Wei-Chang (David) Yang is a UMD Postdoctoral Researcher in Nanoscale Imaging Group. He received a B.S. and a M.S. in Materials Science and Engineering from the National Tsing Hua University, Taiwan and a Ph.D. in Materials Engineering from Purdue University. For his doctoral research, he fabricated and characterized nanoparticle ink-based kesterite thin-film solar cells. He developed a characterization protocol to study multinary semiconductor nanoparticles and thin-films for photovoltaic devices using analytical transmission electron microscopy (AEM). David is working with Renu Sharma designing an in situ vibrational and optical spectroscopy platform integrated with an environmental transmission electron microscope (ETEM) for the measurements of Raman and cathodoluminescence excitations.