LAUSR

Light-emitting nanocrystal quantum dots (QDs) are of high interest for use as down-conversion phosphors and direct emission sources in bulk solid-state devices and as reliable sources of single photons in quantum information science. However, these materials are prone to photo-oxidation that reduces emission quantum yield over time. Current commercial designs use device architectures that prevent oxidation without a quantitative understanding of degradation reactions. To, instead, prevent loss in functionality at the molecular level, the underlying properties of these reactions must be understood. Here, we use solid-state spectroscopy to study fundamental kinetic and thermodynamic parameters of photo-thermal degradation in single QDs, systematically varying ambient temperature and photon pump fluence. We describe the resulting degradation in emission with a modified form of the Arrhenius equation and show that this reaction proceeds via pseudo zero-order reaction kinetics by a surface assisted process with an activation energy of 40 kJ/mol. We note that the rate of degradation is ~12 orders of magnitude slower than the rate of excitonic processes, indicating that the reaction rate is not determined by electron or hole trapping. The reported analysis method will enable direct comparisons between differently engineered quantum emitters.