Passivation and Interlayer Effect of Zr(i-PrO)4 on Green CuGaS2/ZnS/Zr(i-PrO)4@Al2O3 and Red CuInS2/ZnS/Zr(i-PrO)4@Al2O3 QD Hybrid Powders

Broadband emissive I–III–VI quantum dots (QDs) are synthesized as efficient and stable I–III–VI QDs to be used as eco-friendly luminescent materials in various applications. Here, we introduce the additional passivation of zirconium isopropoxide (Zr(i-PrO)₄) to improve the optical properties and environmental stability of green-emitting CuGaS₂/ZnS (G-CGS/ZnS) and red-emitting CuInS₂/ZnS (R-CIS/ZnS) QDs. The photoluminescence quantum yield (PLQY) of both resultant Zr(i-PrO)₄-coated G-CGS/ZnS and R-CIS/ZnS QDs reaches similar values of ~ 95%. In addition, the photostability and thermal-stability of G-CGS/ZnS/Zr(i-PrO)₄ and R-CIS/ZnS/Zr(i-PrO)₄ QDs are improved by reducing the ligand loss via encapsulation of the ligand-coated QD surface with Zr(i-PrO)₄. It is also proved that the Zr(i-PrO)₄-passivated interlayer mitigates the further degradation of I-III-V QDs from ligand loss even under harsh conditions during additional hydrolysis reaction of aluminum tri-sec-butoxide (Al(sec-BuO)₃), forming easy-to-handle G-CGS/ZnS and R-CIS/ZnS QD-embedded Al₂O₃ powders. Therefore, the introduction of a Zr(i-PrO)₄ complex layer potentially provides a strong interlayer to mitigate degradation of I–III–VI QD-embedded Al₂O₃ hybrid powders as well as passivation layer for protecting I–III–VI QD.