Molecular geometry regulation of bay-phenyl substituted perylenediimide derivatives with bulky alkyl chain for use in organic solar cells as the electron acceptor

摘要: Abstract Perylenediimide derivatives (PDI) are among the most promising non-fullerene electron acceptor materials for use in organic solar cells. However, owing to intensive intermolecular interactions, non-functionalized PDI molecules showed high tendency of aggregation solid film, which leads poor device performance. In this paper molecular geometry was finely tuned by introducing a bulky isopropyl group on bay-phenyl unit, and influences such alkyl optical electrochemical properties were systematically studied. Results indicated that para- meta-position has negligible influence twist angle between core these two compounds (4-iPP-PDI 3-iPP-PDI) have similar properties. large steric hindrance ortho-isopropyl causes conjugation break, consequently blue-shifted absorption spectrum an increased band gap final compound (2-iPP-PDI). Polymer cells using functionalized PDIs as fabricated tested. And meta-substituted 3-iPP-PDI show better performance than ortho-substituted 2-iPP-PDI), ascribed proper nano-scale phase separation mobility blended film. The current results proved can be regulated through side chain bay-substitution achieve balanced property crystallinity mobility.