Pure red-emitting composites with nearly 100% solid-state photoluminescence quantum yield obtained via the in situ growth of Sr2+-doped hybrid halide CsPb(Br,I)3 perovskite quantum dots in mesoporous silica

Abstract

A red-emitting composite with the emission band peaking at around 635 nm, a near-unity photoluminescence quantum yield (PLQY) and a full width at half maximum (fwhm) of 35 nm was achieved through the in situ growth of Sr²⁺-doped CsPb(Br_0.4I_0.6)₃ perovskite quantum dots (PeQDs) within mesoporous silica. Partial substitution of Pb²⁺ with Sr²⁺ increased the PLQY of CsPb(Br_0.4I_0.6)₃ PeQDs from 26.4% to 78.1%, which was attributed to an increase in the radiative recombination rate of excitons in the PeQDs via Sr²⁺ doping. Mesoporous silica encapsulation further enhanced the PLQY of Sr²⁺-doped CsPb(Br_0.4I_0.6)₃ PeQDs to nearly 100%. This enhancement can be primarily attributed to the passivation of surface defects in PeQDs through mesoporous silica encapsulation, which reduces the nonradiative recombination of excitons and significantly extends luminescence lifetime. A white light-emitting diode (LED) with a color gamut as wide as 88% of the National Television Standards Committee (NTSC) standard and a color rendering index as high as 92 was constructed using the obtained PeQDs-based composite as a red color converter.