Speaker:  Dr. Chun-Yuan Cheng (鄭畯元 博士), National Tsing Hua University

Time: 1:20PM, 11/15, 2021

Title: Very Robust Spray-Synthesized CsPbI3 Quantum Emitters with Ultrahigh Room-
Temperature Cavity-Free Brightness and Self-Healing Ability

Abstract: 

Although colloidal lead halide perovskite quantum dots (PQDs) exhibit desirable emitter 
characteristics with high quantum yields and narrow bandwidths, instability has limited 
their applications in devices. In this paper, we describe spray-synthesized CsPbI3 PQD 
quantum emitters displaying strong photon antibunching and high brightness at room 
temperature and stable performance under continuous excitation with a high-intensity 
laser for more than 24 h. Our PQDs provided high single-photon emission rates, exceeding 
9 × 106 count/s, after excluding multiexciton emissions and strong photon antibunching, 
as confirmed by low values of the second-order correlation function g(2)(0) (reaching 
0.021 and 0.061 for the best and average PQD performance, respectively). With such high 
brightness and stability, we applied our PQDs as quantum random number generators, which 
demonstrably passed all of the National Institute of Standards and Technology’s 
randomness tests. Intriguingly, all of the PQDs exhibited self-healing behavior and 
restored their PL intensities to greater than half of their initial values after 
excitation at extremely high intensity. Half of the PQDs even recovered almost all of 
their initial PL intensity. The robust properties of these spray-synthesized PQDs 
resulted from high crystallinity and good ligand encapsulation. Our results suggest that 
spray-synthesized PQDs have great potential for use in future quantum technologies 
(e.g., quantum communication, quantum cryptography, and quantum computing).