IAMS/NTU Chem Lecture on Nov. 13, 3:30pm, Poe Lecture Hall, Prof. Wei-Ting Hsu 徐瑋廷助理教授
消息來源：原分所
截止日期：2025-11-13
IAMS/NTU Chemistry Joint Lecture中研院原分所與臺大化學系聯合演講
Title: Probing Tunable Exciton States and Dynamics in WS2/WSe2 Moiré Heterobilayers
Speaker: Prof. Wei-Ting Hsu (Department of Physics, National Tsing Hua University) 徐瑋廷助理教授 (國立清華大學物理學系)
Time: 3:30 PM, November 13 (Thursday), 2025
Place: Dr. Poe Lecture Hall, IAMS (本所浦大邦講堂臺大校園內)
Contact: Dr. Yang-hao Chan 詹楊皓博士
Abstract: Transition metal dichalcogenide (TMD) moiré heterobilayers provide a versatile platform for exploring correlated excitonic phenomena and developing novel optoelectronic devices. The key to this cutting-edge research lies in high-quality 2D moiré heterostructures. In this talk, I will present the fabrication of TMD moiré heterobilayers and show successful examples, including gate-tunable devices, freestanding moiré structures, and samples integrated into high-pressure diamond anvil cells. Building on this platform, two related studies will be discussed. The first study focuses on tuning the exciton states of WS2/WSe2 moiré heterobilayers under hydrostatic pressure. We observed a conversion of interlayer excitons driven by inter-valley carrier transfer, which in turn determines the inter-valley band offsets. The second study explores exciton dynamics in WS2/WSe2 moiré heterobilayers. The type-II band alignment, combined with the moiré superlattice, leads to nontrivial exciton annihilation and upconversion processes. We find an ultralow exciton-exciton annihilation coefficient (10-5cm2s-1), nearly two orders of magnitude smaller than that in monolayer TMDs, and observe layer selective upconversion that leads to the emergence of long-lived excitons in WSe2. Together, our findings demonstrate the tunability of moiré excitons and reveal their unique dynamics in WS2/WSe2 heterobilayers.