Energy Transfer and Photoluminescence Enhancement in WS2/hBN/MoS2 Heterostructures
Two-dimensional(2D)transition metal dichalcogenides(TMDs)and their heterostructures(HSs)exhibit unique optical properties and show great promise for developing next-generation optoelectronics.However,the photo-luminescence(PL)quantum yield of monolayer(1L)TMDs is still quite low at room temperature,which severely lim-its their practical applications.Here we report a PL enhancement effect of 1L WS2 at room temperature when con-structing it into 1L-WS2/hBN/1L-MoS2 vertical HSs.The PL enhancement factors(EFs)can be up to 4.2.By using transient absorption(TA)spectroscopy,we demonstrate that the PL enhancement effect is due to energy transfer from 1L MoS2 to 1L WS2.The energy transfer process occurs on a picosecond timescale and lasts more than one hundred picoseconds which indicates a prominent contribution from exciton-exciton annihilation.Furthermore,the PL en-hancement effect of 1L WS2 can be observed in 2L-MoS2/hBN/1L-WS2 and 3L-MoS2/hBN/1L-WS2 HSs.Our study provides a comprehensive understanding of the energy transfer process in the PL enhancement of 2D TMDs and a fea-sible way to optimize the performance of TMD-based optoelectronic devices.
transition metal dichalcogenidevan der Waals heterostructuresphotoluminescenceFörster resonance energy transferexciton-exciton annihilation
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