Highly Stable and Spectrally Tunable Gamma Phase Rb x Cs 1– x PbI 3 Gradient‐Alloyed Quantum Dots in PMMA Matrix through A Sites Engineering

Abstract Perovskite quantum dots are emerging as new generation functional materials for display applications. The issue of perovskite “red wall” has been an obstacle for their use in display technology. In this study, the fabrication of γ‐Rb x Cs 1– x PbI 3 gradient‐alloyed quantum dots in polymeric matrix through a rational designed in situ fabrication process is reported. The formation of γ‐Rb x Cs 1– x PbI 3 gradient‐alloyed structure can be explained by considering the lattice mismatch and solubility difference between γ‐CsPbI 3 and RbPbI 3 . The photoluminescence emission of γ‐Rb x Cs 1– x PbI 3 gradient‐alloyed quantum dots can be tuned from 675 to 620 nm with full width at half maximum of 31 nm and maximum quantum yields up to 91%. Importantly, the packaged films retained about 95% of its original photoluminescence intensity after 1000 h aging at the test conditions of 60 °C, 90% RH and 40 °C, 90% RH with 3 mW cm −2 , 455 nm blue light irradiation, respectively. By integrating a red and green dual emissive film with blue Mini LEDs, a LCD backlight of a color space of ≈130% of NTSC 1931 standard is achieved with matching rate of 100%.