Ternary Blend Organic Photovoltaics with High Efficiency and Stability Through Energy Transfer and Molecular Packing Induced by an A-D-A Small Molecule.

A novel A-D-A type small molecule (DTP-2EH-IO2Cl) incorporating dithiophenepyrrole (DTP) core with indene-dione (IO2Cl) side chain with an intermediate band gap and rigid structure is incorporated into polymer donor PM6 and one of the three A-DA'D-A small molecule acceptor-L8-BO, BTP-eC9 or Y6-for ternary-blend organic photovoltaics (OPVs). The third component DTP-2EH-IO2Cl induces not only energy transfer but also stronger molecular packing of the acceptors, resulting in a larger coherence length and enhanced absorption that enhances devices' power conversion efficiencies (PCE) and thermal stability. The PCE values of the champion ternary-blend devices PM6:L8-BO, PM6:BTP-eC9, and PM6:Y6 incorporating DTP-2EH-IO2Cl are 19.