Symmetric and asymmetric non-fullerene acceptors cooperate synergistically for ternary optoelectronic devices

Abstract

We report two new asymmetric non-fullerene acceptors, A-YBO-2F and A-YBO-2Cl, as third components in organic solar cells (OSCs) and organic photodetectors (OPDs). These asymmetric D-A acceptors, with one terminal group removed based on a same π-conjugated backbone, exhibit blue-shifted complementary absorption and shallower energy levels compared to symmetric A-D-A acceptors (Y6). Additionally, they show good miscibility with the A-D-A type Y6, forming an alloy-like phase with Y6 that features an elevated conduction band and enhanced molecular packing through stronger dipole–dipole interactions. This leads to significant improvement in the photoelectrical characteristics of OSCs and reduced dark current in OPDs. As a result, the ternary OSC with A-YBO-2Cl achieves a power conversion efficiency of 18.37 %, surpassing the 16.95 % of the binary device. Additionally, the ternary OPD with A-YBO-2Cl shows a significantly lower dark current density of 1.06 pA cm⁻² at V → 0 V and a higher specific detectivity of 6.14 × 10¹² Jones at 808 nm compared to its binary counterpart. These findings demonstrate that combining asymmetric D-A and symmetric A-D-A acceptors with a same conjugated framework effectively controls miscibility, energy levels, morphology, and performance in both OSCs and OPDs, offering a promising strategy for advancing organic semiconductor technology.