Cracking the Mystery of Light Emitting CsPbBr₃
Hanwei Gao
Department of Physics, Florida State University, Tallahassee, FL 32306
hgao3@fsu.edu

The halide perovskite CsPbBr3 has shown its promises for green light emitting diodes. The optimal conditions of photoluminescence and the underlying photophysics, however, remain controversial. To address the inconsistency seen in the previous reports and to offer high-quality luminescent materials that can be readily integrated into functional devices with layered architecture, we created thin films of CsPbBr₃/Cs₄PbBr₆ composites based on a dual-source vapor-deposition method. With the capability of tuning the material composition in a broad range, CsPbBr₃ is identified as the only light emitter in the composites. Interestingly, the presence of the photoluminescence-inactive Cs4PbBr6 can significantly enhance the light emitting efficiency of the composites. The unique negative thermal quenching observed near the liquid nitrogen temperature indicates that a type of shallow states generated at the CsPbBr₃/Cs₄PbBr₆ interfaces is responsible for the enhancement of photoluminescence.

Biography
Dr. Hanwei Gao received B.S. in Physics from University of Science and Technology of China in 2004 and Ph.D. in Materials Science from Northwestern University, USA in 2009. Since 2010, he worked at University of California-Berkeley as a Postdoctoral Researcher where he studied plasmonic enhanced solar energy devices, both solid state photovoltaics and photoelectrochemical water splitting. Dr. Gao joined the Florida State University as an Assistant Professor in Physics in the Fall 2013. His research since then has been focusing on photoresponse and charge transport behaviors of photoactive materials with potential for optoelectronic applications.