Microscopic Structures, Dynamics, and Spin Configuration of the Charge Carriers in Organic Photovoltaic Solar Cells Studied by Advanced Time-Resolved Spectroscopic Methods

Ohta, Kaoru; Tominaga, Kazuhiro; Ikoma, Tadaaki; Kobori, Yasuhiro; Yamada, Hiroko

doi:10.1021/acs.langmuir.2c00290

Cited by 14 publications

(14 citation statements)

References 103 publications

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“…In addition, the present collective phonon’s role is very consistent with k CS > 1 ps –1 in Figure a, which is quicker than the exciton-diffusions. This is also supported by the ultrafast carrier dynamics studied by terahertz spectroscopy. , …”

Section: Discussionmentioning

confidence: 58%

Nonpolymer Organic Solar Cells: Microscopic Phonon Control to Suppress Nonradiative Voltage Loss via Charge-Separated State

et al. 2022

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Recent remarkable developments on nonfullerene solar cells have reached a photoelectric conversion efficiency (PCE) of 18% by tuning the band energy levels in small molecular acceptors. In this regard, understanding the impact of small donor molecules on nonpolymer solar cells is essential. Here, we systematically investigated mechanisms of solar cell performance using diketopyrrolopyrrole (DPP)–tetrabenzoporphyrin (BP) conjugates of C4-DPP–H2BP and C4-DPP–ZnBP, where C4 represents the butyl group substituted at the DPP unit as small p-type molecules, while an acceptor of [6,6]-phenyl-C61-buthylic acid methyl ester is employed. We clarified the microscopic origins of the photocarrier caused by phonon-assisted one-dimensional (1D) electron–hole dissociations at the donor–acceptor interface. Using a time-resolved electron paramagnetic resonance, we have characterized controlled charge-recombination by manipulating disorders in π–π donor stacking. This ensures carrier transport through stacking molecular conformations to suppress nonradiative voltage loss capturing specific interfacial radical pairs separated by 1.8 nm in bulk-heterojunction solar cells. We show that, while disordered lattice motions by the π–π stackings via zinc ligation are essential to enhance the entropy for charge dissociations at the interface, too much ordered crystallinity causes the backscattering phonon to reduce the open-circuit voltage by geminate charge-recombination.

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Section: Discussionmentioning

confidence: 58%

Nonpolymer Organic Solar Cells: Microscopic Phonon Control to Suppress Nonradiative Voltage Loss via Charge-Separated State

et al. 2022

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“…The chemical structures of photovoltaic materials (PBDB-T, IT-M, and ST10-CN-1) are shown in Figure 1a. The synthesis route, 1 H NMR spectrum, and 13 C NMR spectrum of ST10-CN-1 are provided in the Supporting Information (Scheme S1, Figures S1 and S2). Two conjugate thiophene chains are linked by a single bond to form the capital letter X configuration in the ST10-CN-1 molecule, which can enhance the solubility, suppress the excessive crystallization, and make the films more compact.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The detailed synthesis method of ST10-CN-1 is shown in the Supporting Information. The synthetic scheme of ST10-CN-1 is shown in Scheme S1, and the 1 H NMR and 13 C NMR spectra of ST10-CN-1 are shown in Figures S1 and S2. The HOMO level of neat ST10-CN-1 can be evaluated according to the cyclic voltammetry curves, as shown in Figure S3.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Bulk heterojunction (BHJ) organic solar cells (OSCs) have evolved as prospective and affordable alternatives for emerging green energy technologies due to their advantages of abundant raw materials, low cost, light weight, flexibility, large-area fabrication by roll-to-roll manufacture, and readily tunable absorption and energy levels. − The power conversion efficiency (PCE) of fullerene-free OSCs has improved significantly over the past decade. , However, the PCE of OSCs still maintains a distance from silicon solar cells and perovskite solar cells, and it still needs improvement before it can be commercialized. − To further improve the PCE of OSCs, more efforts should be devoted to the narrow absorption region of organic materials, morphological defects, recombination traps, and the intermolecular interactions between organic molecules. − Numerous studies have addressed these problems, for instance, by developing novel materials, controlling vertical stratification in photovoltaic mix films, engineering interfaces, creating ternary devices, and developing new device architectures. − Even though tandem OSCs can significantly increase device performance, commercialization is challenging due to the complexity and difficulty of device manufacture. − To preserve the single junction structure’s simplicity while improving the active layer’s light absorption, ternary OSCs comprising three light-absorbing materials (a donor, an acceptor, and a third material) in one active layer are demonstrated as an attractive strategy. − OSCs based on ternary blends also exhibit great prospects for improving OSCs’ performance because the third component may be capable of adjusting energy levels, enhancing optical absorption range or via Förster resonance energy transfer (FRET) effect, facilitating charge transport, and optimizing phase separation of the active layer. − Nowadays, a state-of-the-art PCE exceeding 19% has been achieved in ternary OSCs, which embodies the potential meliority of the ternary strategy in improving PCE. , …”

Section: Introductionmentioning

confidence: 99%

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Optimized Morphology Enables High-Efficiency Nonfullerene Ternary Organic Solar Cells

Wang

Zhang

et al. 2022

Langmuir

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Tuning the three-dimensional morphology in the active layer is an effective method to improve the performance of bulk heterojunction organic solar cells (OSCs). In this work, an acceptor−donor−acceptor structured small molecule ST10-CN-1 was synthesized and employed as the guest donor to fabricate ternary OSCs based on a PBDB-T:IT-M host binary system. The incorporation of ST10-CN-1 could broaden the active layer's absorption range of solar light thereby leading to a promotional shortcircuit current. Moreover, adding an appropriate amount of ST10-CN-1 could effectively regulate the morphology of the active layer in both the lateral direction and vertical stratification. All of these morphological alterations helped to speed up the exciton dissociation, charge transit, and charge collecting processes, which in turn increased the power conversion efficiency. As a result, an excellent PCE of 11.5% for the ternary device based on PBDB-T:IT-M:ST10-CN-1 was obtained. The enhanced PCE was also linked to the formation of an alloylike state between PBDB-T and ST10-CN-1, as evidenced by the fact that the open circuit voltage of ternary OSCs lay between those for PBDB-T:IT-M (0.925 V) and ST10-CN-1:IT-M (1.064 V). This work illustrates that refining the morphology of the active layer by incorporating an appropriate third component is an effective way to further enhance the device's performance.

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“…OPVs, which generate clean, renewable, and sustainable energy, 33,41,45,108,156‐160 have the potential to change the organic photovoltaics market, 33 as this emerging technology has numerous benefits over conventional inorganic semiconductor‐based systems 12,138 . OPVs have a short energy payback time, 33,162 they can absorb light across the solar spectrum, 64 their fabrication cost is low 35,46,92,114,136,158,16‐169 and simple, 28,92,11,73,138,160,165,170 due to the use of abundant materials, 22 can be manufactured using solution‐based processing, 62,63,72,156,165,171,17 do not require high manufacturing temperatures,…”

Section: Organic Photovoltaic Cellsmentioning

confidence: 99%

A review on organic photovoltaic cell

Sampaio

González

2022

Intl J of Energy Research

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Summary The objective of this article is to identify how organic photovoltaic cells have been addressed in scientific studies published until 2022. To this end, a literature review was conducted, which involved the search for articles through the Advanced Search tool of the Periodicals portal of the Coordination for the Improvement of Higher Education Personnel, as well as the preparation of a Microsoft Excel spreadsheet to assist in the classifying the articles, followed by a structured analysis of the structure, operating principle, materials, performance parameters, stability/life span/degradation, challenges, opportunities, and applications of organic photovoltaic cells. The results of this research point out that organic photovoltaic devices are formed by electrodes (anode, such as indium‐tin oxide, silver nanowires, carbon nanotubes and graphene and cathode, such as calcium, barium, or aluminum), hole transport layers (PEDOT:PSS), and electrons (ZnO or the TiO2), as well as by the active layer (donor, such as P3HT or PTB7, and acceptor, such as C60 and C70 fullerenes and their PCBM derivatives, as well as non‐fulerene acceptors). We further identify that the working principle of organic photovoltaic cells consists in the generation of photocurrent from the absorption of a photon that results in an exciton, this in turn diffuses to the donor–acceptor interface, and disassociates into free carriers, which carry collected charges to the electrodes. We find that organic photovoltaic cells are simple to manufacture, less expensive, more flexible, lightweight, and that the development of these devices has advanced in recent years. However, for practical relevance, some challenges need to be overcome, including power conversion efficiency, stability, degradation, lifetime, as well as fabrication of large areas through roll‐to‐roll methods.

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Microscopic Structures, Dynamics, and Spin Configuration of the Charge Carriers in Organic Photovoltaic Solar Cells Studied by Advanced Time-Resolved Spectroscopic Methods

Cited by 14 publications

References 103 publications

Nonpolymer Organic Solar Cells: Microscopic Phonon Control to Suppress Nonradiative Voltage Loss via Charge-Separated State

Nonpolymer Organic Solar Cells: Microscopic Phonon Control to Suppress Nonradiative Voltage Loss via Charge-Separated State

Optimized Morphology Enables High-Efficiency Nonfullerene Ternary Organic Solar Cells

A review on organic photovoltaic cell

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