Tianyu Hu, Xufan Zheng, Ting Wang, Aziz Saparbaev, Bowen Gao, Jingnan Wu, Jingyi Xiong, Ming Wan, Tingting Cong, Yuda Li, Ergang Wang, Xunchang Wang, Renqiang Yang
{"title":"Steric hindrance induced low exciton binding energy enables low-driving-force organic solar cells","authors":"Tianyu Hu, Xufan Zheng, Ting Wang, Aziz Saparbaev, Bowen Gao, Jingnan Wu, Jingyi Xiong, Ming Wan, Tingting Cong, Yuda Li, Ergang Wang, Xunchang Wang, Renqiang Yang","doi":"10.1002/agt2.632","DOIUrl":null,"url":null,"abstract":"<p>Exciton binding energy (<i>E</i><sub>b</sub>) has been regarded as a critical parameter in charge separation during photovoltaic conversion. Minimizing the <i>E</i><sub>b</sub> of the photovoltaic materials can facilitate the exciton dissociation in low-driving force organic solar cells (OSCs) and thus improve the power conversion efficiency (PCE); nevertheless, diminishing the <i>E</i><sub>b</sub> with deliberate design principles remains a significant challenge. Herein, bulky side chain as steric hindrance structure was inserted into Y-series acceptors to minimize the <i>E</i><sub>b</sub> by modulating the intra- and intermolecular interaction. Theoretical and experimental results indicate that steric hindrance-induced optimal intra- and intermolecular interaction can enhance molecular polarizability, promote electronic orbital overlap between molecules, and facilitate delocalized charge transfer pathways, thereby resulting in a low <i>E</i><sub>b</sub>. The conspicuously reduced <i>E</i><sub>b</sub> obtained in Y-ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low-driving-force OSCs, achieving a remarkable PCE of 19.1% with over 95% internal quantum efficiency. Our study provides a new molecular design rationale to reduce the <i>E</i><sub>b</sub>.</p>","PeriodicalId":72127,"journal":{"name":"Aggregate (Hoboken, N.J.)","volume":null,"pages":null},"PeriodicalIF":13.9000,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/agt2.632","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Aggregate (Hoboken, N.J.)","FirstCategoryId":"1085","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/agt2.632","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Exciton binding energy (Eb) has been regarded as a critical parameter in charge separation during photovoltaic conversion. Minimizing the Eb of the photovoltaic materials can facilitate the exciton dissociation in low-driving force organic solar cells (OSCs) and thus improve the power conversion efficiency (PCE); nevertheless, diminishing the Eb with deliberate design principles remains a significant challenge. Herein, bulky side chain as steric hindrance structure was inserted into Y-series acceptors to minimize the Eb by modulating the intra- and intermolecular interaction. Theoretical and experimental results indicate that steric hindrance-induced optimal intra- and intermolecular interaction can enhance molecular polarizability, promote electronic orbital overlap between molecules, and facilitate delocalized charge transfer pathways, thereby resulting in a low Eb. The conspicuously reduced Eb obtained in Y-ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low-driving-force OSCs, achieving a remarkable PCE of 19.1% with over 95% internal quantum efficiency. Our study provides a new molecular design rationale to reduce the Eb.