PbI2–MoS2 Heterojunction: van der Waals Epitaxial Growth and Energy Band Alignment

• Published in: The journal of physical chemistry letters Vol. 10; no. 15; pp. 4203 - 4208
• Main Authors: Xiao, Junting, Liu, Jinxin, Sun, Kuanglv, Zhao, Yuan, Shao, Ziyi, Liu, Xiaoliang, Yuan, Yongbo, Li, Youzhen, Xie, Haipeng, Song, Fei, Gao, Yongli, Huang, Han
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01.08.2019
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.9b01665

van der Waals (vdW) epitaxy offers a promising strategy without lattice and processing constraints to prepare atomically clean and electronically sharp interfaces for fundamental studies and electronic device demonstrations. Herein, PbI2 was thermally deposited at high-vacuum conditions onto CVD-grown monolayer MoS2 flakes in a vdW epitaxial manner to form 3D–2D heterojunctions, which are promising for vdW epitaxial growth of perovskite films. X-ray diffraction, X-ray photoemission spectroscopy, Raman, and atomic force microscopy measurements reveal the structural properties of the high-quality heterojunctions. Photoluminescence (PL) measurements reveal that the PL emissions from the bottom MoS2 flakes are greatly quenched compared to their as-grown counterparts, which can be ascribed to the band alignment-induced distinct interfacial charge-transfer behaviors. Strong interlayer excitons can be detected at the PbI2/MoS2 interface, indicating an effective type II band alignment, which can be further confirmed by ultraviolet photoemission spectroscopy measurements. The results provide a new material platform for the application of the vdW heterojunctions in electronic and optoelectronic devices.