Efficient wide-bandgap perovskite solar cells enabled by doping a bromine-rich molecule

Abstract

Wide-bandgap (wide-E-g, similar to 1.7 eV or higher) perovskite solar cells (PSCs) have attracted extensive attention due to the great potential of fabricating high-performance perovskite-based tandem solar cells via combining with low-bandgap absorbers, which is considered promising to exceed the Shockley-Queisser efficiency limit. However, inverted wide-E-g PSCs with a minimized open-circuit voltage (V-oc) loss, which are more suitable to prepare all-perovskite tandem devices, are still lacking study. Here, we report a strategy of adding 1,3,5-tris (bromomethyl) benzene (TBB) into wide-E-g perovskite absorber to passivate the perovskite film, leading to an enhanced average V-oc. Incorporation of TBB prolongs carrier lifetimes in wide-E-g perovskite due to reduction of defects in perovskites and makes a better energy level matching between perovskite absorber and electron transport layer. As a result, we achieve the power conversion efficiency of 17.12% for our inverted TBB-doped PSC with an enhanced V-oc of 1.19 V, compared with that (16.14%) for the control one (1.14 V).