The alloy donor strategy leverages both complementary polymer donors to enable highly efficient and stable ternary organic solar cells

Abstract

With the rapid development of ternary organic photovoltaics (OPVs), exploring highly efficient matching ternary components has become a key issue. Herein, a ternary OPV was fabricated using J71 and PBDTTS-2FQx as donors and IT-4F as the acceptor. Binary devices based on J71:IT-4F and PBDTTS-2FQx:IT-4F achieved power conversion efficiencies (PCEs) of 9.52% and 6.44%, respectively. By leveraging the advantages of the two systems, a ternary OPV incorporating both donors was successfully prepared. With a weight ratio of J71:PBDTTS-2FQx:IT-4F of 0.85 : 0.15 : 1, the ternary OPV achieved an optimum PCE of 11.23%, along with improved short-circuit current density (J_SC) and fill factor (FF). Moreover, the ternary OPVs exhibited substantially enhanced stability relative to the binary ones. The unencapsulated J71:IT-4F OPV retained 80% of its initial PCE after 530 h, while the unencapsulated ternary OPV retained 80% efficiency after 1000 h. This enhanced stability arises from the good compatibility between J71 and PBDTTS-2FQx, which facilitates the formation of an alloy-like donor phase.