Graphene Quantum Dots Tuning the Photoluminescence of MoS2Monolayers

AUG . 31 2015
Peking University, Aug. 30, 2015: Low-dimensional materials have attracted a wide spread attention due to their unique electronic and structural properties for new physical phenomena. MoS2 monolayers are a kind of two-dimensional materials, which have been a hot research topic in materials area. Recently, Prof. Fang Zheyu, school of physics, Peking University has successfully realized an effective doping and active pholuminescence (PL) tuning of MoS2monolayers by utilizing localized plasmons of graphene quantum dots (GQDs). The work was published as on line first in Advanced Materials (Adv. Mater., 2015, doi: 10.1002/adma.201501888).

Schematic view of charge transfer process in GQD/MoS2 heterostructures and active tuning of MoS2 pholuminescence
MoS2 monolayer is atomical thickness direct band-gap semiconductor with extremely high PL efficiency. The recombination of exciton and charge exciton (trion) can be modulated by GQDs doping which results in the redshifting of MoS2 PL peaks. Although, several methods have been achieved in doping MoS2, including gate bias tuning, chemical molecule interacting. However, the low doping efficiency and passive control make the opto-electronic application difficult for the future. Prof. Fang and his group designed GQD/MoS2 heterostructures and realized an effective and active controlled optical doping process. The doping effect is induced by the charge tunneling of localized surface plasmon of GQDs. GQDs doping effect was further used to modulate the degree of circular polarization of MoS2 monolayers. The experimental phenomena were characterized and proved by Raman and PL measurement. This work has demonstrated the charge transfer process at the interface between quantum dots and two-dimensional materials, which paves the way of applications based on low-dimensional heterostructures in biological sensing and electronic devices.
In recent years, Prof. Fang’s group has achieved a series of research results in the field of surface plasmons with low-dimensional materials. Such as plasmonic hot electrons induced phase transition of MoS2 (Adv. Mater. 2014), localized plasmons of graphene nanostructure (Nano Lett2014ACS Nano2013), enhanced photodetection based on graphene-nanoantenna (Nano Lett, 2012), optical controlled doping of graphene (ACS Nano, 2012) and surface plasmons enhanced photocatalysis (Nano Lett, 2013Adv. Mater., 2013) .
Li Ziwei as the first author of this publication, is the Ph.D. student in school of physics of Peking University. Prof. James Tour in Rice University (USA) prepared GQDs samples for the experiment. This work is supported by National Basic Research Program of China (973 Program), National Natural Science Foundation of China, Beijing Natural Science Foundation and National Excellent Doctoral Dissertation Fundation.
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Source: School of Physics

Edited by: Zhang Jiang