High-performance pseudo-bilayer ternary organic solar cells with PC71BM as the third component

Abstract

Optimizing active layer morphology and broadening spectrum utilization range are important methods to improve the performance of organic solar cells. In this study, PM6/Y6:PC₇₁BM pseudo-bilayer ternary organic solar cells were prepared with a layer-by-layer sequential deposition method. The introduction of the fullerene derivative PC₇₁BM as the third component into the PM6/Y6 binary system improves light absorption and boosts the open-circuit voltage. PC₇₁BM works as a morphology regulator to facilitate Y6 diffusion into the PM6 layer and increase the contact interface between the PM6 layer and Y6 layer, which enhances exciton dissociation probability and provides a cascade energy level alignment for efficient charge transport. The independent carrier transport channels provided by the pseudo-bilayer planar heterojunction improve charge transport performance and inhibit carrier recombination. The comprehensive utilization of fullerene and non-fullerene acceptors, the combination of the pseudo-bilayer planar heterojunction and the ternary strategy synergistically boost the power conversion efficiency from 16.44% for the PM6/Y6 binary device to 17.82% for the PM6/Y6:PC₇₁BM device, and the PM6/Y6:PC₇₁BM pseudo-bilayer ternary device exhibits better stability. Pseudo-bilayer ternary planar heterojunction is a promising device structure to achieve high performance organic solar cells for potential commercial applications.