Rainò Gabriele, Yazdani Nuri, Boehme Simon C, Kober-Czerny Manuel, Zhu Chenglian, Krieg Franziska, Rossell Marta D, Erni Rolf, Wood Vanessa, Infante Ivan, Kovalenko Maksym V
Department of Chemistry and Applied Biosciences, Institute of Inorganic Chemistry, ETH Zurich, 8093, Zurich, Switzerland.
Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland.
Nat Commun. 2022 May 11;13(1):2587. doi: 10.1038/s41467-022-30016-0.
Semiconductor quantum dots have long been considered artificial atoms, but despite the overarching analogies in the strong energy-level quantization and the single-photon emission capability, their emission spectrum is far broader than typical atomic emission lines. Here, by using ab-initio molecular dynamics for simulating exciton-surface-phonon interactions in structurally dynamic CsPbBr quantum dots, followed by single quantum dot optical spectroscopy, we demonstrate that emission line-broadening in these quantum dots is primarily governed by the coupling of excitons to low-energy surface phonons. Mild adjustments of the surface chemical composition allow for attaining much smaller emission linewidths of 35-65 meV (vs. initial values of 70-120 meV), which are on par with the best values known for structurally rigid, colloidal II-VI quantum dots (20-60 meV). Ultra-narrow emission at room-temperature is desired for conventional light-emitting devices and paramount for emerging quantum light sources.
长期以来，半导体量子点一直被视为人工原子，尽管在强能级量子化和单光子发射能力方面存在总体类比，但它们的发射光谱远比典型的原子发射线宽得多。在这里，我们通过使用从头算分子动力学来模拟结构动态的CsPbBr量子点中的激子-表面-声子相互作用，随后进行单量子点光谱学研究，证明这些量子点中的发射线展宽主要由激子与低能表面声子的耦合所控制。对表面化学成分进行适度调整，可以实现小得多的发射线宽，即35-65 meV（初始值为70-120 meV），这与结构刚性的胶体II-VI量子点的最佳已知值（20-60 meV）相当。室温下的超窄发射对于传统发光器件来说是理想的，对于新兴的量子光源来说则至关重要。
