Asymmetric indenothiophene-based non-fullerene acceptors for efficient polymer solar cells

Abstract

Three new asymmetric acceptor-donor-acceptor structured molecules are designed and synthesized by incorporating indenothiophene as the central core. Their bandgaps and energy levels can be easily tuned by varying the electron withdrawing ability of the terminal groups such as dicyanovinyl, 3-ethylrhodanine, and 2-(1,1-dicyanomethylene)-3-ethyl-rhodanine. Inverted polymer solar cells using these molecules as acceptors and PTB7-Th as a donor material afford a highest power conversion efficiency of 7.49% with a high open circuit voltage of 1.02 V as well as a low energy loss of 0.59 eV.