Nanoscale Encapsulation of Perovskite Nanocrystal Luminescent Films via Plasma-Enhanced SiO₂ Atomic Layer Deposition

Photoluminescence perovskite nanocrystals (NCs) have shown significant potential in optoelectronic applications in view of their narrow band emission with high photoluminescence quantum yields and color tunability. The main obstacle for practical applications is to obtain high durability against an external environment. In this work, a low temperature (50 °C) plasma-enhanced atomic layer deposition (PE-ALD) protection strategy was developed to stabilize CsPbBr₃ NCs. Silica was employed as the encapsulation layer because of its excellent light transmission performance and water corrosion resistance. The growth mechanism of inorganic SiO₂ via PE-ALD was investigated in detail. The Si precursor bis(diethylamino)silane (BDEAS) reacted with the hydroxyl groups (-OH) and thereby initiated the subsequent silica growth while having minimal influence to the organic ligands and did not cause PL quenching. Subsequently, O₂ plasma with high reactivity was used to oxidize the amine ligands of the BDEAS precursor while did not etch the NCs. The obtained CsPbBr₃ NCs/SiO₂ film exhibited exceptional stability in water, light, and heat as compared to the pristine NC film. Based on this method, a white light-emitting diode with improved operational stability was successfully fabricated, which exhibited a wide color gamut (∼126% of the National Television Standard Committee). Our work successfully demonstrates an efficient protection scheme via the PE-ALD method, which extends the applied range of other materials for stabilization of perovskite NCs through this approach.