Park, Young-Shin Bae, Wan Ki Baker, Thomas Lim, Jaehoon Klimov, Victor I. 2024-01-20T05:34:47Z 2024-01-20T05:34:47Z 2021-09-05 2015-11 1530-6984 https://pubs.kist.re.kr/handle/201004/124824 Nanocrystal quantum dots (QDs) are attractive materials for applications as laser media because of their bright, size-tunable emission and the flexibility afforded by colloidal synthesis. Nonradiative Auger recombination, however, hampers optical amplification in QDs by rapidly depleting the population of gain-active multiexciton states. In order to elucidate the role of Auger recombination in QD lasing and isolate its influence from other factors that might affect optical gain, we study two types of CdSe/CdS core/shell QDs with the same core radii and the same total sizes but different properties of the core/shell interface ("sharp" vs "smooth"). These samples exhibit distinctly different biexciton Auger lifetimes but are otherwise virtually identical. The suppression of Auger recombination in the sample with a smooth (alloyed) interface results in a notable improvement in the optical gain performance manifested in the reduction of the threshold for amplified spontaneous emission and the ability to produce dual-color lasing involving both the band-edge (1S) and the higher-energy (1P) electronic states. We develop a model, which explicitly accounts for the multiexciton nature of optical gain in QDs, and use it to analyze the competition between stimulated emission from multiexcitons and their decay via Auger recombination. These studies re-emphasize the importance of Auger recombination control for the realization of real-life QD-based lasing technologies and offer practical strategies for suppression of Auger recombination via "interface engineering" in core/shell structures. English AMER CHEMICAL SOC AMPLIFIED SPONTANEOUS EMISSION STIMULATED-EMISSION LOW-THRESHOLD OPTICAL GAIN SEMICONDUCTOR SUPPRESSION NANOCRYSTALS Effect of Auger Recombination on Lasing in Heterostructured Quantum Dots with Engineered Core/Shell Interfaces Article 10.1021/acs.nanolett.5b02595 1 NANO LETTERS, v.15, no.11, pp.7319 - 7328 NANO LETTERS 15 11 7319 7328 scie scopus 000364725400023 2-s2.0-84946924464 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article AMPLIFIED SPONTANEOUS EMISSION STIMULATED-EMISSION LOW-THRESHOLD OPTICAL GAIN SEMICONDUCTOR SUPPRESSION NANOCRYSTALS quantum dot semiconductor nanocrystal core/shell heterostructure Auger recombination optical gain lasing