Exploring ternary organic photovoltaics for the reduced nonradiative recombination and improved efficiency over 17.23% with a simple large-bandgap small molecular third component

Ternary strategy is one of the most effective methods to further boost the power conversion efficiency (PCE) of organic photovoltaic cells (OPVs). In terms of high-efficiency PM6:Y6 binary systems, there is still room to further reduce energy loss (E_loss) through regulating molecular packing and aggregation by introducing a third component in the construction of ternary OPVs. Here we introduce a simple molecule BR1 based on an acceptor-donor-acceptor (A-D-A) structure with a wide bandgap and high crystallinity into PM6:Y6-based OPVs. It is proved that BR1 can be selectively dispersed into the donor phase in the PM6:Y6 and reduce disorder in the ternary blends, thus resulting in lower E_loss,non-rad and E_loss. Furthermore, the mechanism study reveals well-develop phase separation morphology and complemented absorption spectra in the ternary blends, leading to higher charge mobility, suppressed recombination, which concurrently contributes to the significantly improved PCE of 17.23% for the ternary system compared with the binary ones (16.21%). This work provides an effective approach to improve the performance of the PM6:Y6-based OPVs by adopting a ternary strategy with a simple molecule as the third component.