Unveiling the degradation process of monolayer WSe2 with aging

Abstract

We present an effective protocol for extracting localization energy from WSe2 monolayers, based on temperature-dependent spectral variation of photoluminescence (PL), and observe time-sequential changes over a long period of time. We found that even freshly exfoliated WSe2 exhibits deviation from the Varshni formula upon exposure to air, while the temperature-dependent PL lineshapes of h-BN encapsulated WSe2 match well with delocalized features for as long as two years of the aging period. Our findings support the prospect of h-BN encapsulation for monoatomic transition metal dichalcogenides to meet the longevity condition, which is a prerequisite for practical components in the electronics industry.