采用机械剥离法在金刚石对顶砧中制备了单层WSe2和MoSe2样品, 利用高压微区荧光光谱测量技术, 在氩传压介质环境下对其激子发光行为进行了高压调控研究。其中单层WSe2的中性和负电激子演化趋势在2.43 GPa处出现拐点, 单层MoSe2中性激子发光在3.7 GPa处发生了劈裂。结合第一性原理计算分析, 确认该不连续现象的产生机制为压力诱导的导带底K-Λ交互转变。该结果可以扩大至整个二维层状材料体系, 为发展激子器件垫定基础。

Monolayer MoSe2 and WSe2 samples were prepared by mechanical exfoliation in diamond anvil cell(DAC). The high-pressure micro-area fluorescence spectroscopy technique was used to study excitons emission behavior under pressure in argon pressure-transmitting medium(PTM). The neutral and negative exciton evolutionary trends of monolayer WSe2 showed an inflection point at 2.43 GPa, and the neutral exciton emission of monolayer MoSe2 appeared a new split peak at 3.7 GPa. Combined with the first-principles calculation and analysis, we confirmed that the mechanism of these discontinuities is the pressure-induced conduction band bottom K-Λ crossover. This result can be extended to the entire two-dimensional layered material family, and laying foundation for the development of exciton devices.