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

Research output: Contribution to journalArticlepeer-review

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%).

Original languageEnglish (US)
Article number2205926
JournalAdvanced Materials
Volume34
Issue number42
DOIs
StatePublished - Oct 20 2022

Keywords

  • charge transport
  • exciton diffusion
  • fused-ring electron acceptors
  • organic solar cells
  • organoboron

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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