- Department of Physics, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil
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7
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Carr JM, Allen TG, Larson BW, Davydenko IG, Dasari RR, Barlow S, Marder SR, Reid OG, Rumbles G. Short and long-range electron transfer compete to determine free-charge yield in organic semiconductors. MATERIALS HORIZONS 2022; 9:312-324. [PMID: 34787147 DOI: 10.1039/d1mh01331a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding how Frenkel excitons efficiently split to form free-charges in low-dielectric constant organic semiconductors has proven challenging, with many different models proposed in recent years to explain this phenomenon. Here, we present evidence that a simple model invoking a modest amount of charge delocalization, a sum over the available microstates, and the Marcus rate constant for electron transfer can explain many seemingly contradictory phenomena reported in the literature. We use an electron-accepting fullerene host matrix dilutely sensitized with a series of electron donor molecules to test this hypothesis. The donor series enables us to tune the driving force for photoinduced electron transfer over a range of 0.7 eV, mapping out normal, optimal, and inverted regimes for free-charge generation efficiency, as measured by time-resolved microwave conductivity. However, the photoluminescence of the donor is rapidly quenched as the driving force increases, with no evidence for inverted behavior, nor the linear relationship between photoluminescence quenching and charge-generation efficiency one would expect in the absence of additional competing loss pathways. This behavior is self-consistently explained by competitive formation of bound charge-transfer states and long-range or delocalized free-charge states, where both rate constants are described by the Marcus rate equation. Moreover, the model predicts a suppression of the inverted regime for high-concentration blends and efficient ultrafast free-charge generation, providing a mechanistic explanation for why Marcus-inverted-behavior is rarely observed in device studies.
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Affiliation(s)
- Joshua M Carr
- University of Colorado Boulder, Materials Science & Engineering Program, Boulder, CO, 80303, USA
| | - Taylor G Allen
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Bryon W Larson
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
| | - Iryna G Davydenko
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Raghunath R Dasari
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
| | - Stephen Barlow
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Seth R Marder
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA, 30332, USA
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemical and Biological Engineering, Boulder, CO, 80303, USA
| | - Obadiah G Reid
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
| | - Garry Rumbles
- National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, CO, 80401, USA.
- University of Colorado Boulder, Renewable and Sustainable Energy Institute, Boulder, CO, 80303, USA
- University of Colorado Boulder, Department of Chemistry, Boulder, CO, 80303, USA
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8
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Mohammadi M, Gholipour S, Malekshahi Byranvand M, Abdi Y, Taghavinia N, Saliba M. Encapsulation Strategies for Highly Stable Perovskite Solar Cells under Severe Stress Testing: Damp Heat, Freezing, and Outdoor Illumination Conditions. ACS APPLIED MATERIALS & INTERFACES 2021; 13:45455-45464. [PMID: 34528780 DOI: 10.1021/acsami.1c11628] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A key direction toward managing extrinsic instabilities in perovskite solar cells (PSCs) is encapsulation. Thus, a suitable sealing layer is required for an efficient device encapsulation, preventing moisture and oxygen ingression into the perovskite layer. In this work, a solution-based, low-cost, and commercially available bilayer structure of poly(methyl methacrylate)/styrene-butadiene (PMMA/SB) is investigated for PSCs encapsulation. Encapsulated devices retained 80% of the initial power conversion efficiency (PCE) at 85 °C temperature and 85% relative humidity after 100 h, while reference devices without SB (only PMMA) suffer from rapid and intense degradation after only 2 h, under the same condition. In addition, encapsulated devices retained 95% of the initial PCE under -15 °C freezing temperature after 6 h and retained ∼80% of the initial PCE after immersion in HCl (37%) for 90 min. Moreover, applying an additional aluminum metal sheet on the PMMA/SB protective bilayer leads to the improvement of device stability up to 500 h under outdoor illumination, retaining almost 90% of the initial PCE. Considering the urge to develop reliable, scalable, and simple encapsulation for future large-area PSCs, this work establishes solution-based bilayer encapsulation, which is applicable for flexible solar modules as well as other optoelectronic devices such as light-emitting devices and photodetectors.improvement of device stability up to 500 h under outdoor illumination, retaining almost 90% of the initial PCE. Considering the urge to develop reliable, scalable, and simple encapsulation for future large-area PSCs, this work establishes solution-based bilayer encapsulation, which is applicable for flexible solar modules as well as other optoelectronic devices such as light-emitting devices and photodetectors.
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Affiliation(s)
- Mahdi Mohammadi
- Nanoparticles and Coating Lab, Department of Physics, Sharif University of Technology, Tehran 14588, Iran
| | - Somayeh Gholipour
- Nanophysics Research Laboratory, Department of Physics, University of Tehran, Tehran 14395-547, Iran
| | - Mahdi Malekshahi Byranvand
- Institute for Photovoltaics (ipv), University of Stuttgart, Pfaffenwaldring 47, Stuttgart D-70569, Germany
- Helmholtz Young Investigator Group, IEK5-Photoevoltaik, Forschungszentrum, Jülich 52425, Germany
| | - Yaser Abdi
- Nanophysics Research Laboratory, Department of Physics, University of Tehran, Tehran 14395-547, Iran
| | - Nima Taghavinia
- Nanoparticles and Coating Lab, Department of Physics, Sharif University of Technology, Tehran 14588, Iran
| | - Michael Saliba
- Institute for Photovoltaics (ipv), University of Stuttgart, Pfaffenwaldring 47, Stuttgart D-70569, Germany
- Helmholtz Young Investigator Group, IEK5-Photoevoltaik, Forschungszentrum, Jülich 52425, Germany
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9
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Kaiser W, Janković V, Vukmirović N, Gagliardi A. Nonequilibrium Thermodynamics of Charge Separation in Organic Solar Cells. J Phys Chem Lett 2021; 12:6389-6397. [PMID: 34232672 DOI: 10.1021/acs.jpclett.1c01817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This work presents a novel theoretical description of the nonequilibrium thermodynamics of charge separation in organic solar cells (OSCs). Using stochastic thermodynamics, we take realistic state populations derived from the phonon-assisted dynamics of electron-hole pairs within photoexcited organic bilayers to connect the kinetics with the free energy profile of charge separation. Hereby, we quantify for the first time the difference between nonequilibrium and equilibrium free energy profile. We analyze the impact of energetic disorder and delocalization on free energy, average energy, and entropy. For a high disorder, the free energy profile is well-described as equilibrated. We observe significant deviations from equilibrium for delocalized electron-hole pairs at a small disorder, implying that charge separation in efficient OSCs proceeds via a cold but nonequilibrated pathway. Both a large Gibbs entropy and large initial electron-hole distance provide an efficient charge separation, while a decrease in the free energy barrier does not necessarily enhance charge separation.
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Affiliation(s)
- Waldemar Kaiser
- Department of Electrical and Computer Engineering, Technical University of Munich, Karlstraße 45, 80333 Munich, Germany
| | - Veljko Janković
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Nenad Vukmirović
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Alessio Gagliardi
- Department of Electrical and Computer Engineering, Technical University of Munich, Karlstraße 45, 80333 Munich, Germany
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10
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Improving organic photovoltaic cells by forcing electrode work function well beyond onset of Ohmic transition. Nat Commun 2021; 12:2250. [PMID: 33854070 PMCID: PMC8047006 DOI: 10.1038/s41467-021-22358-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 02/23/2021] [Indexed: 12/03/2022] Open
Abstract
As electrode work function rises or falls sufficiently, the organic semiconductor/electrode contact reaches Fermi-level pinning, and then, few tenths of an electron-volt later, Ohmic transition. For organic solar cells, the resultant flattening of open-circuit voltage (Voc) and fill factor (FF) leads to a ‘plateau’ that maximizes power conversion efficiency (PCE). Here, we demonstrate this plateau in fact tilts slightly upwards. Thus, further driving of the electrode work function can continue to improve Voc and FF, albeit slowly. The first effect arises from the coercion of Fermi level up the semiconductor density-of-states in the case of ‘soft’ Fermi pinning, raising cell built-in potential. The second effect arises from the contact-induced enhancement of majority-carrier mobility. We exemplify these using PBDTTPD:PCBM solar cells, where PBDTTPD is a prototypal face-stacked semiconductor, and where work function of the hole collection layer is systematically ‘tuned’ from onset of Fermi-level pinning, through Ohmic transition, and well into the Ohmic regime. Both open-circuit voltage and fill factor of organic solar cells are affected by the metal-organic semiconductor interface. Here, the authors demonstrate that the voltage can continue to rise when the Fermi level is forced up to the semiconductor density-of-states tail.
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11
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Limbu S, Park KB, Wu J, Cha H, Yun S, Lim SJ, Yan H, Luke J, Ryu G, Heo CJ, Kim S, Jin YW, Durrant JR, Kim JS. Identifying the Molecular Origins of High-Performance in Organic Photodetectors Based on Highly Intermixed Bulk Heterojunction Blends. ACS NANO 2021; 15:1217-1228. [PMID: 33332092 DOI: 10.1021/acsnano.0c08287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A bulk-heterojunction (BHJ) structure of organic semiconductor blend is widely used in photon-to-electron converting devices such as organic photodetectors (OPD) and photovoltaics (OPV). However, the impact of the molecular structure on the interfacial electronic states and optoelectronic properties of the constituent organic semiconductors is still unclear, limiting further development of these devices for commercialization. Herein, the critical role of donor molecular structure on OPD performance is identified in highly intermixed BHJ blends containing a small-molecule donor and C60 acceptor. Blending introduces a twisted structure in the donor molecule and a strong coupling between donor and acceptor molecules. This results in ultrafast exciton separation (<1 ps), producing bound (binding energy ∼135 meV), localized (∼0.9 nm), and highly emissive interfacial charge transfer (CT) states. These interfacial CT states undergo efficient dissociation under an applied electric field, leading to highly efficient OPDs in reverse bias but poor OPVs. Further structural twisting and molecular-scale aggregation of the donor molecules occur in blends upon thermal annealing just above the transition temperature of 150 °C at which donor molecules start to reorganize themselves without any apparent macroscopic phase-segregation. These subtle structural changes lead to significant improvements in charge transport and OPD performance, yielding ultralow dark currents (∼10-10 A cm-2), 2-fold faster charge extraction (in μs), and nearly an order of magnitude increase in effective carrier mobility. Our results provide molecular insights into high-performance OPDs by identifying the role of subtle molecular structural changes on device performance and highlight key differences in the design of BHJ blends for OPD and OPV devices.
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Affiliation(s)
- Saurav Limbu
- Department of Physics and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Kyung-Bae Park
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - Jiaying Wu
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hyojung Cha
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Sungyoung Yun
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - Seon-Jeong Lim
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - Hao Yan
- Department of Physics and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Joel Luke
- Department of Physics and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Gihan Ryu
- Department of Physics and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Chul-Joon Heo
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - Sunghan Kim
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - Yong Wan Jin
- Organic Materials Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do16678, South Korea
| | - James R Durrant
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Ji-Seon Kim
- Department of Physics and Centre for Processable Electronics, Imperial College London, London SW7 2AZ, United Kingdom
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12
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Hinrichsen TF, Chan CCS, Ma C, Paleček D, Gillett A, Chen S, Zou X, Zhang G, Yip HL, Wong KS, Friend RH, Yan H, Rao A, Chow PCY. Long-lived and disorder-free charge transfer states enable endothermic charge separation in efficient non-fullerene organic solar cells. Nat Commun 2020; 11:5617. [PMID: 33154367 PMCID: PMC7645751 DOI: 10.1038/s41467-020-19332-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/28/2020] [Indexed: 11/17/2022] Open
Abstract
Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor–acceptor energy offsets to drive charge separation and overcome the mutual Coulomb attraction between electron and hole. Here, we use time-resolved optical spectroscopy to show that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states that occurs over hundreds of picoseconds at room temperature, three orders of magnitude slower than comparable fullerene-based systems. Upon free electron–hole encounters at later times, both charge-transfer states and emissive excitons are regenerated, thus setting up an equilibrium between excitons, charge-transfer states and free charges. Our results suggest that the formation of long-lived and disorder-free charge-transfer states in these systems enables them to operate closely to quasi-thermodynamic conditions with no requirement for energy offsets to drive interfacial charge separation and achieve suppressed non-radiative recombination. Designing efficient organic solar cells is limited by the energy required to overcome the mutual Coulomb attraction between electron and hole. Here, the authors reveal long-lived and disorder-free charge-transfer states enable efficient endothermic charge separation in non-fullerene systems with marginal energy offset.
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Affiliation(s)
- Ture F Hinrichsen
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Christopher C S Chan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Chao Ma
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - David Paleček
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Alexander Gillett
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Shangshang Chen
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Xinhui Zou
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Guichuan Zhang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Hin-Lap Yip
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Kam Sing Wong
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Richard H Friend
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | - He Yan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China.
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | - Philip C Y Chow
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China. .,Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China.
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13
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Wang R, Zhang C, Li Q, Zhang Z, Wang X, Xiao M. Charge Separation from an Intra-Moiety Intermediate State in the High-Performance PM6:Y6 Organic Photovoltaic Blend. J Am Chem Soc 2020; 142:12751-12759. [DOI: 10.1021/jacs.0c04890] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qian Li
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhiguo Zhang
- College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
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14
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Bian Q, Abdulahi BA, Genene Z, Wang E, Mammo W, Inganäs O. Reduced Nonradiative Voltage Loss in Terpolymer Solar Cells. J Phys Chem Lett 2020; 11:3796-3802. [PMID: 32338006 DOI: 10.1021/acs.jpclett.0c00915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The dissociation of hybrid local exciton and charge transfer excitons (LE-CT) in efficient bulk-heterojunction nonfullerene solar cells contributes to reduced nonradiative photovoltage loss, a mechanism that still remains unclear. Herein we studied the energetic and entropic contribution in the hybrid LE-CT exciton dissociation in devices based on a conjugated terpolymer. Compared with reference devices based on ternary blends, the terpolymer devices demonstrated a significant reduction in the nonradiative photovoltage loss, regardless of the acceptor molecule, be it fullerene or nonfullerene. Fourier transform photocurrent spectroscopy revealed a significant LE-CT character in the terpolymer-based solar cells. Temperature-dependent hole mobility and photovoltage confirm that entropic and energetic effects contribute to the efficient LE-CT dissociation. The energetic disorder value measured in the fullerene- or nonfullerene-based terpolymer devices suggested that this entropic contribution came from the terpolymer, a signature of higher disorder in copolymers with multiple aromatic groups. This gives new insight into the fundamental physics of efficient LE-CT exciton dissociation with smaller nonradiative recombination loss.
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Affiliation(s)
- Qingzhen Bian
- Biomolecular and Organic Electronics, Department of Physics, Chemistry and Biology, Linköping University, Linköping SE-581 83, Sweden
| | - Birhan A Abdulahi
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
- Department of Chemistry, Addis Ababa University, P.O. Box 33658, Addis Ababa, Ethiopia
- Department of Chemistry, Wollo University, P.O. Box 1145, Dessie, Ethiopia
| | - Zewdneh Genene
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
| | - Ergang Wang
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
| | - Wendimagegn Mammo
- Department of Chemistry, Addis Ababa University, P.O. Box 33658, Addis Ababa, Ethiopia
| | - Olle Inganäs
- Biomolecular and Organic Electronics, Department of Physics, Chemistry and Biology, Linköping University, Linköping SE-581 83, Sweden
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15
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Photoconversion Mechanism at the pn-Homojunction Interface in Single Organic Semiconductor. MATERIALS 2020; 13:ma13071727. [PMID: 32272671 PMCID: PMC7178707 DOI: 10.3390/ma13071727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 11/17/2022]
Abstract
Clarifying critical differences in free charge generation and recombination processes between inorganic and organic semiconductors is important for developing efficient organic photoconversion devices such as solar cells (SCs) and photodetector. In this study, we analyzed the dependence of doping concentration on the photoconversion process at the organic pn-homojunction interface in a single organic semiconductor using the temperature dependence of J–V characteristics and energy structure measurements. Even though the organic pn-homojunction SC devices were fabricated using a single host material and the doping technique resembling an inorganic pn-homojunction, the charge generation and recombination mechanisms are similar to that of conventional donor/acceptor (D/A) type organic SCs; that is, the charge separation happens from localized exciton and charge transfer (CT) state being separated by the energy offset between adjacent molecules, and the recombination happens from localized charge carrier at two adjacent molecules. The determining factor for photoconversion processes is the localized nature of charges in organic semiconductors. The results demonstrated that controlling the delocalization of the charges is important to realize efficient organic photoconversion devices.
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16
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Perdigón-Toro L, Zhang H, Markina A, Yuan J, Hosseini SM, Wolff CM, Zuo G, Stolterfoht M, Zou Y, Gao F, Andrienko D, Shoaee S, Neher D. Barrierless Free Charge Generation in the High-Performance PM6:Y6 Bulk Heterojunction Non-Fullerene Solar Cell. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906763. [PMID: 31975446 DOI: 10.1002/adma.201906763] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/19/2019] [Indexed: 05/22/2023]
Abstract
Organic solar cells are currently experiencing a second golden age thanks to the development of novel non-fullerene acceptors (NFAs). Surprisingly, some of these blends exhibit high efficiencies despite a low energy offset at the heterojunction. Herein, free charge generation in the high-performance blend of the donor polymer PM6 with the NFA Y6 is thoroughly investigated as a function of internal field, temperature and excitation energy. Results show that photocurrent generation is essentially barrierless with near-unity efficiency, regardless of excitation energy. Efficient charge separation is maintained over a wide temperature range, down to 100 K, despite the small driving force for charge generation. Studies on a blend with a low concentration of the NFA, measurements of the energetic disorder, and theoretical modeling suggest that CT state dissociation is assisted by the electrostatic interfacial field which for Y6 is large enough to compensate the Coulomb dissociation barrier.
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Affiliation(s)
- Lorena Perdigón-Toro
- Soft Matter Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
- Disordered Semiconductor Optoelectronics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Huotian Zhang
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden
| | - Anastasia Markina
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Jun Yuan
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Seyed Mehrdad Hosseini
- Disordered Semiconductor Optoelectronics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Christian M Wolff
- Soft Matter Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Guangzheng Zuo
- Soft Matter Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Martin Stolterfoht
- Soft Matter Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Yingping Zou
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Feng Gao
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden
| | - Denis Andrienko
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Safa Shoaee
- Disordered Semiconductor Optoelectronics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Dieter Neher
- Soft Matter Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
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17
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Vibronic coherence contributes to photocurrent generation in organic semiconductor heterojunction diodes. Nat Commun 2020; 11:617. [PMID: 32001688 PMCID: PMC6992633 DOI: 10.1038/s41467-020-14476-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 01/09/2020] [Indexed: 11/24/2022] Open
Abstract
Charge separation dynamics after the absorption of a photon is a fundamental process relevant both for photosynthetic reaction centers and artificial solar conversion devices. It has been proposed that quantum coherence plays a role in the formation of charge carriers in organic photovoltaics, but experimental proofs have been lacking. Here we report experimental evidence of coherence in the charge separation process in organic donor/acceptor heterojunctions, in the form of low frequency oscillatory signature in the kinetics of the transient absorption and nonlinear two-dimensional photocurrent spectroscopy. The coherence plays a decisive role in the initial ~200 femtoseconds as we observe distinct experimental signatures of coherent photocurrent generation. This coherent process breaks the energy barrier limitation for charge formation, thus competing with excitation energy transfer. The physics may inspire the design of new photovoltaic materials with high device performance, which explore the quantum effects in the next-generation optoelectronic applications. Although coherent vibrational motion in donor-acceptor blends may contribute to photogeneration generation in organic solar cells (OSCs), proof of a direct correlation is still lacking. Here, the authors report the role of vibrational coherence on photocurrent generation in ternary OSC blends.
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18
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Athanasopoulos S, Bässler H, Köhler A. Disorder vs Delocalization: Which Is More Advantageous for High-Efficiency Organic Solar Cells? J Phys Chem Lett 2019; 10:7107-7112. [PMID: 31661274 DOI: 10.1021/acs.jpclett.9b02866] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate the combined influence of energetic disorder and delocalization on electron-hole charge-transfer state separation efficiency in donor-acceptor organic photovoltaic systems using an analytical hopping model and Monte Carlo calculations, coupled with an effective mass model. Whereas energetic disorder increases the separation yield at intermediate and low electric fields for low-efficiency blends with strongly localized carriers, we find that it reduces dramatically the fill factors and power conversion efficiencies in high-efficiency solar cells that require high carrier delocalization within the conjugated segment and high mobility-lifetime product. We further demonstrate that the initial electron-hole distance and thermalization processes play only a minor role in the separation dynamics.
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Affiliation(s)
- Stavros Athanasopoulos
- Departamento de Física , Universidad Carlos III de Madrid , Avenida Universidad 30 , 28911 Leganés, Madrid , Spain
| | - Heinz Bässler
- Bayreuth Institute of Macromolecular Research (BIMF) and Bavarian Polymer Institute (BPI) , University of Bayreuth , Bayreuth 95440 , Germany
| | - Anna Köhler
- Bayreuth Institute of Macromolecular Research (BIMF) and Bavarian Polymer Institute (BPI) , University of Bayreuth , Bayreuth 95440 , Germany
- Soft Matter Optoelectronics , University of Bayreuth , Bayreuth 95440 , Germany
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19
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Li Y, Sheriff HKM, Liu X, Wang CK, Ding K, Han H, Wong KT, Forrest SR. Vacuum-Deposited Biternary Organic Photovoltaics. J Am Chem Soc 2019; 141:18204-18210. [PMID: 31639297 DOI: 10.1021/jacs.9b09012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - Chun-Kai Wang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | | | - Han Han
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Ken-Tsung Wong
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
- Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan
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20
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Nakano K, Chen Y, Xiao B, Han W, Huang J, Yoshida H, Zhou E, Tajima K. Anatomy of the energetic driving force for charge generation in organic solar cells. Nat Commun 2019; 10:2520. [PMID: 31175294 PMCID: PMC6555791 DOI: 10.1038/s41467-019-10434-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 05/11/2019] [Indexed: 11/29/2022] Open
Abstract
Eliminating the excess energetic driving force in organic solar cells leads to a smaller energy loss and higher device performance; hence, it is vital to understand the relation between the interfacial energetics and the photoelectric conversion efficiency. In this study, we systematically investigate 16 combinations of four donor polymers and four acceptors in planar heterojunction. The charge generation efficiency and its electric field dependence correlate with the energy difference between the singlet excited state and the interfacial charge transfer state. The threshold energy difference is 0.2 to 0.3 eV, below which the efficiency starts dropping and the charge generation becomes electric field-dependent. In contrast, the charge generation efficiency does not correlate with the energy difference between the charge transfer and the charge-separated states, indicating that the binding of the charge pairs in the charge transfer state is not the determining factor for the charge generation.
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Affiliation(s)
- Kyohei Nakano
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Yujiao Chen
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Bo Xiao
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, 100190, Beijing, People's Republic of China
| | - Weining Han
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
| | - Jianming Huang
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Hiroyuki Yoshida
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
| | - Erjun Zhou
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, 100190, Beijing, People's Republic of China.
| | - Keisuke Tajima
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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21
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Yao H, Cui Y, Qian D, Ponseca CS, Honarfar A, Xu Y, Xin J, Chen Z, Hong L, Gao B, Yu R, Zu Y, Ma W, Chabera P, Pullerits T, Yartsev A, Gao F, Hou J. 14.7% Efficiency Organic Photovoltaic Cells Enabled by Active Materials with a Large Electrostatic Potential Difference. J Am Chem Soc 2019; 141:7743-7750. [DOI: 10.1021/jacs.8b12937] [Citation(s) in RCA: 281] [Impact Index Per Article: 56.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Huifeng Yao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Yong Cui
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deping Qian
- Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping 58183, Sweden
| | - Carlito S. Ponseca
- Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping 58183, Sweden
| | - Alireza Honarfar
- Division of Chemical Physics, Kemicentrum, Lund University, Lund SE-22100, Sweden
| | - Ye Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingming Xin
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China
| | - Zhenyu Chen
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China
| | - Ling Hong
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bowei Gao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Runnan Yu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yunfei Zu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Ma
- State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China
| | - Pavel Chabera
- Division of Chemical Physics, Kemicentrum, Lund University, Lund SE-22100, Sweden
| | - Tönu Pullerits
- Division of Chemical Physics, Kemicentrum, Lund University, Lund SE-22100, Sweden
| | - Arkady Yartsev
- Division of Chemical Physics, Kemicentrum, Lund University, Lund SE-22100, Sweden
| | - Feng Gao
- Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping 58183, Sweden
| | - Jianhui Hou
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, China
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22
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23
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Dong Y, Cha H, Zhang J, Pastor E, Tuladhar PS, McCulloch I, Durrant JR, Bakulin AA. The binding energy and dynamics of charge-transfer states in organic photovoltaics with low driving force for charge separation. J Chem Phys 2019; 150:104704. [DOI: 10.1063/1.5079285] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yifan Dong
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hyojung Cha
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jiangbin Zhang
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Ernest Pastor
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Pabitra Shakya Tuladhar
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Iain McCulloch
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
- Physical Sciences and Engineering Division, KAUST Solar Centre (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - James R. Durrant
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
- SPECIFIC IKC, College of Engineering, Swansea University, Swansea SA12 7AX, United Kingdom
| | - Artem A. Bakulin
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
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24
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Huang J, Mo Y, Yao Y. Charge-transfer state dynamics in all-polymer solar cells: formation, dissociation and decoherence. Phys Chem Chem Phys 2019; 21:2755-2763. [PMID: 30666324 DOI: 10.1039/c8cp06467a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
All-polymer solar cells have made substantial achievements in recent years, offering numerous unsettled subjects for mechanical researchers. In order to quantitatively study the influence of the molecular electrostatic potential on the charge generation proposed by the experimenter, we simulate the ultrafast dynamics of the charge-transfer (CT) state at the interface between two polymer chains, which are respectively regarded as the donor and acceptor in all-polymer solar cells. The formation of a stable CT state is found to be sensitive to the distance between two oppositely charged polarons and the relevant critical electrostatic potential is thus quantified, which is in good agreement with experiments. In order to get insight into the dependence of the dissociation of the CT state on the width of the interfacial layer, two quantities are calculated: one is the Coulomb capture radius between the two polarons and the other is the quantum trace distance which serves as the fingerprint of the quantum coherence between them. The dissociation of the CT state is found to take place within an ultrafast timescale for an optimum interfacial width. The classical spatial distance and the quantum trace distance manifest a converging trend, suggesting a decoherence scenario for the charge separation in all-polymer solar cells.
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Affiliation(s)
- Jiaqing Huang
- Department of Physics and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China.
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25
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Yang W, Yao Y, Guo P, Sun H, Luo Y. Optimum driving energy for achieving balanced open-circuit voltage and short-circuit current density in organic bulk heterojunction solar cells. Phys Chem Chem Phys 2018; 20:29866-29875. [PMID: 30468215 DOI: 10.1039/c8cp05145c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organic bulk heterojunction solar cells generally suffer from a trade-off between the open circuit voltage (Voc) and the short circuit current density (Jsc) under a given donor/acceptor (D/A) interfacial energetic offset (or the so-called driving force). Here we theoretically investigate the optimum driving energy required for achieving the balanced Jsc and Voc simultaneously. To this end, the Jscversus the driving force ΔE curves are calculated under two different charge separation mechanisms by employing the drift-diffusion method. For the Marcus incoherent mechanism, the curve features a high plateau in a broad range of ΔE starting from 0.2 eV, which is due to the accumulation of undissociated excitons within their lifetime and signifies the possibility of obtaining a sizable Jsc under a ΔE value much smaller than the reorganization energy. After incorporating both the electron and hole transfer pathways into the device model, the calculated J-V curves are comparable to experimentally measured ones foractual blended systems of different driving forces. For the coherent mechanism, it is demonstrated that the maximum Jsc can also be achieved under the ΔE of 0.2 eV if a large proportion of the high-lying delocalized states are harvested through tuning the density of states for the charge transfer excitons to reduce the sub-gap states. This theoretical work revealed quantitatively the relationship between the interfacial energy offsets and device performance, and also provides some guidelines for identifying the macroscopic features of the actual charge separation mechanisms in bulk heterojunction solar cells.
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Affiliation(s)
- Wenchao Yang
- Key Laboratory of Microelectronics and Energy of Henan, School of Physics and Electronic Engineering, Xinyang Normal University, Xinyang, 464000, China.
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26
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Aplan MP, Munro JM, Lee Y, Brigeman AN, Grieco C, Wang Q, Giebink NC, Dabo I, Asbury JB, Gomez ED. Revealing the Importance of Energetic and Entropic Contributions to the Driving Force for Charge Photogeneration. ACS APPLIED MATERIALS & INTERFACES 2018; 10:39933-39941. [PMID: 30360072 DOI: 10.1021/acsami.8b12077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Despite significant recent progress, much about the mechanism for charge photogeneration in organic photovoltaics remains unknown. Here, we use conjugated block copolymers as model systems to examine the effects of energetic and entropic driving forces in organic donor-acceptor materials. The block copolymers are designed such that an electron donor block and an electron acceptor block are covalently linked, embedding a donor-acceptor interface within the molecular structure. This enables model studies in solution where processes occurring between one donor and one acceptor are examined. First, energy levels and dielectric constants that govern the driving force for charge transfer are systematically tuned and charge transfer within individual block copolymer chains is quantified. Results indicate that in isolated chains, a significant driving force of ∼0.3 eV is necessary to facilitate significant exciton dissociation to charge-transfer states. Next, block copolymers are cast into films, allowing for intermolecular interactions and charge delocalization over multiple chains. In the solid state, charge transfer is significantly enhanced relative to isolated block copolymer chains. Using Marcus Theory, we conclude that changes in the energetic driving force alone cannot explain the increased efficiency of exciton dissociation to charge-transfer states in the solid state. This implies that increasing the number of accessible states for charge transfer introduces an entropic driving force that can play an important role in the charge-generation mechanism of organic materials, particularly in systems where the excited state energy level is close to that of the charge-transfer state.
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27
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Inganäs O. Organic Photovoltaics over Three Decades. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1800388. [PMID: 29938847 DOI: 10.1002/adma.201800388] [Citation(s) in RCA: 235] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/20/2018] [Indexed: 05/20/2023]
Abstract
The development of organic semiconductors for photovoltaic devices, over the last three decades, has led to unexpected performance for an alternative choice of materials to convert sunlight to electricity. New materials and developed concepts have improved the photovoltage in organic photovoltaic devices, where records are now found above 13% power conversion efficiency in sunlight. The author has stayed with the topic of organic materials for energy conversion and energy storage during these three decades, and makes use of the Hall of Fame now built by Advanced Materials, to present his view of the path travelled over this time, including motivations, personalities, and ambitions.
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Affiliation(s)
- Olle Inganäs
- Biomolecular and Organic Electronics, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83, Linköping, Sweden
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28
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Kurpiers J, Ferron T, Roland S, Jakoby M, Thiede T, Jaiser F, Albrecht S, Janietz S, Collins BA, Howard IA, Neher D. Probing the pathways of free charge generation in organic bulk heterojunction solar cells. Nat Commun 2018; 9:2038. [PMID: 29795114 PMCID: PMC5966440 DOI: 10.1038/s41467-018-04386-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 04/24/2018] [Indexed: 11/30/2022] Open
Abstract
The fact that organic solar cells perform efficiently despite the low dielectric constant of most photoactive blends initiated a long-standing debate regarding the dominant pathways of free charge formation. Here, we address this issue through the accurate measurement of the activation energy for free charge photogeneration over a wide range of photon energy, using the method of time-delayed collection field. For our prototypical low bandgap polymer:fullerene blends, we find that neither the temperature nor the field dependence of free charge generation depend on the excitation energy, ruling out an appreciable contribution to free charge generation though hot carrier pathways. On the other hand, activation energies are on the order of the room temperature thermal energy for all studied blends. We conclude that charge generation in such devices proceeds through thermalized charge transfer states, and that thermal energy is sufficient to separate most of these states into free charges. Contradictory models are being debated on the dominant pathways of charge generation in organic solar cells. Here Kurpiers et al. determine the activation energy for this fundamental process and reveal that the main channel is via thermalized charge transfer states instead of hot exciton dissociation.
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Affiliation(s)
- Jona Kurpiers
- Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Thomas Ferron
- Department of Physics and Astronomy, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA
| | - Steffen Roland
- Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Marius Jakoby
- Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology (IMT), Hermann-von-Helmholtz Platz-1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Tobias Thiede
- Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Frank Jaiser
- Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany
| | - Steve Albrecht
- Helmholtz-Zentrum Berlin für Materialien und Energie, Nachwuchsgruppe Perowskit Tandemsolarzellen, Kekuléstraße 5, 12489, Berlin, Germany
| | - Silvia Janietz
- Fraunhofer IAP, Polymere und Elektronik, Geiselbergstraße 69, 14476, Potsdam-Golm, Germany
| | - Brian A Collins
- Department of Physics and Astronomy, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA
| | - Ian A Howard
- Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology (IMT), Hermann-von-Helmholtz Platz-1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Dieter Neher
- Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany.
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29
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Kim H, Park HG, Maeng MJ, Kang YR, Park KR, Choi J, Park Y, Kim YD, Kim C. Multifunctional Bilayer Template for Near-Infrared-Sensitive Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:16681-16689. [PMID: 29676150 DOI: 10.1021/acsami.8b03468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
For organic solar cells (OSCs) based on nonplanar phthalocyanines, it has previously been reported that a thin film composed of triclinic crystals with face-on (or flat-lying)-oriented molecules, typically obtained with a CuI template layer, is desired for optical absorption in the near-infrared (NIR) spectral region. However, this work demonstrates that for a PbPc-C60 donor-acceptor pair, less face-on orientation with a broader orientation distribution obtained with a new template layer consisting of a ZnPc/CuI bilayer is more desirable in terms of solar cell efficiency than the face-on orientation. A NIR-sensitive PbPc-C60 OSC employing this bilayer-templated PbPc film is found to increase the internal quantum efficiency (IQE) by 36% on average in the NIR spectral region compared to a device using a CuI-templated PbPc film. Analyses of the change in IQE using the exciton diffusion model and the entropy- and disorder-driven charge-separation model suggest that the improved IQE is attributed to the facilitated dissociation of charge-transfer excitons as well as the reduction in exciton quenching near the indium tin oxide surface.
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Affiliation(s)
- Hyungchae Kim
- Graduate School of Convergence Science and Technology, and Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Republic of Korea
| | - Han Gyeol Park
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Min-Jae Maeng
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Yu Ri Kang
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Kyung Ryoul Park
- Graduate School of Convergence Science and Technology, and Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Republic of Korea
| | - Junho Choi
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Yongsup Park
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Young Dong Kim
- Department of Physics and Research Institute of Basic Sciences , Kyung Hee University , Seoul 02453 , Republic of Korea
| | - Changsoon Kim
- Graduate School of Convergence Science and Technology, and Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Republic of Korea
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30
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Yao H, Qian D, Zhang H, Qin Y, Xu B, Cui Y, Yu R, Gao F, Hou J. Critical Role of Molecular Electrostatic Potential on Charge Generation in Organic Solar Cells. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800015] [Citation(s) in RCA: 131] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Huifeng Yao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
| | - Deping Qian
- Department of Physics, Chemistry and Biology (IFM); Linköping University; Linköping 58183 Sweden
| | - Hao Zhang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Yunpeng Qin
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Bowei Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
| | - Yong Cui
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Runnan Yu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Feng Gao
- Department of Physics, Chemistry and Biology (IFM); Linköping University; Linköping 58183 Sweden
| | - Jianhui Hou
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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31
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Boström EV, Mikkelsen A, Verdozzi C, Perfetto E, Stefanucci G. Charge Separation in Donor-C 60 Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations. NANO LETTERS 2018; 18:785-792. [PMID: 29266952 DOI: 10.1021/acs.nanolett.7b03995] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We use the nonequilibrium Green function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent density matrix renormalization group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical nonlocal correlation corrections are included. This CS process occurs in ∼10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicates that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.
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Affiliation(s)
- Emil Viñas Boström
- Lund University , Department of Physics and European Theoretical Spectroscopy Facility (ETSF), P.O. Box 118, 221 00 Lund, Sweden
| | - Anders Mikkelsen
- Lund University , Department of Physics and NanoLund, P.O. Box 118, 221 00 Lund, Sweden
| | - Claudio Verdozzi
- Lund University , Department of Physics and European Theoretical Spectroscopy Facility (ETSF), P.O. Box 118, 221 00 Lund, Sweden
| | - Enrico Perfetto
- CNR-ISM , Division of Ultrafast Processes in Materials (FLASHit), Area della Ricerca di Roma 1, Via Salaria Km 29.3, I-00016 Monterotondo Scalo, Italy
- Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Università di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Gianluca Stefanucci
- Dipartimento di Fisica and European Theoretical Spectroscopy Facility (ETSF), Università di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
- INFN, Sezione di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Rome, Italy
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32
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Liu D, Wang Q, Traverse CJ, Yang C, Young M, Kuttipillai PS, Lunt SY, Hamann TW, Lunt RR. Impact of Ultrathin C 60 on Perovskite Photovoltaic Devices. ACS NANO 2018; 12:876-883. [PMID: 29286630 DOI: 10.1021/acsnano.7b08561] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Halide perovskite solar cells have seen dramatic progress in performance over the past several years. Certified efficiencies of inverted structure (p-i-n) devices have now exceeded 20%. In these p-i-n devices, fullerene compounds are the most popular electron-transfer materials. However, the full function of fullerenes in perovskite solar cells is still under investigation, and the mechanism of photocurrent hysteresis suppression by fullerene remains unclear. In previous reports, thick fullerene layers (>20 nm) were necessary to fully cover the perovskite film surface to make good contact with perovskite film and avoid large leakage currents. In addition, the solution-processed fullerene layer has been broadly thought to infiltrate into the perovskite film to passivate traps on grain boundary surfaces, causing suppressed photocurrent hysteresis. In this work, we demonstrate an efficient perovskite photovoltaic device with only 1 nm C60 deposited by vapor deposition as the electron-selective material. Utilizing a combination of fluorescence microscopy and impedance spectroscopy, we show that the ultrathin C60 predominately acts to extract electrons from the perovskite film while concomitantly suppressing the photocurrent hysteresis by reducing space charge accumulation at the interface. This work ultimately helps to clarify the dominant role of fullerenes in perovskite solar cells while simplifying perovskite solar cell design to reduce manufacturing costs.
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Affiliation(s)
- Dianyi Liu
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Qiong Wang
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Christopher J Traverse
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Chenchen Yang
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Margaret Young
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Padmanaban S Kuttipillai
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Sophia Y Lunt
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Thomas W Hamann
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
| | - Richard R Lunt
- Department of Chemical Engineering and Materials Science, ‡Department of Chemistry, §Department of Biochemistry and Molecular Biology, and ∥Department of Physics and Astronomy, Michigan State University , East Lansing, Michigan 48824, United States
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33
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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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34
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Scharber MC, Sarciftci NS. Bulk Heterojunction Organic Solar Cells: Working Principles and Power Conversion Efficiencies. NANOSTRUCTURED MATERIALS FOR TYPE III PHOTOVOLTAICS 2017. [DOI: 10.1039/9781782626749-00033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Bulk heterojunction solar cells are a promising low-cost photovoltaic technology. This chapter discusses the efficiency potential, the role of nanomorphology and approaches to increase the power conversion efficiency of bulk heterojunction solar cells. The stacking of devices on top of each other – constructing the so-called tandem cell – appears to be one of the best ways to reach the power conversion efficiencies necessary for the large-scale commercialization of this technology.
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Affiliation(s)
- M. C. Scharber
- Linz Institute of Organic Solar Cells, Physical Chemistry, Johannes Kepler University Linz Altenbergerstrasse 69 4040 Linz Austria
| | - N. S. Sarciftci
- Linz Institute of Organic Solar Cells, Physical Chemistry, Johannes Kepler University Linz Altenbergerstrasse 69 4040 Linz Austria
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35
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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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36
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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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37
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Yao Y, Xie X, Ma H. Ultrafast Long-Range Charge Separation in Organic Photovoltaics: Promotion by Off-Diagonal Vibronic Couplings and Entropy Increase. J Phys Chem Lett 2016; 7:4830-4835. [PMID: 27934051 DOI: 10.1021/acs.jpclett.6b02400] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The exciton dissociation in a model donor/acceptor heterojunction with electron-phonon couplings is simulated by a full quantum dynamical method, in which ultrafast long-range charge separation is observed. Such a novel scenario does not undergo short-range interfacial (pinned) charge transfer states, but can be mainly ascribed to the quantum resonance between local Frenkel excited states and a broad array of long-range charge transfer (LRCT) states assisted by the moderate off-diagonal vibronic couplings. The entropy-increasing effect associated with the very dense density of states for LRCT states is also found to be beneficial for lowering the free energy barrier for charge generation in organic solar cells.
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Affiliation(s)
- Yao Yao
- Department of Physics, South China University of Technology , Guangzhou 510640, China
| | - Xiaoyu Xie
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China
| | - Haibo Ma
- Key Laboratory of Mesoscopic Chemistry of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China
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38
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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39
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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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40
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Roles of Energy/Charge Cascades and Intermixed Layers at Donor/Acceptor Interfaces in Organic Solar Cells. Sci Rep 2016; 6:29529. [PMID: 27404948 PMCID: PMC4941572 DOI: 10.1038/srep29529] [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: 04/04/2016] [Accepted: 06/17/2016] [Indexed: 01/10/2023] Open
Abstract
The secret to the success of mixed bulk heterojunctions (BHJs) in yielding highly efficient organic solar cells (OSCs) could reside in the molecular structures at their donor/acceptor (D/A) interfaces. In this study, we aimed to determine the effects of energy and charge cascade structures at the interfaces by using well-defined planar heterojunctions (PHJs) as a model system. The results showed that (1) the charge cascade structure enhanced VOC because it shuts down the recombination pathway through charge transfer (CT) state with a low energy, (2) the charge cascade layer having a wider energy gap than the bulk material decreased JSC because the diffusion of the excitons from the bulk to D/A interface was blocked; the energy of the cascade layers must be appropriately arranged for both the charges and the excitons, and (3) molecular intermixing in the cascade layer opened the recombination path through the low-energy CT state and decreased VOC. Based on these findings, we propose improved structures for D/A interfaces in BHJs.
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