Enhanced blue emission in silica-confined mixed-halide perovskite quantum dots via releasing residual stress

Abstract

Perovskite quantum dots (QDs) confined within solid matrices via calcination methods exhibit superior environmental stability compared to colloidal perovskite QDs. However, matrix-confined perovskite QDs generally display lower photoluminescence quantum yield (PLQY) than their colloidal counterparts, especially in the case of blue-emitting mixed-halide CsPb(Cl/Br)₃ QDs. Here, we identify residual tensile stress, originating from the mismatch in thermal expansion coefficients between the perovskite and the matrix, as a key factor responsible for the suppressed luminous efficiency in silica-confined CsPb(Cl/Br)₃ QDs. Furthermore, we demonstrate that a simple hydrothermal treatment enables stress release in these silica-confined QDs, leading to a significant enhancement in their PLQY. The resulting stress-free silica-confined CsPb(Cl/Br)₃ QDs exhibit record-high PLQYs among reported blue-emitting perovskite QDs synthesized via calcination methods, even approaching the PLQY of colloidal QDs. In addition, we find that stress release effectively suppresses both photoinduced halide segregation and thermal-induced emission quenching in these silica-confined CsPb(Cl/Br)₃ QDs. This work provides a new perspective for achieving blue-emitting perovskite QDs with high PLQY and stability.

Keywords

blue emission / mixed-halide perovskites / quantum dots / residual stress / stability

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