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A High‐Efficiency Wavelength‐Tunable Monolayer LED with Hybrid Continuous‐Pulsed Injection
Author(s) -
Zhu Yi,
Wang Bowen,
Li Ziyuan,
Zhang Jian,
Tang Yilin,
Torres Juan F.,
Lipiński Wojciech,
Fu Lan,
Lu Yuerui
Publication year - 2021
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202101375
Subject(s) - materials science , trion , optoelectronics , monolayer , electroluminescence , exciton , wavelength , diode , light emitting diode , quantum efficiency , light emission , semiconductor , quantum dot , nanotechnology , layer (electronics) , physics , quantum mechanics
High‐efficiency and wavelength‐tunable light‐emitting diode (LED) devices will play an important role in future advanced optoelectronic systems. Traditional semiconductor LED devices typically have a fixed emission wavelength that is determined by the energy of the emission states. Here, a novel high‐efficiency and wavelength‐tunable monolayer WS 2 LED device, which operates in the hybrid mode of continuous‐pulsed injection, is developed. This hybrid injection enables highly enhanced emission efficiency (>20 times) and effective size of emission area (>5 times) at room temperature. The emission wavelength of the WS 2 monolayer LED device can be tuned over more than 40 nm by driving AC voltages, from exciton emission to trion emission, and further to defect emission. The quantum efficiency of defect electroluminescence (EL) emission is measured to be more than 24.5 times larger than that from free exciton and trion EL emission. The separate carrier injection in the LED also demonstrates advantages in allowing defect species to be visualized and distinguished in real space. Those defects are assigned to be negatively charged defects. The results open a new route to develop high‐performance and wavelength‐tunable LED devices for future advanced optoelectronic applications.