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Research Article | Open Access

Dissociation of singlet excitons dominates photocurrent improvement in high-efficiency non-fullerene organic solar cells

Qicong Li1,2,§Shizhong Yue1,§Zhitao Huang1Chao Li1Jiaqian Sun1Keqian Dong1Zhijie Wang1( )Kong Liu1( )Shengchun Qu1( )Yong Lei3( )
Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
China Electronics Standardization Institution, Beijing 100007, China
Fachgebiet Angewandte Nanophysik, Institut für Physik & IMN MacroNano, Technische Universität Ilmenau, Ilmenau 98693, Germany

§ Qicong Li and Shizhong Yue contributed equally to this work.

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Graphical Abstract

Increasing the ratio of singlet excitons in high-efficiency non-fullerene organic solar cells enhances the photocurrent.


In organic solar cells, the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state. Therefore, the ratio of the singlet and triplet excitons directly affects the photocurrent. Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons, which shows a long diffusion length. Here we observed that in high-efficiency systems, the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light. Since the singlet charge transfer state has lower binding energy than the triplet state, it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent. Further, the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent, which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.

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Nano Research Energy
Cite this article:
Li Q, Yue S, Huang Z, et al. Dissociation of singlet excitons dominates photocurrent improvement in high-efficiency non-fullerene organic solar cells. Nano Research Energy, 2024, 3: e9120099.










Received: 09 July 2023
Revised: 23 August 2023
Accepted: 31 August 2023
Published: 22 September 2023
© The Author(s) 2023. Published by Tsinghua University Press.

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