High‐Performance Ternary Semitransparent Polymer Solar Cells with Different Bandgap Third Component as Non‐Fullerene Guest Acceptor

Ternary semitransparent polymer solar cells (ST‐PSCs) have great potential to simultaneously improve the power conversion efficiency (PCE) and average visible transmittance (AVT). Non‐fullerene acceptor IHIC was synthesized by a simple one‐step process under low cost and had an A‐D‐A structure similar to ITIC and IT‐4F. Ternary device based on PM6:Y6:IHIC (20%) demonstrated higher hole and electron mobility (2.78, 3.12 × 10−4 cm2 V−1 S−1) and more balanced charge transport properties (μe/μh = 1.12) than the host binary device, and the ternary ST‐PSC demonstrated a PCE of 12.18% and AVT of 27.07%. Ternary PSCs with 20% ITIC or IT‐4F also exhibited more balanced μe/μh ratios (1.31 and 0.85), but with slightly enhanced short‐current circuit density (JSC) and reduced AVT (23–24%), mainly owing to unavoidable absorption of third component in the visible region. Our conclusion in this work was that the little A‐D‐A non‐fullerene acceptor could improve ternary blend film morphology and charge transport channels and enhanced JSC and PCE, and PM6:Y6:IHIC (20%) with high AVT over 27% and PCE over 12% was more suitable in ST‐PSCs than PM6:Y6:ITIC/IT‐4F (20%). The ternary polymer solar cells demonstrate more balanced charge transport properties based on 20% third component, which improves blend film morphology and charge transport channels, where the ternary system with high average visible transmittance over 27% and power conversation efficiency over 12% is more suitable in ternary semitransparent devices than others.