The Study Of The Multi-colour Photoluminescence Properties Of Carbon Quantum Dots/Molybdenum Disulfide

Molybdenum disulfide?MoS₂?is a two-dimensional semiconductor material.The monolayer MoS₂ has a direct band gap structure and excellent photoelectric properties because of its unique hexagonal crystal structure.Therefore,it has great potential in the application of optoelectronic devices.Due to the limitation of exciton energy and band structure,the monolayer MoS₂ can only emit narrow band red light.It is difficult to achieve controllable red,green and blue three primary color emission.Therefore,it has been greatly limited in making ultra thin multicolor light-emitting devices.Carbon quantum dots?CQDs?is a newly discovered zero-dimensional?0D?material with high efficient quantum yields and tunable light-emission bands.In general,CQDs shows an efficient PL that can be regulated from blue to green.However,the intensity of PL is weak in the red light range.In this paper,we combined the advantages that monolayer MoS₂ has high efficient emission in red light and CQDs has high efficient emission in blue and green light,and prepared two dimensional/zero dimensional composite luminescent materials using MoS₂ and CQDs.The luminescent properties of the composite system were studied.In the experiment,we adjusted the luminescence of the monolayer MoS₂ by coating an ultrathin and highly efficient CQDs film on the surface of the monolayer MoS₂.These novel 1L-MoS₂/CQDs composited samples have multiple emission bands,including the red band belonging to MoS₂ and the tunable band belonging to CQDs.The balanced intensity of these bands can be obtained by optimizing the thickness of CQDs to about 10 nm.By changing the excitation wavelengths,the emission bands of these 1L-MoS₂/CQDs composites can be adjusted from 550-700 nm to 450-700 nm.The luminescence color can be adjusted from orange?CIE0.5149,0.3766?to yellow green?CIE0.3175,0.4509?,which is much broader than that of the monolayer MoS₂.