Electrically Tunable Valley-Light Emitting Diode (vLED) Based on CVD-Grown Monolayer WS2

• Published in: Nano letters Vol. 16; no. 3; pp. 1560 - 1567
• Main Authors: Yang, Weihuang, Shang, Jingzhi, Wang, Jianpu, Shen, Xiaonan, Cao, Bingchen, Peimyoo, Namphung, Zou, Chenji, Chen, Yu, Wang, Yanlong, Cong, Chunxiao, Huang, Wei, Yu, Ting
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.03.2016
• Subjects: 2D semiconductor; valley polarization; light-emitting diode; chiral electroluminescence; chemical vapor deposition; WS2
• DOI: 10.1021/acs.nanolett.5b04066
• ISSN: 1530-6984; 1530-6992

Owing to direct band gap and strong spin–orbit coupling, monolayer transition-metal dichalcogenides (TMDs) exhibit rich new physics and great applicable potentials. The remarkable valley contrast and light emission promise such two-dimensional (2D) semiconductors a bright future of valleytronics and light-emitting diodes (LEDs). Though the electroluminescence (EL) has been observed in mechanically exfoliated small flakes of TMDs, considering real applications, a strategy that could offer mass-product and high compatibility is greatly demanded. Large-area and high-quality samples prepared by chemical vapor deposition (CVD) are perfect candidates toward such goal. Here, we report the first demonstration of electrically tunable chiral EL from CVD-grown monolayer WS2 by constructing a p–i–n heterojunction. The chirality contrast of the overall EL reaches as high as 81% and can be effectively modulated by forward current. The success of fabricating valley LEDs based on CVD WS2 opens up many opportunities for developing large-scale production of unconventional 2D optoelectronic devices.