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Metallic phase transition metal dichalcogenide quantum dots showing di…

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논문명 Metallic phase transition metal dichalcogenide quantum dots showing different optical charge excitation and decay pathways
저자 Bo-Hyun Kim, Min-Ho Jang, Hyewon Yoon, Hyun Jun Kim, Yong-Hoon Cho, Seokwoo Jeon and Sung-Ho Song
저널명 NPG Asia Materials
게재년월 2021/4/23
Vol. pp

The charge excitation and decay pathways of two-dimensional heteroatomic quantum dots (QDs) are affected by the quantum confinement effect, bandgap structure and strong exciton binding energy. Recently, semiconducting transition metal dichalcogenides (TMDs) have been intensively studied; however, the charge dynamics of metallic phase QDs (mQDs) of TMDs remain relatively unknown. Herein, we investigate the photophysical properties of TMDmQDs of two sizes, where the TMD-mQDs show different charge excitation and decay pathways that are mainly ascribed to the defect states and valence band splitting, resulting in a large Stokes shift and two excitation bands for maximum photoluminescence (PL). Interestingly, the dominant excitation band redshifts as the size increases, and the time-resolved PL peak redshifts at an excitation wavelength of 266 nm in the smaller QDs. Additionally, the lifetime is shortened in the larger QDs. From the structural and theoretical analysis, we discuss that the charge decay pathway in the smaller QDs is predominantly affected by edge oxidation, whereas the vacancies play an important role in the larger QDs.