Lateral transport and dynamical behavior of quasi-two-dimensional excitons at high density along a stacking disorder plane in layered BiI 3 crystals

Abstract

Macroscopic exciton transport phenomena from a small area of an exciting laser spot to outside the spot along a quasi-two-dimensional planar defect in BiI 3, are presented from space-resolved pump-probe absorption, photoluminescence, and four-wave-mixing measurements. At high intensity, the blue shift of the transition energy at the point away from the pump spot is analyzed by the 2-D diffusion. The four-wave-mixing signals are detected with time delays when the two laser beams are spatially separated.