Prof. Zexiang Shen[Nanyang Technological University (NTU), Singapore]

Title:  CONFIGURING THE STRUCTURES OF 2D MATERIALS AND PEROVSKITES AND THEIR APPLICATIONS

Time:  10:00 -10:45 am, Wednesday, November. 14, 2018

Place: Conference room 410, HPSTAR (Shanghai)

Host: Xujie Lü

Polycom: 02120004

Abstract:

The optical and electronic structures of two-dimensional (2D) materials and perovskites often show very strong layer-dependent properties. The properties can also be tuned by stacking configuration, which allows us to build electro and optical devices with the same material and the same thickness. Detailed understanding of the inter-layer interaction will help greatly in tailoring the properties of 2D materials for applications, e.g. in pn junction, transistors, solar cells and LEDs. Raman/Photoluminescence (PL) spectroscopy and imaging have been extensively used in the study of nano-materials and nano-devices. They provide critical information for the characterization of the materials such as electronic structure, optical property, phonon structure, defects, doping and stacking sequence.

In this talk, we use Raman and PL techniques and electric measurements, as well as simulation to study 2- and 3-layer 2D samples and Perovskite materials. The Raman and PL spectra also show clear correlation with layer-thickness and stacking sequence. Electrical experiments and ab initio calculations reveal that difference in the electronic structures mainly arises from competition between spin-orbit coupling and interlayer coupling in different structural configurations.

Biography of the Speaker:

Professor, School of Physical and Mathematical Sciences

Professor, School of Materials Science and Engineering

Co-Director, Centre for Disruptive Photonics Technologies.

Nanyang Technological University (NTU) Singapore

His main research areas include carbon related materials, especially graphene.  His work involves spectroscopic and theoretical study of few-lay graphene and folded graphene, graphene intercalation study, graphene based composites for energy harvesting (Li Ion batteries and supercapacitors) and nano electronics; He also works on developing near-field Raman spectroscopy/imaging techniques and the study of plasmonics structures where some very fundamental questions remain to be answered. He has been active in the study of 2D materials and Perovskites using ultra Low wavenumber Raman spectroscopy, PL techniques and time resolved spectroscopy in combination with high pressure and low temperature.

He was awarded the NTU Nanyang Award for Research and Innovation 2009 as well as the Gold Medal for Research Excellence by Institute of Physics Singapore in 2011.