Photoactivation, photobleaching and photoetching of CdS quantum dots − Role of oxygen and solvent

- Photodegradation and photoetching of CdS quantum dots is not caused by oxygen presence.
- Oxygen slows down both photodegradation and photoetching.
- Time-controlled photoethcing provides the very precise control of QDs spectral properties.

Photostability of CdS quantum dots (QDs) under monochromatic UV irradiation in the most common non-polar solvents (chloroform, toluene, hexane) was investigated in air-saturated and thoroughly degassed solutions. For air-saturated solutions photoactivation and fluorescence quantum yield increase was observed at the initial stage of photolysis. Solvent-dependent photobleaching was observed at the medium photolysis times. Then luminescence quantum yield reached the plateau and photoetching started upon prolonged irradiation resulting in QDs size decrease. Initial photoactivation was observed in air-saturated solutions only, whilst photobleaching and photoetching took place independently on the oxygen presence rising a question on the mechanism of these processes and a role of oxygen. Photoetching was applied for the extremely precise control of nanoparticles spectral properties.

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