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Unveiling Bandgap Evolution and Carrier Redistribution in Multilayer WSe 2 : Enhanced Photon Emission via Heat Engineering
Author(s) -
Li Yuanzheng,
Liu Weizhen,
Xu Haiyang,
Chen Heyu,
Ren Hang,
Shi Jia,
Du Wenna,
Zhang Wei,
Feng Qiushi,
Yan Jiaxu,
Zhang Cen,
Liu Yichun,
Liu Xinfeng
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201901226
Subject(s) - materials science , photoluminescence , redistribution (election) , band gap , optoelectronics , photon , semiconductor , thermal conduction , conduction band , optics , electron , physics , politics , political science , law , composite material , quantum mechanics
Abstract Manipulating the bandgap structure and carrier distribution of multilayer transition metal dichalcogenides (TMDs) is crucial for improving their fluorescence efficiency and extending their optoelectronic applications. Herein, the evolution of the conduction band minimum of multilayer WSe 2 as a function of the temperature and thickness is experimentally demonstrated and an ≈70‐fold fluorescence enhancement of the K–K direct emission is observed at 560 K in multilayer WSe 2 flakes (≈170 nm) by heat engineering. This abnormal enhancement is attributed to thermally driven carrier redistribution achieved via intervalley transfer, which is confirmed by the theoretical calculations and temperature‐dependent time‐resolved photoluminescence. In addition, a threshold temperature of the intervalley transfer is proposed to describe the on‐state of the carrier redistribution model. The corresponding threshold temperature is determined to be ≈580 K, which is consistent with the temperature at which the maximum photoluminescence enhancement is observed. The study provides a useful strategy to optimize the optical and electric performances of multilayer WSe 2 and other TMDs materials.