Well-regulated structure-featuring giant-molecule acceptors enable long-term stability and high-performance binary organic solar cells†

Abstract

Well-defined structure-featuring giant-molecule acceptors (GMAs) can exhibit unique properties of small-molecule acceptors and polymers simultaneously, and the consecutive innovations in materials design have enabled GMA-based organic solar cells (OSCs) to exhibit outstanding device power conversion efficiency (PCE) over 19% and extended long-term stability. Here, through systematically selecting the numbers and positions of the selenium atom, π-spacer linking units and the outermost conjugate ring of the central core of monomers, four novel GMAs are successfully synthesized, GMA-SSS, GMA-SSeS, GMA-SeSSe and GMA-SeSeSe. Surprisingly, the PM6:GMA-SSeS-based OSC yields the highest PCE of 19.37% with a remarkable open current voltage of 0.917 V with reduced voltage loss (ΔE₃ = 0.246 eV) and excellent fill factor of 77.12%. Furthermore, when devices were annealed at 100 °C, the PM6:GMA-SSeS and PM6:GMA-SSS-based OSCs exhibited remarkably extended t_80% lifetimes of 5600 and 5250 h, respectively. Our work indicates that the selenium substituted regulation of linking units and monomers of GMA structures is a valuable approach to obtain devices with high-performance and long-term stability at the same time, shedding light on the further development of GMA-based OSCs.