题  目：Interfacial Charge Transfer and Recombination Dynamics in van der Waals Heterojunctions of 2D Semiconductors 时  间：6月21日  下午4:00—5:30 地  点：玉泉校区微电子楼3楼会议室 报告人：朱海明教授

专家介绍

Haiming Zhu got his B.S degree from Chemistry in University of Science and Technology of China in 2008 and PhD in Physical Chemistry from Tim Lian’s group in Emory University in 2014. Afterwards, he worked as a postdoc scientist in Xiaoyang Zhu’s group in Columbia University in the City of New York. He joined Zhejiang University Chemistry Department as a tenure-track professor from July, 2016. He is interested at spectroscopically study of excited state and carrier dynamics in low dimensional nanostructured materials and their application in optoelectronic conversion and light emission applications. Currently his group in ZJU are working on physical chemistry in two dimensional materials, heterostructures and devices. He has published more than 40 papers including Science, Nature Materials, Advanced Materials, Nature Communication, Journal of American Chemical Society, Nano Letter, et al. He has been awarded several awards including DPC Sturge Prize, Thousand Talent Program for Young Outstanding Scientists.

报告内容

Heterojunctions of transition metal dichalcogenides (TMDC) are being explored for optoelectronics, photovoltaics and spin-valleytronics at the two-dimensional (2D) limit. Using ultrafast microscopic transient spectroscopy, we investigated the interfacial charge transfer and recombination dynamics in 2D MoS2/WSe2 heterojunctions as a function of interlayer momentum mismatch. The observed ultrafast (< 40 fs) interfacial charge transfer is independent of the relative orientation between the two layers, indicating a hot-carrier mediated charge transfer mechanism. The lifetime of charge transfer excitons span two orders of magnitude (0.04 - 3 ns) with no clear dependence on relative orientation thus momentum mismatch, in accordance with the defect-mediated non-radiative recombination mechanism. Our results suggest the importance of defect reduction in revealing the intrinsic properties of charge transfer excitons in two dimensional van der Waals heterojunctions.