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Unveiling Bandgap Evolution and Carrier Redistribution in Multilayer WSe2: Enhanced Photon Emission via Heat Engineering
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2019-12-05 , DOI: 10.1002/adom.201901226
Yuanzheng Li 1, 2 , Weizhen Liu 1 , Haiyang Xu 1 , Heyu Chen 1 , Hang Ren 1 , Jia Shi 2 , Wenna Du 2, 3 , Wei Zhang 1 , Qiushi Feng 1 , Jiaxu Yan 1 , Cen Zhang 1 , Yichun Liu 1 , Xinfeng Liu 2
Affiliation  

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 WSe2 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 WSe2 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 WSe2 and other TMDs materials.

中文翻译:

揭示多层WSe2中的带隙演化和载流子重新分布:通过热工程技术增强的光子发射

操纵多层过渡金属二硫化碳(TMD)的带隙结构和载流子分布对于提高其荧光效率和扩展其光电应用至关重要。在此,实验证明了多层WSe 2的导带最小值随温度和厚度的变化,并且在多层WSe 2中在560 K处观察到K–K直接发射的≈70倍荧光增强片(约170 nm)通过热工程。这种异常的增强归因于通过间隔转移实现的热驱动载流子的重新分布,这通过理论计算和与温度有关的时间分辨光致发光得到了证实。另外,提出了区间传输的阈值温度来描述载波重新分配模型的导通状态。相应的阈值温度确定为≈580K,这与观察到最大光致发光增强的温度一致。该研究为优化多层WSe 2和其他TMDs材料的光学和电性能提供了有用的策略。
更新日期:2020-01-17
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