Complex diffusion-based kinetics of photoluminescence in semiconductor nanoplatelets

TL;DR

This paper develops a diffusion-based model to explain the photoluminescence behavior in semiconductor nanoplatelets, capturing the transition from recombination-dominated to trap-release-dominated emission over time.

Contribution

It introduces a novel diffusion-based simulation and theoretical framework that accurately reproduces experimental PL curves in semiconductor nanoplatelets.

Findings

PL intensity exhibits exponential decay at short times due to recombination.

Long-time PL decay follows a power-law tail from exciton release from surface traps.

Diffusivity controls the crossover between recombination and trapping regimes.

Abstract

We present a diffusion-based simulation and theoretical models for explanation of photoluminescence (PL) emission intensity in semiconductor nanoplatelets. It is shown that the shape of PL intensity curves can be reproduced by the interplay of recombination, diffusion and trapping of excitons. The emission intensity at short times is purely exponential and is defined by recombination. At long times it is governed by the release of excitons from surface traps and is characterized by a power-law tail. We show that the crossover from one limit to another is controlled by diffusion properties. This intermediate region exhibits a rich behaviour depending on the value of diffusivity. Proposed approach reproduces all the features of experimental curves measured for different nanoplatelet systems.