An acceptor with an asymmetric and extended conjugated backbone for high-efficiency organic solar cells with low nonradiative energy loss

Abstract

One of the significant factors that limit efficiencies of organic solar cells (OSCs) is their large energy loss (E_loss), especially the high nonradiative recombination energy loss (ΔE_nr). Herein, an acceptor named NQF with an asymmetric and extended conjugation central core has been designed and synthesized. Compared with Y6, NQF exhibits upshifted HOMO and LUMO energy levels and a higher photoluminescence quantum yield (PLQY). The OSC based on PM6:NQF demonstrates a ΔE_nr as low as 0.177 eV and thus a high power conversion efficiency (PCE) of 17.57%. In contrast, the control device PM6:Y6 gives a PCE of 16.45% with a ΔE_nr value of 0.231 eV. This work achieves molecular design with low ΔE_nr and demonstrates that the E_loss of OSCs can be effectively reduced through rational and delicate molecular design.