Seminar Speaker: Franky So, NC State MSE

Organic and Perovskite Photonics: From Spontaneous Light Emission, Lasing to Superfluorescence

Abstract

Both organic semiconductors and hybrid perovskites are interesting classes of emitters for display applications because of their low-cost solution processability and wide wavelength tunability. In this talk, we will discuss how we can manipulate the light output using nanophotonic structures for applications beyond displays. The presentation will be divided into three parts. First, we will discuss how we use nanostructures to enhance the light output and control the directionality and polarization of the emitted light from an OLED. Specifically, we will present how we use Angle-Resolve Electroluminescence spectroscopy (ARES), an optical characterization technique developed in our laboratory, to characterize the light output of a light-emitting device and the photonic band structure of a photonic crystal. Second, making use of the nanostructures we developed, we can design a laser cavity to fabricate perovskite lasers with a low threshold. Here, we will also discuss how the film morphology affects the exciton dynamics and population required for lasing, and how we tune the laser cavity to optimize the laser performance. Finally, we will present our recent discovery of high-temperature superfluorescence in halide perovskites. Superfluorescence is a low-temperature quantum phenomenon in which an ensemble of photoexcited dipoles is spontaneously synchronized leading to the formation of a macroscopic quantum coherence phase. This research was done in collaboration with Professor Kenan Gundogdu in Physics. I will present the Gundogdu QAVI (quantum analog vibrational isolation) Model to explain how the quantum phase is protected in hybrid perovskites and explain why high-temperature superfluorescence can be observed in this unique material system.

Speaker Biography

Franky So received his Ph.D. degree in electrical engineering from the University of Southern California in 1991. He was previously the group manager at Motorola Corporate Research Laboratories working on the development of OLEDs. In 2001, he joined OSRAM Opto Semiconductors and became the Head of OLED Research. He joined the University of Florida in 2005 and became the Rolf E. Hummel Professor in Electronic Materials in the Department of Materials Science and Engineering. In 2015, he joined the Department of Materials Science and Engineering at North Carolina State University where he is currently the Walter and Ida Freeman Distinguished Professor. While at Motorola, he was named the Distinguished Innovator and Master Innovator. Dr. So holds 120 issued patents. He is the Editor-in-Chief of the journal Materials Science and Engineering Reports and serves as an Associate Editor for the IEEE Journal of Photovoltaics, IEEE Journal of Display Technology, ACS Applied Electronic Materials, and Organic Electronics. So is a Distinguished Lecturer of the IEEE Photonics Society, a Fellow of the National Academy of Inventors, and a Fellow of MRS, IEEE, SID, OSA, and SPIE.