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General Oxidative Chemical Activation of Neutral Exciton Emission in Colloidal MoS2 Monolayers
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DOI:10.1021/jacs.6c07304.png)
Abstract
En 中文
Colloidal two-dimensional semiconductors are promising for scalable optoelectronics, but their development has been fundamentally limited by defect-induced nonradiative recombination that suppresses exciton emission. In particular, sulfur vacancies in solution-processed MoS2 introduce charge doping and trap states that favor trion formation, preventing bright neutral exciton photoluminescence. Here we show that simple oxidative chemistry activates bright neutral exciton emission in colloidal MoS2 monolayers. Ultraviolet (UV) irradiation under ambient conditions enhances photoluminescence by over 2 orders of magnitude, accompanied by a pronounced blueshift and a ∼100-fold increase in exciton lifetime (0.07 to 6.14 ns), indicating a transition from trion-dominated to neutral exciton recombination. We identify UV-driven oxygen reduction as the key process that passivates sulfur vacancies and induces electron dedoping effect, thereby suppressing nonradiative decay pathways. This mechanism is general: a range of oxidants, including H2O2, (NH4)2S2O8, (NH4)2Ce(NO3)6, and NaIO4, rapidly activate emission, in some cases without UV irradiation. These findings establish a chemically tunable strategy for controlling excitonic emission in solution-dispersed MoS2, enabling scalable optoelectronic and photonic applications.
Journal
IF:
15.6
Papers:
20.0W
Citations:
60.2W
