Tuning Solid Additive Side-Chain Length to Optimize Acceptor Stacking Morphology for Over 20% Efficiency in Organic Solar Cells
Miaoxuan Wu , Jingjie Su , Zihao Xia , Hansheng Chen , Jiang Zhou , Huawei Hu , Wenduo Chen , Chen Xie , Shenghua Liu
Chinese Journal of Chemistry ›› 2026, Vol. 44 ›› Issue (1) : 119 -128.
The incorporation of solid additive in photoactive layer as an effective strategy has been successfully employed to optimize the formation of a bi-continuous interpenetrating network morphology in blend bulk heterojunction, which is a critical determinant of photovoltaic performance in organic solar cells (OSCs). However, the influence of additive side-chain length on the morphological evolution remains insufficiently understood. In this work, we propose two novel solid additives, 1,3,5-tribromobenzene (TBB) and 1,3,5-tris(bromomethyl)benzene (TBMB) with different side-chain lengths. Theoretical calculations reveal that TBMB, featuring longer side-chain length, demonstrates stronger non-covalent intermolecular interaction with donors and acceptors compared to TBB, thereby favoring optimized molecular aggregation and crystallization behavior during film formation. As a result, the TBMB-treated device achieves a champion power conversion efficiency (PCE) of 17.92% in PM6:Y6 system, outperforming the TBB-treated counterpart (17.20%). Remarkably, TBMB exhibits universal effectiveness across other systems, achieving an exceptional efficiency of 20.04% in D18:L8-BO-based device. This work provides deep insights into the potential working mechanism of solid additives with precise side-chain length modulation, establishing a valuable additive side-chain effects for future research on morphology regulation in OSCs.
Organic solar cells / Bulk heterojunction / Solid additive / Side-chain length / π–π stacking / Aggregation
2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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