Selective Chemical Modulation of Interlayer Excitons in Atomically Thin Heterostructures.

Ji, Jaehoon; Delehey, Charles M; Houpt, Duncan N; Heighway, Mathew K; Lee, Tonghun; Choi, Jong Hyun · Nano Lett · 2020

basic_science · Level V

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Abstract

Strongly bound interlayer excitons (X<sub>I</sub>s) in atomically thin transition metal dichalcogenide (TMDC) heterostructures such as MoS<sub>2</sub>/WSe<sub>2</sub> show promising optoelectronic properties for spin-valleytronics and excitonic devices. The ability to probe and control X<sub>I</sub>s is critical for the development of such applications. This Letter introduces a versatile chemical method for selectively tailoring interlayer excitons in TMDC heterostructures. We show that two organic layers form uniform layers on a WSe<sub>2</sub>/MoS<sub>2</sub> heterostructure and that the X<sub>I</sub> photoluminescence may be either preserved or quenched. The interlayer emission can also be modulated differently by the formation of the organic layer on either side of the TMDC/TMDC heterostructure. We find that the resulting interlayer emission is dominated by selective photoinduced charge transfer over dark-state p-doping effects. These results shed critical insights on interlayer excitons at the TMDC/TMDC heterointerfaces and provide a versatile approach for selectively tailoring them for optoelectronic applications.