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Abstract：
Metallic-phase transition metal dichalcogenide quantum dots (TMDs-mQDs) have been reported in recent years. However, a dominant mechanism for modulating their intrinsic exciton behaviors has not been determined yet as their size is close to the Bohr radius. Herein, we demonstrate that the oxidation effect prevails over quantum confinement on metallic-phase tungsten dichalcogenide QDs (WX2-mQDs; X = S, Se) when the QD size becomes larger than the exciton Bohr radius. WX2-mQDs with a diameter of ~12 nm show an obvious change in their photophysical properties when the pH of the solution changes from 2 to 11 compared to changing the size from ~3 nm. Meanwhile, we found that quantum confinement is the dominant function for the optical spectroscopic results in the WX2-mQDs with a size of ~3 nm. This is because the oxidation of the larger WX2-mQDs induces sub-energy states, thus enabling excitons to migrate into the lower defect energy states, whereas in WX2-mQDs with a size comparable to the exciton Bohr radius, protonation enhances the quantum confinement.
摘要：
近年来已经报道了金属相变金属二硫属化物量子点(TMDs-mQDs)。然而,尚未确定调节其固有激子行为的主要机制，因为它们的大小接近玻尔半径。在这里，我们证明了氧化效应在金属相二硫属钨量子点(WX2-mQDs;X=S，Se）当QD尺寸变得大于激子玻尔半径时。直径为〜12nm的WX2-mQD在溶液的pH从2变化到11时，与尺寸从〜3nm变化相比，它们的光物理性质表现出明显的变化。同时,我们发现量子限制是尺寸为〜3nm的WX2-mQDs光谱结果的主要功能。这是因为较大的WX2-mQD的氧化会引起亚能量状态，从而使激子迁移到较低的缺陷能态，而在大小与激子玻尔半径相当的WX2-mQD中，质子化增强了量子限制。
