Ternary polymer solar cells achieving 11.78% efficiency with two fluorinated non-fullerene acceptors

摘要

Polymer solar cells (PSCs) were fabricated with PTB7-Th as donor and fluorinated non-fullerene materials IEICO-4F, IT-4F or their mixture as acceptor. Binary PSCs with IEICO-4F or IT-4F as acceptor exhibit a power conversion efficiency (PCE) of 10.74% or 8.81% and fill factor (FF) of 63.32% or 73.90%, respectively. The PCE of 11.78% is achieved for the optimized ternary PSCs with 25 wt% IT-4F in acceptors, resulting from over 12.3% FF improvement (71.12% vs 63.32%). The distinguished FF improvement should be attributed to the optimized molecular arrangement and phase separation scale by incorporating the third component as morphology regulator. This work provides an efficient strategy on selecting materials for achieving efficient ternary PSCs by combining the superior photovoltaic parameters of two corresponding binary PSCs, in addition to the used materials with complementary absorption spectra.