Ultra-Narrow Room-Temperature Emission from Single CsPbBr₃ Perovskite Quantum Dots

Semiconductor quantum dots (QDs) 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,¹ by using ab-initio molecular dynamics for simulating exciton-surface phonon interactions in structurally dynamic CsPbBr₃ QDs, 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).<br/>Ultra-narrow emission at room temperature is desired for conventional light-emitting devices and paramount for emerging quantum light sources.<br/><br/><b>Reference</b><br/>[1] Rainò, G. et al., Nat. Commun. 13, 2587 (2022).<br/>https://doi.org/10.1038/s41467-022-30016-0