Enhanced Hole Transport in Ternary Blend Polymer Solar Cells

Abstract

Recently, ternary blend polymer solar cells have attracted great attention to improve a short‐circuit current density (JSC) effectively, because complementary absorption bands can harvest the solar light over a wide wavelength range from visible to near‐IR region. Interestingly, some ternary blend solar cells have shown improvements not only in JSC but also in fill factor (FF). Previously, we also reported that a ternary blend solar cell based on a low‐bandgap polymer (PTB7‐Th), a wide‐bandgap polymer (PDCBT), and a fullerene derivative (PCBM) exhibited a higher FF than their binary analogues. Herein, we study charge transport in PTB7‐Th/PDCBT/PCBM ternary blend films to address the origin of the improvement in FF. We found that hole polarons are located in PTB7‐Th domains and their mobility is enhanced in the ternary blend film.