Double-dipole bi-tetraphenylphosphonium bromide exhibits excellent cathode modification effect for organic solar cell, HOMO level down to −7.32 eV.

Abstract

Nowadays, amine containing electrode interface material destroy the non-fullerene acceptor becomes a hard nut to crack for organic solar cells. Developing water-soluble interface material which is no chemical reaction with non-fullerene acceptor is an important research theme. Here, we report two bi-triangular pyramidal electronic configuration organic-phosphonium bromides as non-amine cathode interfacial layer for fabricating high-efficiency stable organic solar cells. The power conversion efficiency (PCE) of inverted device structure with PBDB-T/ITIC as active layer is up to 11.58 % which is great larger than control device PCE (9.35 %). Same device structure with PM6/Y6 as active layer, the PCE is up to 15.26 % and also is dramatically higher than the referred device PCE 14.36 %. Meanwhile, the devices show greatly improved stability by organic-phosphonium bromide interlayer.