Ternary polymer solar cells with iridium-based polymer PM6Ir1 as a donor and N3:ITIC-Th as an acceptor exhibiting over 17.2% efficiency

Abstract

Iridium-based polymer PM6Ir1 as an electron donor and two nonfullerene materials N₃ and ITIC-Th as electron acceptors were selected to prepare efficient polymer solar cells (PSCs). ITIC-Th was used as the third component to enhance photon harvesting and as a morphology regulator to optimize molecular arrangement and phase separation in the ternary active layer. Improvements in open circuit voltage (0.86 V vs. 0.84 V), short circuit current density (26.53 mA cm⁻²vs. 26.13 mA cm⁻²) and fill factor (75.47% vs. 74.11%) are simultaneously obtained for the PSCs with 10 wt% ITIC-Th in the acceptor mixture, leading to a power conversion efficiency (PCE) enhancement from 16.27% to 17.22%. The charge mobility and charge transport balance in the ternary active layer can be enhanced by incorporating ITIC-Th, resulting from the optimized phase separation and molecular arrangement with ITIC-Th as a morphology regulator. The positive effect of ITIC-Th incorporation on PCE improvement can be demonstrated by the relatively high external quantum efficiency values of the optimal ternary PSCs in the spectral range from 300 to 820 nm.