MMAE Seminar - Dr. Zhengguo Xiao - Organic-Inorganic Hybrid Perovskite Materials for Optoelectronic Devices
Armour College of Engineering's Mechanical, Materials & Aerospace Engineering Department will welcome Dr. Zhengguo Xiao, a postdoctoral researcher in the Electrical Engineering Department at Princeton University, on Monday, January 30th, to present his lecture, Organic-Inorganic Hybrid Perovskite Materials for Optoelectronic Devices.
Abstract
Hybrid organic-inorganic perovskites are emerging as a new class of low-cost, solution processed semiconducting materials with favorable optoelectronic properties such as strong absorption coefficients, tunable bandgap, large and balanced electron and hole mobilities, long carrier diffusion lengths, small exciton binding energy, and unique defect properties. These characteristics have allowed for consistent and rapid progress in solar cell efficiency, which has risen dramatically from 3.8% to over 22% in fewer than five years. In comparison, the same improvement occurred over three decades for single crystal silicon solar cells. Owing to their facile solution processing, high color purity, and tunable bandgap, hybrid perovskites are also promising for light emitting diodes (LEDs). The external quantum efficiency of perovskite LEDs also increased dramatically from 0.1% to over 10% (my work) in the past two years.
In my talk, I will give a brief introduction to hybrid perovskite materials and its unique optoelectronic properties. Then I will describe several new techniques that I developed to increase the power conversion efficiency of perovskite solar cells. For example, two-step solution processing solves the issue of pinholes in perovskite films, and solvent annealing increases grain size and crystallinity. A novel phenomenon, ion migration induced switchable photovoltaic effect will also be discussed. I will also show my recent work on perovskite LEDs using novel self-assembled perovskite nanocrystallites with world record external quantum efficiency. Finally, I will discuss my future research on tuning the electrical, optical, magnetic, and structural properties of hybrid perovskites and their potential applications in electronic devices.
Biography
Zhengguo Xiao is a postdoctoral researcher in the Electrical Engineering department at Princeton University. He completed his PhD in Materials Engineering at University of Nebraska-Lincoln. His research has focused broadly on understanding the physics and design of solar cells, light emitting diodes, photodetectors, and memristors. By understanding the physical, chemical, and electrical properties of electronic materials, as well as the physics behind optoelectronic and electronic devices, he has fabricated several world record efficiency devices including polymer solar cells, hybrid perovskite solar cells, and LEDs.
Dr. Xiao is the lead author of publications in several eminent journals such as Nature Materials (cover), Nature Photonics (most read paper), Advanced Materials, and Energy and Environmental Science, and has coauthored more than 40 papers with more than 3,600 citations to date. He is the recipient of numerous awards and recognitions including the Materials Research Society's Student Award (2015) and Outstanding Research Assistant Award in UNL (2014).