BN‐Bond‐Embedded Triplet Terpolymers with Small Singlet–Triplet Energy Gaps for Suppressing Non‐Radiative Recombination and Improving Blend Morphology in Organic Solar Cells. Issue 17 (15th March 2023)

• Record Type: Journal Article
• Authors: Pang, Bo; Liao, Chentong; Xu, Xiaopeng; Peng, Shaoqian; Xia, Jianlong; Guo, Yuanyuan; Xie, Yuan; Chen, Yuting; Duan, Chunhui; Wu, Hongbin; Li, Ruipeng; Peng, Qiang
• Is Part Of: Advanced materials. Volume 35:Issue 17(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-15
• Subjects: B N bonds -- non‐radiative recombination -- organic solar cells -- singlet–triplet energy gap -- triplet terpolymers; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202211871
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Suppressing the photon energy loss ( E loss ), especially the non‐radiative loss, is of importance to further improve the device performance of organic solar cells (OSCs). However, typical π‐conjugated semiconductors possess a large singlet–triplet energy gap (Δ E ST ), leading to a lower triplet state than charge transfer state and contributing to a non‐radiative loss channel of the photocurrent by the triplet state. Herein, a series of triplet polymer donors are developed by introducing a BNIDT block into the PM6 polymer backbone. The high electron affinity of BNIDT and the opposite resonance effect of the BN bond in BNIDT results in a lowered highest occupied molecular orbital (HOMO) and a largely reduced Δ E ST . Moreover, the morphology of the active blends is also optimized by fine‐tuning the BNIDT content. Therefore, non‐radiative recombination via the terminal triplet loss channels and morphology traps is effectively suppressed. The PNB‐3 (with 3% BNIDT):L8‐BO device exhibits both small Δ E ST and optimized morphology, favoring more efficient charge transfer and transport. Finally, the simultaneously enhanced V oc of 0.907 V, J sc of 26.59 mA cm −2, and FF of 78.86% contribute to a champion PCE of 19.02%. Therefore, introducing BN bonds into benchmark polymers is a possible avenue toward higher‐performance of OSCs. Abstract : A series of terpolymers are developed by introducing the BN bond into the polymer chain of PM6, which lowers the HOMO level, reduces the Δ E ST, and optimizes the morphology of the active blend, contributing to a high PCE of 19.02% with reduced E loss and charge recombination.