Seminar: Charge Traps Enabled High Gain Photodetectors

Abstract:

Very weak UV light detection is critically important for defense, air space, and radiation sensing applications. Single photon level detection needs UV photodetectors with high gain and low noise. Here, we report a low-cost UV hybrid photodetector that has a huge internal gain of 4,100 under low bias less than 10 volts, enabled by the interfacial trapped charge controlled charge injection. The active materials are organic semiconductors, such as fullerenes, which have strong absorption in UV range. The insertion of buffer layer that composes crosslinked polymer with zinc-oxide nanocrystals simultaneously harvests the high gain of a photoconductor as well as the low noise current of an organic photodiode. Strikingly, the noise of the fullerene photodetector with buffer layer was reduced to 7~10 fA Hz^-0.5. The combination of low noise and high gain in these photodetectors resulted in a very large specific detectivity of 4×10¹⁵ Jones, which is 2-3 times larger than that of commercial available best silicon and GaN photodetectors in the same spectrum range. These photodetectors have a super large linear dynamic range in excess of 120 dB under light intensity between 10 fW/cm²~100 mW/cm², better than any reported solid state photodetectors. Recently progress on reducing the driving voltage to below 1 V using organometal trihalide perovskite materials will be also presented.

About the Speaker:

Jinsong Huang received his Ph.D. degree in Material Science and Engineering from the University of California-Los Angeles in 2007. After working in Agiltron Inc. as a research scientist for two years, he joined the University of Nebraska-Lincoln (UNL) in 2009 as an assistant professor in the Department of Mechanical Engineering and Nebraska Center for Materials and Nanoscience. He was promoted to associate professor in 2014.  His current research interests include solution processed electronic materials for applications in sensing, energy and consumer electronics.  He is the coauthors/editors of over 70 publications, and over 10 patents, 2 book chapters and 1 book. He serves as the Chair of Material Engineering Ph.D. Program, and was selected as William E. Brooks Engineering Leadership Fellow in 2014. He serves as an associate editor for Scientific Reports. He has received many prestigious awards, such as NSF CAREER Award (2013), Edgerton Innovation Award (2012), College Faculty Research and Creative Activity Award (2011) and DTRA Young Investigator Award (2010).

Hosted by Professor Lei Cao