Enhanced performance of polymer solar cells based on PTB7-Th:PC71BM by doping with 1-bromo-4-nitrobenzene

Abstract

Organic solar cells (OSCs) have emerged as an attractive strategy to efficiently convert light energy into electricity. In this study, the third component 1-bromo-4-nitrobenzene (C₆H₄BrNO₂) was introduced into the active layer of PTB7-Th:PC₇₁BM to promote exciton separation and speed up electron transfer. A PCE of 8.95% was achieved for polymer solar cells (PSCs) with 15 wt% C₆H₄BrNO₂, which is an 18% enhancement in PCE compared with binary OSCs based on PTB7-Th:PC₇₁BM. Atomic force microscopy (AFM) measurements indicated that the ideal morphology can be formed. The charge generation properties were studied in terms of internal quantum efficiency (I_QE) and photocurrent density (J_ph), revealing that charge transport was facilitated significantly, which favors higher J_SC and FF.