The Confinement and Migration of Charge-Carriers in Lead Halide Perovskites

Abstract

With the growing success of halide perovskites as functional materials in solar cells, LEDs, and lasers, studies are progressing to reveal their optical and charge-carrier properties. This chapter describes the consequences of charge-carrier generation, stabilization, and recombination in perovskite nanocrystals, quantum dots, and their assemblies. The strong confinement of charge-carriers in perovskite quantum dots causes photoluminescence blinking with distinct ON and OFF events, which is due to photocharging and ultrafast Auger nonradiative recombination. Such a blinking with long OFF periods suppresses superoxide generation and oxidation of perovskites. When perovskite nanocrystals and quantum dots are closely-packed into superlattices, the carrier confinement is broken due to the narrowing of inter-particle energy levels and the formation of minibands that allow for carrier migration. This results in unexpectedly delayed photoluminescence at low intensities of excitation light, whereas at high intensities of excitation light, the ultrafast radiative recombination of charge-carriers occurs. These properties of quantum dots, nanocrystals, and assemblies of perovskites are important to be considered during the construction of devices such as solar cells, LEDs, and lasers.