Origins of the long-range exciton diffusion in perovskite nanocrystal films: photon recycling vs exciton hopping

Abstract

Exciton hopping: Energy travels far in perovskite nanocrystal films Excitons quasi-particles in methylammonium lead bromide perovskite nanocrystal films can travel over a surprisingly long distance. Tze Chien Sum and colleagues at Singapore’s Nanyang Technological University uncovered that the long diffusion lengths of more than one micrometer are largely due to excitons hopping from one nanocrystal to another. They are also caused, albeit to a lesser degree, by photon recycling, in which absorbed photons are re-emitted within the material, generating more charge carriers. The team found that perovskite nanocrystals connected by octylamine ligands showed the longest exciton hopping range compared to those connected by hexylamine or oleylamine ligands. The findings demonstrate the potential of lead halide perovskite nanocrystal films for fabricating smaller, faster, and more energy-efficient electronic devices. They also improve the basic understanding of the mechanisms behind long-range energy transport in these films.