Speaker: Qi Dong, MSE

Title: Organo-Metal Halide Perovskite Lasers

Abstract
Organo-metal halide perovskites as an emerging type of semiconductor materials have attracted
increasing attention in recent years due to their superior properties such as direct-bandgap, large
absorption coefficient, defect tolerance, long carrier diffusion length, long carrier lifetime and
high photoluminescence quantum yield (PLQY). More importantly, their broadband tunability
and solution-processability provide a material platform that enables a low-cost fabrication of
lasers with different emission wavelengths covering the entire visible spectrum. Among
perovskite lasers with different cavities, distributed feedback (DFB) lasers are of great interest
due to their single-mode operation, low threshold, and the utilization of Bragg diffraction instead
of high-quality facets or mirrors to provide optical feedback, making them an ideal candidate for
coherent light sources in various photonic applications.
In this seminar, I will first give a review on perovskite materials from the perspective of
compositions, structures, and properties, followed by a focus on perovskite DFB lasers including
original studies where a facile and systematic methodology of cavity fabrication and fine-tuning
for perovskite DFB lasers is demonstrated. To fabricate the DFB cavity, a novel nanoimprint
method assisted by polymer additive will be introduced. To fine-tune the cavity, a systematic
optical analysis will be presented, which includes an understanding of the laser optics in DFB
structures and a powerful characterization technique (angle-resolved-PL-spectra (ARPS)) that
probes the optical mode distribution. Based on the methodology, perovskite DFB lasers with an
optimized performance are achieved.

Biography
Qi Dong is a doctoral candidate under the supervision of Prof. Franky So in the Department of
Material Science and Engineering at North Carolina State University (NCSU). Before joining in
NCSU, he received Bachelor of Science in Applied Physics from Hong Kong Baptist University
(HKBU) and Master of Philosophy in Physics from the University of Hong Kong (HKU). Qi’s
research focuses on the applications of halide perovskites in various optoelectronic devices
including photovoltaics, light-emitting-diodes and lasers.