Dominating Interlayer Resonant Energy Transfer in Type-II 2D Heterostructure

TL;DR

This paper demonstrates that in certain type-II 2D heterostructures, nonradiative energy transfer can dominate over charge transfer, significantly enhancing photoluminescence, which offers new ways to improve optoelectronic device efficiency.

Contribution

It reveals that nonradiative energy transfer can dominate in type-II TMD heterostructures, providing a novel approach to enhance PL quantum yield by material selection.

Findings

ReS2 to MoSe2 energy transfer dominates over charge transfer.

Over 3.6 times PL enhancement without charge-blocking layer.

More than tenfold PL increase with charge-blocking layer.

Abstract

Type-II heterostructures (HSs) are essential components of modern electronic and optoelectronic devices. Earlier studies have found that in type-II transition metal dichalcogenide (TMD) HSs, the dominating carrier relaxation pathway is the interlayer charge transfer (CT) mechanism. Here, this report shows that, in a type-II HS formed between monolayers of MoSe2 and ReS2, nonradiative energy transfer (ET) from higher to lower work function material (ReS2 to MoSe2) dominates over the traditional CT process with and without a charge-blocking interlayer. Without a charge-blocking interlayer, the HS area shows 3.6 times MoSe2 photoluminescence (PL) enhancement as compared to the MoSe2 area alone. After completely blocking the CT process, more than one order of magnitude higher MoSe2 PL emission was achieved from the HS area. This work reveals that the nature of this ET is truly a resonant effect by showing that in a similar type-II HS formed by ReS2 and WSe2, CT dominates over ET, resulting in a severely quenched WSe2 PL. This study not only provides significant insight into the competing interlayer processes, but also shows an innovative way to increase the PL quantum yield of the desired TMD material using ET process by carefully choosing the right material combination for HS.