关于举行德国马普高分子所王海教授学术报告的通知

2023-03-24 1288

报告题目：Unveiling Charge Transport Effects in Low-dimensional Optoelectronic Materials

报告人：王海教授（德国马普高分子所）

邀请人：陈东成副教授

报告时间：2023年3月28日（周二）上午10:00-11:30

报告地点：北区科技园1号楼发光国重502会议室

内容摘要:

The conversion of light into electrical currents is a fundamental process underlying the operation of varied optoelectronic devices including photovoltaics and photodetectors. Understanding the underlying photophysics, e.g. generation and transport of charge carriers in the photoactive materials following photoexcitations, is crucial for improving the energy conversion efficiency of devices.

Layered two-dimensional (2D) materials are emerging building blocks for the next generation electronics and optoelectronics. Since the discovery of graphene, the family of the 2D materials have been largely expanded, including e.g. transition metal dichalcogenide and MXenes. The recent emergence of conductive semiconducting organic layers (e.g. metal covalent organic framework) has further extended the 2D material library and provided new functionalities for applications.

In this talk, I will first provide some basics on ultrafast THz spectroscopy and demonstrate its strength in characterization of electrical transport properties1-3 of charge carriers, low energy excitations4 in solids and charge transfer5-6 dynamics across interfaces in a contact-free manner for low-dimensional materials. I will then discuss some recent work from us related to understanding charge transport mechanism in novel low-dimensional materials including (1) unveiling band-like charge transport in organic frameworks7 and (2) the role of polaron formation in tuning charge transport effect in MXenes8.

References

1. Wenhao Zheng et.al, Probing Carrier Dynamics in sp3-Functionalized Single-Walled Carbon Nanotubes with Time-Resolved Terahertz Spectroscopy, ACS Nano 2022, 16, 6, 9401–9409

2. Wenhao Zheng et.al, Photoconductivity Multiplication in Semiconducting Few-Layers MoTe2, Nano Letters 2020, 20, 8, 5807–5813.

3. Heng Zhang et.al, Highly Mobile Hot Holes in Cs2AgBiBr6 Double Perovskite, Science Advances 2021, eabj9066.

4. Alexander Tries et.al, Experimental Observation of Strong Exciton Effects in Graphene Nanoribbons, Nano Letters 2020, 20, 5, 2993–3002.

5. Shuai Fu et.al, Long-Lived Charge Separation Following Pump-Energy Dependent Ultrafast Charge Transfer in Graphene/WS2 Heterostructures, Science Advances 2021, 7, eabd9061.

6. Shuai Fu et.al, Reversible Electrical Control of Interfacial Charge Flow across van der Waals Interfaces, Nano Letters, 2023, 23, 1850–1857

7. Shuai Fu et.al, Outstanding Charge Mobility by Band Transport in Two-Dimensional Semiconducting Covalent Organic Frameworks, Journal of the American Chemical Society, 2022, 144, 16, 7489–7496.

8. Wenhao Zheng et.al, Band Transport by Large Fröhlich Polarons in MXenes, Nature Physics 2022, 18, 544-550.

个人简介：

Dr. Hai Wang studied materials science at Zhejiang University and obtained his degree in 2009. Between 2009 and 2011, he finished a joint master program in nanoscience at University of Leuven (2009-2010) in Belgium and Delft University of Technology in the Netherlands (2010-2011), supported by the Erasmus Mundus fellowship. From 2012, Hai Wang started his PhD at Max Planck institute for polymer research (MPI-P) in Mainz with the support of a fellowship from MAINZ (graduate school of excellence, materials science in Mainz). In his PhD, Hai worked with Prof. dr. Mischa Bonn to investigate ultrafast charge transfer processes at quantum dot and oxide interfaces, and graduated with Summa Cum Laude (with highest honors) in 2016. After spending 1 year in the group of Mathias Kläui at University of Mainz as a postdoc, Hai started his independent research group “Nano- optoelectronic materials” in the Molecular Spectroscopy department at MPI-P in 2017. Employing time-resolved, ultrafast spectroscopies (THz spectroscopy, transient absorption etc.), the central theme of Hai’s current research lies in understanding fundamental charge carrier dynamics and low-energy excitations in solid-state low-dimensional materials and interfaces, relevant for energy and optoelectronic applications.