Ternary Organic Blend Approaches for High Photovoltaic Performance in Versatile Applications

Ternary blend approaches are demonstrated as a universal means to improve overall performance of organic photovoltaics (OPVs) in both indoor and outdoor conditions. A comparative study on two donors:one acceptor (2D:1A) and one donor:two acceptors (1D:2A) ternary blends shows that both approaches are universally effective for indoor and outdoor operation; the 1D:2A devices incorporating a nonfullerene acceptor (NFA) benefit from less charge recombination and higher power conversion efficiencies (PCEs) for various irradiation conditions, while the performance of the 2D:1A blends depends on the emission spectrum of the incident light source. The synergistic merits of NFAs and ternary structure in the 1D:2A ternary OPVs secure better performance and generality regardless of the incident lighting. A combination of experimental and theoretical analyses unveils that NFAs optimize packing and arrangement of molecules to build efficient cascade ternary junctions in the 1D:2A blends, which can be important design guidelines for the third component in ternary OPVs. The optimized 1D:2A ternary OPV exhibits a new record PCE of 25.6% under a 200 lux light-emitting diode (LED) and 26.4% under a 1000 lux LED, and superior durability under industrial relevant thermal stress, suggesting new opportunities in diverse practical applications challenging the currently dominant PV technologies.