Evolutional Photoluminescence Property in Ultraviolet-ozone-treated Monolayer MoS2

Abstract Two-dimensional (2D) semiconductors offer significant advantages for electronic and optoelectronic devices. It is essential to develop the ability to dynamically manipulate and control their physical properties by simple ways for promoting practical applications. Herein, we demonstrate that a simple ultraviolet-ozone (UVO) treatment can bring dynamical properties and additional functions to monolayer MoS2, as revealed by the time-dependent photoluminescence (PL) behavior. The PL behavior can be flexibly tuned by UVO treatment time, laser irradiation power and storing time in the air, originating from the nonequilibrium adsorption/desorption process of O2 molecules on the surface of MoS2. Combined the analysis of material characterizations and theoretical calculations, UVO treatment causes high-density O2 molecules to physically bond with MoS2 and thus the direct-indirect bandgap transition, resulting in a strong PL quenching. This metastable O2 adsorption, which can be easily broken and artificially regulated, further enables an evolutionary, reversible and controllable PL behavior. Moreover, the PL of MoS2 covered by mask made of patterned 2D materials exhibits graphical evolution and emission switch behavior, offering new possibilities in information storage and security devices.