The role of interfacial donor–acceptor percolation in efficient and stable all-polymer solar cells

Zhen Wang, Yu Guo, Xianzhao Liu, Wenchao Shu, Guangchao Han, Kan Ding, Subhrangsu Mukherjee, Nan Zhang, Hin-Lap Yip, Yuanping Yi, Harald Ade, Philip C. Y. Chow*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

21 Citations (Scopus)
14 Downloads (CityUHK Scholars)

Abstract

Polymerization of Y6-type acceptor molecules leads to bulk-heterojunction organic solar cells with both high power-conversion efficiency and device stability, but the underlying mechanism remains unclear. Here we show that the exciton recombination dynamics of polymerized Y6-type acceptors (Y6-PAs) strongly depends on the degree of aggregation. While the fast exciton recombination rate in aggregated Y6-PA competes with electron-hole separation at the donor–acceptor (D–A) interface, the much-suppressed exciton recombination rate in dispersed Y6-PA is sufficient to allow efficient free charge generation. Indeed, our experimental results and theoretical simulations reveal that Y6-PAs have larger miscibility with the donor polymer than Y6-type small molecular acceptors, leading to D–A percolation that effectively prevents the formation of Y6-PA aggregates at the interface. Besides enabling high charge generation efficiency, the interfacial D–A percolation also improves the thermodynamic stability of the blend morphology, as evident by the reduced device “burn-in” loss upon solar illumination. © The Author(s) 2024.
Original languageEnglish
Article number1212
JournalNature Communications
Volume15
Online published8 Feb 2024
DOIs
Publication statusPublished - 2024

Funding

P.C.Y.C. acknowledges support from the Hong Kong Research Grant Council (27200822, 16300023), National Natural Science Foundation of China (22222905), and the University Research Council of the University of Hong Kong (HKU). Z.W. acknowledges support from Hong Kong Innovation and Technology Fund (MHP/064/20). Y.Y. acknowledges the support from the National Natural Science Foundation of China (22173108), and G.H. acknowledges the support from the Youth Innovation Promotion Association, CAS (2023037). H.-L.Y. acknowledges support from the Hong Kong Research Grant Council (11307323). X-ray data was acquired at the Advanced Light Source, Lawrence Berkeley National Laboratory, which was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under contract no. DE-AC02-05CH11231. The authors acknowledge Dr Christopher C.S. Chan for his help with optical experiments. Publication made possible in part by support from the HKU Libraries Open Access Author Fund sponsored by the HKU Libraries.

Publisher's Copyright Statement

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