Durable and photostable zinc sulfide particles

Zinc sulfide has unique and easily modifiable photophysical properties and is a promising candidate for photocatalysis and optoelectronic devices. However, ZnS suffers from corrosive decomposition during excitation processes like UV irradiation, which drastically limits its field of potential applications.

Scientists now report on a complete photostabilisation of individual ZnS particles by a dense, durable, and only 3‐nm‐thick Al₂O₃ layer, produced by rotary atomic layer deposition (ALD) is reported. In contrast to bare ZnS, the coated particles do not suffer from photocorrosive degradation even under long‐term or high power UV irradiation. The presence of a protection layer covering the entire ZnS surface was additionally confirmed by microscopic and spectroscopic investigations of particle cross‐sections.

Suppressing hydrolysis

Durability tests of the as‐prepared Al₂O₃ layer upon prolonged exposure to water reveal a significant decrease in the protection capability of the layer, which is ascribed to the hydrolysis of the amorphous Al₂O₃. A calcination step at 1000°C after the ALD treatment, which leads to crystallisation of the amorphous Al₂O₃ layer, successfully suppresses this hydrolysis and produces an insulating, dense, and inert protection layer.

The study has been published in Advances Functional Materials, Volume 31, Issue 14, 2021.