Resonance Energy Transfer from Monolayer WS₂ to Organic Dye Molecules: Conversion of Faint Visible‐Red into Bright Near‐Infrared Luminescence

Abstract

The synergetic combination of transition metal dichalcogenides (TMDCs) with organic dye molecules in functional heterostructures is promising for various optoelectronic applications. Here resonance energy transfer (RET) from a red‐emitting WS2 monolayer (1L‐WS2) to a layer of near‐infrared (NIR) emitting organic dye molecules is demonstrated. It is found that the total photoluminescence (PL) yield of the heterostructures is up to a factor of eight higher as compared to the PL yield of pristine 1L‐WS2. This is attributed to the efficient conversion of the mostly non‐radiative excitons in 1L‐WS2 into radiative excitons in the dye layer. A type‐I energy level alignment of the 1L‐WS2/dye interface assures the emission of bright PL. From excitation density‐dependent PL experiments, it is concluded that RET prevails against defect‐assisted non‐radiative recombination as well as Auger‐type exciton‐exciton annihilation in 1L‐WS2. The work paves the way for employing organic dye molecules in heterostructures with TMDCs in nanoscale light‐emitting devices with improved efficiency and tunable color.

van der Waals 2D transition metal dichalcogenide/organic hybridized heterostructures: recent breakthroughs and emerging prospects of the device

“…14,139 Further, resonance energy transfer (RET) from a red-emitting WS 2 monolayer (1L-WS 2 ) to a layer of near-infrared (NIR)emitting organic dye molecule-based type I heterostructures is demonstrated. 29 It is found that the total PL yield of the heterostructures is up to a factor of eight higher than the PL yield of pristine 1L-WS 2 . They have explained that the efficient RET alone is necessary but not sufficient for the desired PL enhancement.…”

“…For example, a resonance energy transfer (RET) from a red-emitting monolayer WS 2 (1L-WS 2 ) to a layer of NIR-emitting organic dye molecule–based type-I heterostructure. 29 It is found that the total PL yield of the heterostructures is up to a factor of eight higher than the PL yield of pristine 1L-WS 2 . A strong decrease in the PL of the dye is observed on 2L-WS 2 when it gives the type II heterostructure.…”