Engineering the Core Units of Small‐Molecule Acceptors to Enhance the Performance of Organic Photovoltaics. Issue 10 (6th August 2020)

• Record Type: Journal Article
• Authors: Wang, Hao-Cheng; Chen, Chung-Hao; Li, Ren-Hao; Lin, Yu-Che; Tsao, Cheng-Si; Chang, Bin; Tan, Shaun; Yang, Yang; Wei, Kung-Hwa
• Is Part Of: Solar RRL. Volume 4:Issue 10(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-08-06
• Subjects: core units -- grazing-incidence X-ray scattering -- morphologies -- organic solar cells -- small-molecule acceptors; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202000253
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Understanding the chemical structures of next‐generation small molecules is a critical step for increasing the performance of organic photovoltaics (OPVs); an OPV's small molecule determines not only the extent of light absorption but also the morphology. Herein, four small molecules featuring different cores—indaceno dithiophene, dithienoindeno indaceno dithiophene (IDTT), substituted IDTT, and dithienothiophene‐pyrrolobenzothiadiazole—denoted as ID‐4Cl, IT‐4Cl, m‐ITIC‐OR‐4Cl, and Y7, respectively, are selected to form active layers with poly(quinoxaline) (PTQ10) and poly(benzodithiophene‐4, 8‐dione) (PM6). The Y7 devices exhibit the best performance in both systems, with the power conversion efficiency (PCE) reaching 14.5%; in comparison, ID‐4Cl device gives a PCE of 10.0% for blending with PTQ10 and a relative efficiency enhancement of 45%. The same trend occurs for the cases of PM6 blend devices. This enhancement is attributed to i) the improved short‐circuit current density that is provided by the greater degree of conjugation in S, N‐heteroarenes ladder‐type fused‐ring cores of Y7, ii) an induced face‐on Y7 orientation and smaller domain sizes that result from the sp 2 ‐hybridized nitrogen side chain, and iii) smaller energy loss. This study reveals the importance of the core structure on the device performance and provides guidelines for the design of new materials for OPV technologies. Abstract : Understanding the chemical structures of next‐generation small molecules will be a critical step for increasing the performance of organic photovoltaics (OPVs). This study reveals the importance of core structure on the device performance, and provides guidelines for the design of new materials for OPV technologies.