Reduced dielectric screening and enhanced energy transfer in single and few-layer MoS2

TL;DR

This study demonstrates highly efficient non-radiative energy transfer from quantum dots to monolayer and few-layer MoS2, with efficiency increasing as MoS2 thickness decreases due to reduced dielectric screening, enabling various optoelectronic applications.

Contribution

It reveals the counterintuitive enhancement of energy transfer efficiency in thinner MoS2 layers caused by reduced dielectric screening, which was not previously understood.

Findings

Energy transfer efficiency exceeds 95% for monolayer MoS2

Efficiency increases as MoS2 layer thickness decreases

Reduced dielectric screening enhances energy transfer in 2D materials

Abstract

We report highly efficient non-radiative energy transfer from cadmium selenide (CdSe) quantum dots to monolayer and few-layer molybdenum disulfide (MoS2). The quenching of the donor quantum dot photoluminescence increases as the MoS2 flake thickness decreases, with the highest efficiency (>95%) observed for monolayer MoS2. This counterintuitive result arises from reduced dielectric screening in thin layer semiconductors having unusually large permittivity and a strong in-plane transition dipole moment, as found in MoS2. Excitonic energy transfer between a 0D emitter and a 2D absorber is fundamentally interesting and enables a wide range of applications including broadband optical down-conversion, optical detection, photovoltaic sensitization, and color shifting in light-emitting devices.