Ternary Nonfullerene Polymer Solar Cells with a Power Conversion Efficiency of 11.6% by Inheriting the Advantages of Binary Cells

Ternary polymer solar cells (PSCs) were commonly fabricated with two donors or two acceptors; the third component has complementary absorption spectra with a host system to improve photon harvesting. In this work, a series of nonfullerene PSCs were fabricated with J71 as the donor and IT-M and/or ITIC with an almost identical band gap as acceptors. Although IT-M and ITIC have almost identical band gaps, the two optimized binary PSCs exhibit different photovoltaic parameters. The short current density (Jsc) and open-circuit voltage (Voc) of J71:IT-M based PSCs are larger than those of J71:ITIC based PSCs; the other key parameter, the fill factor (FF), is just the opposite. The power conversion efficiency (PCE) of optimized ternary PSCs arrives at 11.60% by inheriting the advantages of binary PSCs. This work may provide a new strategy for preparing efficient nonfullerene ternary PSCs by selecting binary PSCs with complementary photovoltaic parameters.