Date(s) - 23 Oct 2018
10:00 AM - 11:00 AM
3043 ECpE Building Addition
Sponsored by The Optical Society.
Speaker: Liang-Yao Chen, Professor of Optical Science and Engineering at Fudan University
Title: High Efficiency of Photon-to-Heat Conversion Based on the Thermal-Electric Bi2Te3 Film Structure in the Broad Wavelength Region of 250-1200 nm
Abstract: In order to overcome the physical limits, the ways to realize high efficiencies of photon-to-heat conversion close to the theoretical limit in the broad wavelength region of solar radiation had been studied. In terms of numerical calculations based on the spectral properties of multilayer stacks with different metal materials and film thickness, several typical multilayered film structure (4-8 layers as applied) using the transition metals as the thin solar absorbing layers were fabricated on the Si or K9 glass substrate by using the magnetron sputtering method. In more recent studies, 4-layered SiO2/Bi2Te3/SiO2/Cu film structures were designed and fabricated with the optical properties being investigated in the wavelength region of 250-1200 nm for their promising applications for direct solar-thermal-electric conversion. The typical film sample with the structure of SiO2 (66.6 nm)/Bi2Te3 (7.0 nm)/SiO2 (67.0 nm)/Cu (>100 nm) was deposited by magnetron sputtering. The experimental results agree well with the simulated ones to have an average optical absorption of 96.5% except in the shorter wavelength region of 250-500 nm, which demonstrate the superior absorption property film due to the randomly rough surface of the Cu layer resulting possibly from the higher deposition power condition. The high reflectance of the film structure showing in the long wavelength region of 2-20μm will result in a low thermal emittance of 0.064 at 600K. The simpler 4-layered structure with the thermal-electric material of Bi2Te3 used as the absorption layer may provide a straightforward way to fulfill the solar-thermal-electric conversion more efficiently in the future.
Bio: Liang-Yao Chen received his Ph.D. in Physics from Iowa State University in 1987. He received his M.S. in Physics from Fudan University in 1981. He studies the optical and magneto-optical properties of solids, including metals, metal alloys, semiconductors, thin films, magnetic and magneto-optical materials based on new optical methods and instrument, such as the ellipsometry, reflectance, Kerr and Faraday spectroscopy, and so on, in a variety of conditions. More than 300 referred research papers were published, over 150 presentations were given, and more than 15 patents were approved. He is now a professor with the Department of Optical Science and Engineering at Fudan University in Shanghai, China.
ECpE Seminar Host: Meng Lu