Role of Magnetic Coupling in Photoluminescence Kinetics of Mn2+-doped ZnS Nanoplatelets

TL;DR

This study investigates how magnetic coupling of Mn2+ ions affects the photoluminescence kinetics in Mn2+-doped ZnS nanoplatelets, revealing the influence of dopant location and concentration on optical properties through experiments and simulations.

Contribution

It introduces a combined experimental and theoretical approach to understand Mn2+ doping effects in ZnS nanostructures, highlighting the role of surface ions and coupling regimes.

Findings

Surface Mn2+ ions create emissive states affecting PL.

Suppressed surface contribution reveals intrinsic PL decay mechanisms.

DFT explains double and triple exponential decay behaviors.

Abstract

Mn2+-doped semiconductor nanocrystals with tuned location and concentration of Mn2+ ions can yield diverse coupling regimes, which can highly influence their optical properties such as emission wavelength and photoluminescence (PL) lifetime. However, investigation on the relationship between the Mn2+ concentration and the optical properties is still challenging because of the complex interactions of Mn2+ ions and the host and between the Mn2+ ions. Here, atomically flat ZnS nanoplatelets (NPLs) with uniform thickness were chosen as matrixes for Mn2+ doping. Using time-resolved (TR) PL spectroscopy and density functional theory (DFT) calculations, a connection between coupling and PL kinetics of Mn2+ ions was established. Moreover, it was found that the Mn2+ ions residing on the surface of a nanostructure produce emissive states and interfere with the change of properties by Mn2+/Mn2+ coupling. In a configuration with suppressed surface contribution to the optical response we show the underlying physical reasons for double and triple exponential decay by DFT methods. We believe that the presented doping strategy and simulation methodology of the Mn2+-doped ZnS system is a universal platform to study dopant location- and concentration-dependent properties also in other semiconductors.