Issue 11, 2024

Regulating the miscibility of donors/acceptors to manipulate the morphology and reduce non-radiative recombination energy loss enables efficient organic solar cells

Abstract

Due to the high exciton binding energy and relatively low charge carrier mobilities of organic photovoltaic materials, it is crucial to optimize the active layer morphology of organic solar cells (OSCs) to well juggle exciton dissociation and charge carrier transport, and inhibit charge carrier recombination for high power conversion efficiencies (PCEs). Herein, we efficiently improve the crystallinity and miscibility of fused ring electron acceptors (FREAs) via lengthening the side chains and developing four FREAs, BTP-nC8, BTP-C8, BTP-C12 and BTP-C20. The dual functions of lengthening the side chains of FREAs make PM6:FREA blend films present the tendency of first improving then deteriorating in crystallinity, phase separation, domain purity and thus charge carrier dynamics, which leads the JSC and FF of PM6:FREA-based OSCs to show the same trend along with the side-chain length of FREAs. More importantly, enhancing the miscibility between PM6 and FREA facilitates the spatial registry to reduce the formation and recombination rate of triplet excitons in the PM6:FREA blend films, thus inhibiting the non-radiative recombination for decreased ΔEnr, and then increasing VOC in OSCs. Among them, PM6:BTP-C8 based OSCs well balance the multiple impacts of lengthening the side chains to achieve the highest PCE of 17.77%. This work demonstrates that it is important to finely control the crystallinity and miscibility of organic photovoltaic materials to achieve high PCEs in OSCs.

Graphical abstract: Regulating the miscibility of donors/acceptors to manipulate the morphology and reduce non-radiative recombination energy loss enables efficient organic solar cells

Supplementary files

Article information

Article type
Paper
Submitted
29 N’w 2023
Accepted
12 Yan 2024
First published
14 Yan 2024

J. Mater. Chem. C, 2024,12, 3873-3880

Regulating the miscibility of donors/acceptors to manipulate the morphology and reduce non-radiative recombination energy loss enables efficient organic solar cells

Z. Han, K. Wang, Y. Chai, R. Zhang, J. Zhang, D. He, C. Wang and F. Zhao, J. Mater. Chem. C, 2024, 12, 3873 DOI: 10.1039/D3TC04810A

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