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Owing to their composition-tunable and narrow emissions and high photoluminescence quantum yield (PLQY), inorganic halide perovskite quantum dots (IPQDs) are a promising option for wide color gamut displays. However, their practical applications have been limited by their lattice structure instability and surface defect states. Herein, CsPbBr3:KBF4@SiO2 with improved stability and optical properties is successfully synthesized with a two-step optimization of fluorine (F) anion doping and SiO2 in situ coating. Compared with bromide (Br), higher electronegativity and a smaller radius of F lead to stronger binding energy with Pb2+. Also, F anions can occupy surface Br vacancies. Then, benefiting from the acidic environment provided by BF4− hydrolysis, tetraethyl orthosilicate (TEOS) can be more easily hydrolyzed on the CsPbBr3:KBF4 surface to generate SiO2 coating, thus further passivating lattice defects and improving environmental stability. Importantly, the PLQY of CsPbBr3:KBF4@SiO2 achieves 85%, and the stability has been greatly improved compared with pure CsPbBr3. Finally, CsPbBr3:KBF4@SiO2/PDMS, CsPbI3/PDMS, and CsPbCl3/PDMS composites with narrow emissions are applied to replace traditional phosphors as color converters for direct-view light-emitting diode (LED) displays or liquid crystal display (LCD) backlights. The color gamut reaches 118.22% under the NTSC standard. Concerning the display field, it suggests likely applications in the future. [ABSTRACT FROM AUTHOR]

CsPbX3 (X = Cl, Br or I) perovskite quantum dots (PQDs) have gained increasing interest due to their superior performance in photoelectric applications. In our work, a series of Mn2+ doped CsPbBr3 PQDs were successfully prepared in glasses by melt quenching and in situ crystallization technique. Due to the 4T1 (4G)→6A1 (6S) transition of Mn2+, a slight red shift from 510 nm to 516 nm was found, with the FWHM expansion from 18 nm to 26 nm. The PQDs@glasses showed excellent thermal stability, and the exciton binding energy reached a high level of 412 meV. The changes of the electronic structure after Mn doping CsPbBr3 can be demonstrated by first principles. Finally, a contactless electroluminescence device with the PQDs@glasses was designed based on the principle of electromagnetic induction, which is a potential application for detecting distance in sterile and dust−free environments. [ABSTRACT FROM AUTHOR]

Two-dimensional organic-inorganic hybrid Ruddlesden-Popper perovskites have attracted a lot of attention due to their unique photochemical properties and enhanced stability towards photoluminescence devices. Compared with three-dimensional materials, two-dimensional perovskites show great potential for photoelectric applications due to their tunable band gap, great excitation binding energy, and large crystal anisotropy. Although the synthesis and optical properties of BA 2 PbI 4 crystals have been extensively studied, the role of their microstructure in photoelectric applications, their electronic structure, and their electron-phonon interaction are still poorly understood. In this paper, based on the preparation of BA 2 PbI 4 crystals, the electronic structure, phonon dispersion, and vibrational properties of BA 2 PbI 4 crystals were revealed in detail with the help of density functional theory. The BA 2 PbI 4 stability diagram of formation enthalpy was calculated. The crystal structure of the BA 2 PbI 4 crystals was characterized and calculated with the aid of Rietveld refinement. A contactless fixed-point lighting device was designed based on the principle of an electromagnetic induction coil, and the points with different thicknesses of BA 2 PbI 4 crystal were tested. It is proved that the excitation peak of the bulk is 564 nm, and the surface luminescence peak is 520 nm. Phonon dispersion curves and the total and partial phonon densities of states have been calculated for the BA 2 PbI 4 crystals. The calculated results are in good agreement with the experimental Fourier infrared spectra. Besides the basic characterization of the BA 2 PbI 4 crystals, the photoelectrochemical properties of the materials were also studied, which further proves the excellent photoelectric properties of the BA 2 PbI 4 crystals and the broad application prospect.

CsPbX 3 (X = Cl, Br or I) perovskite quantum dots (PQDs) have gained increasing interest due to their superior performance in photoelectric applications. In our work, a series of Mn 2+ doped CsPbBr 3 PQDs were successfully prepared in glasses by melt quenching and in situ crystallization technique. Due to the 4 T 1 ( 4 G)→ 6 A 1 ( 6 S) transition of Mn 2+ , a slight red shift from 510 nm to 516 nm was found, with the FWHM expansion from 18 nm to 26 nm. The PQDs@glasses showed excellent thermal stability, and the exciton binding energy reached a high level of 412 meV. The changes of the electronic structure after Mn doping CsPbBr 3 can be demonstrated by first principles. Finally, a contactless electroluminescence device with the PQDs@glasses was designed based on the principle of electromagnetic induction, which is a potential application for detecting distance in sterile and dust-free environments.