Simultaneously Enhancing Exciton/Charge Transport in Organic Solar Cells by an Organoboron Additive

Heng Lu; Kai Chen; Raja Sekhar Bobba; Jiangjian Shi; Mengyang Li; Yilin Wang; Jingwei Xue; Peiyao Xue; Xiaojian Zheng; Karen E Thorn; Isabella Wagner; Chao-Yang Lin; Yin Song; Wei Ma; Zheng Tang; Qingbo Meng; Quinn Qiao; Justin M Hodgkiss; Xiaowei Zhan

doi:10.1002/adma.202205926

Simultaneously Enhancing Exciton/Charge Transport in Organic Solar Cells by an Organoboron Additive

Adv Mater. 2022 Oct;34(42):e2205926. doi: 10.1002/adma.202205926. Epub 2022 Sep 16.

Authors

Heng Lu¹, Kai Chen^{2

3}, Raja Sekhar Bobba⁴, Jiangjian Shi⁵, Mengyang Li⁶, Yilin Wang⁷, Jingwei Xue⁷, Peiyao Xue¹, Xiaojian Zheng¹, Karen E Thorn², Isabella Wagner², Chao-Yang Lin³, Yin Song⁸, Wei Ma⁷, Zheng Tang⁶, Qingbo Meng⁵, Quinn Qiao⁴, Justin M Hodgkiss², Xiaowei Zhan^{1

9}

Affiliations

¹ School of Materials Science and Engineering, Peking University, Beijing, 100871, China.
² MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6010, New Zealand.
³ Robinson Research Institute, Faculty of Engineering, Victoria University of Wellington, Wellington, 6010, New Zealand.
⁴ Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, 13244, USA.
⁵ CAS Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
⁶ Center for Advanced Low-Dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, China.
⁷ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
⁸ School of Optics and Photonics, Beijing Institute of Technology, Beijing, 100081, China.
⁹ Key Laboratory of Eco-functional Polymer Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, China.

PMID: 36027579
DOI: 10.1002/adma.202205926

Abstract

Efficient exciton diffusion and charge transport play a vital role in advancing the power conversion efficiency (PCE) of organic solar cells (OSCs). Here, a facile strategy is presented to simultaneously enhance exciton/charge transport of the widely studied PM6:Y6-based OSCs by employing highly emissive trans-bis(dimesitylboron)stilbene (BBS) as a solid additive. BBS transforms the emissive sites from a more H-type aggregate into a more J-type aggregate, which benefits the resonance energy transfer for PM6 exciton diffusion and energy transfer from PM6 to Y6. Transient gated photoluminescence spectroscopy measurements indicate that addition of BBS improves the exciton diffusion coefficient of PM6 and the dissociation of PM6 excitons in the PM6:Y6:BBS film. Transient absorption spectroscopy measurements confirm faster charge generation in PM6:Y6:BBS. Moreover, BBS helps improve Y6 crystallization, and current-sensing atomic force microscopy characterization reveals an improved charge-carrier diffusion length in PM6:Y6:BBS. Owing to the enhanced exciton diffusion, exciton dissociation, charge generation, and charge transport, as well as reduced charge recombination and energy loss, a higher PCE of 17.6% with simultaneously improved open-circuit voltage, short-circuit current density, and fill factor is achieved for the PM6:Y6:BBS devices compared to the devices without BBS (16.2%).

Keywords: charge transport; exciton diffusion; fused-ring electron acceptors; organic solar cells; organoboron.

Abstract

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