Energy Transport in CsPbBr3 Perovskite Nanocrystal Solids

Artificial solids of CsPbX 3 perovskite nanocrystals (NC) are well known for their promising charge transport characteristics. The long-range diffusion of photoinduced charges in these materials is attributed to the unique electronic structure of CsPbX 3 NCs associated with high defect tolerance and a low disorder of excited-state energies. Here, we show that the same set of electronic properties allows CsPbBr 3 NC solids to act as superior energy transport materials, which support a long-range diffusion of electrically neutral excitons. By performing time-resolved bulk quenching measurements on halide-treated CsPbBr 3 NC films, we observed average exciton diffusion lengths of 52 and 71 nm for I – - and Cl – -treated solids, respectively. Steady-state fluorescence quenching studies have been employed to explain such a large diffusion length as due to a high defect tolerance and a low disorder of exciton energies in CsPbBr 3 NC solids. We expect that the demonstrated ability of halide-treated CsPbBr 3 NC solids to support a long-range exciton transport could be beneficial for applications in light energy concentration, as was demonstrated in this work through energy transfer measurements in assemblies of perovskite NC donors and CdSe quantum dot acceptors.