Tailoring the Electron-Deficient Central Core on Fused-Ring Nonfullerene Acceptors: Deciphering the Relationships Between Structure, Property, And Photovoltaic Performance

Abstract

In the field of organic solar cells, organic semiconductors with Y6-based chemical structure and their corresponding quinoxaline-based assemblies have been settled down as promising materials in the field of OSCs. However, the chemical structure of Y6 derivatives does not allow an expansion in the electron-withdrawing central core, in contrast to their quinoxaline-based analogues. For this reason, in this work we have designed and synthetized two different quinoxaline-based A-D-A´-D-A derivatives with two-dimensional π-extended cores endowed with electroactive rylenimide moieties, named as Y6-1Napht and Y6-1Pery. These enlarged fused-ring electron acceptors (FREAs) allowed us to study the influence of the length of the ryleneimide moiety on its structural, optical, electrochemical, and thermal properties as well as the tailoring of the frontier molecular orbitals. These results were also supported by quantum chemical calculations and photoluminescence measurements that provide additional information about their thermal stability and the microstructure of the films. Finally, as a proof-of-concept and to study the influence of these chemical modifications of the central in core, we fabricated solar cells based on these π-conjugated non-fullerene acceptors.