Muhammad Amin Padhiar,Yongqiang Ji,Minqiang Wang,Shusheng Pan,Sayed Ali khan,Noor Zamin Khan,Lei Zhao,Fangrong Qin,Zhuan Zhao,Shaolin Zhang
Perovskite nanocrystals (NCs) feature adjustable bandgap, wide absorption range, and great color purity for robust perovskite optoelectronic applications. Nevertheless, the absence of lasting stability under continues energization, is still a major hurdle to the widespread use of NCs in commercial applications. In particular, the reactivity of red-emitting perovskites to environmental surroundings is more sensitive than that of their green counterparts. Here, we present a simple synthesis of ultrathin ZrO2 coated, Sr2+ doped CsPbBrI2 NCs. Introducing divalent Sr2+ may significantly eliminate Pb° surface traps, whereas ZrO2 encapsulation greatly improves environmental stability. The photoluminescence quantum yield of the Sr2+-doped CsPbBrI2/ZrO2 NCs was increased from 50.2% to 87.2% as a direct consequence of the efficient elimination of Pb° surface defects. Moreover, the thickness of the ZrO2 thin coating gives remarkable heat resistance and improved water stability. Combining CsPbSr0.3BrI2/ZrO2 NCs in a white light emitting diode (LED) with an excellent optical efficiency (100.08 lm W−1), high and a broad gamut 141% (NTSC) standard. This work offers a potential method to suppress Pb° traps by doping with Sr 2+and improves the performance of perovskite NCs by ultrathin coating structured ZrO2, consequently enabling their applicability in commercial optical displays.
Currently, there is a cyan gap in white light-emitting diodes (LEDs) manufactured by combining near-ultraviolet (NUV) chips with tricolour (blue/green/red) phosphors, resulting in a poor colour rendering index (Ra). Broadband blue-cyan phosphors contain blue, cyan and green luminescent components that complement the cyan gap. In this paper, feldspar-structured Ba 0.92- x Sr x Al 2 Si 2 O 8 :0.08Eu 2+ ( x = 0–0.5) phosphors were prepared by a high-temperature solid-phase method and a cation substitution strategy. A phase transition was achieved by varying the concentration of x , which resulted in the formation of two luminescent centres and a 10.33-fold enhancement of the luminescence intensity for Ba 0.92 Al 2 Si 2 O 8 :0.08Eu 2+ . The colour of the emission changed from the original green to blue-cyan, and the strongest emission peak with a half-height width of 94.5 nm was observed at a Sr 2+ concentration of 0.3 (30%) and covered the blue, cyan and green wavelength ranges (390–600 nm). The experimental value of the optical band of the substrate is 5.71 eV, and the luminous intensity of the Ba 0.62 Sr 0.3 Al 2 Si 2 O 8 :0.08Eu 2+ sample at 150 °C was 91.3% of that at room temperature. Ba 0.62 Sr 0.3 Al 2 Si 2 O 8 :0.08Eu 2+ , (Ca, Sr) AlSiN 3 :Eu 2+ and 365 nm NUV chips were successfully packaged into white LED devices. The colour rendering index (Ra) of the prepared white LED devices was 87, R9 was 89, the colour coordinates were (0.3763, 0.3382), and the colour temperature was 3759 K, which effectively solves the problem of the lack of cyan luminescent components in white LED devices and simplifies the manufacturing process of white LEDs.
Gaoqing Hang,Qiulei Li,Alberto José Fernández-Carrión,Sihao Deng,Lunhua He,Xiaojun Kuang,Xiaoyan Yang
Oxide-ion conductors based on tetrahedral anion-related oxides have attracted considerable attention due to their high oxygen-ion conductivity and potential applications in clean energy devices, such as solid-state fuel cells. In this study, we report the improvement of oxide-ion conductivity by Sr2+ doping in isolated tetrahedral zircon-type PrVO4. It is found that Pr0.975Sr0.025VO4−δ features the highest oxide-ion conductivity of 2.62 × 10–3 S·cm–1 at 800 °C under air, with an oxygen transport number of 0.93. The formation and stabilization of oxygen vacancy defects, as well as the oxide-ion migration mechanism in PrVO4, were investigated through combining experimental characterizations and computing simulations. The results indicate that the concentration of oxygen vacancy defects increases with Sr2+ substitution, and the vacancies are accommodated by the formation of corner-sharing V2O7 dimers. Oxygen-ion migration proceeds via a cooperative mechanism involving V2O7-dimer breaking and reforming assisted by synergistic rotation and deformation of neighboring VO4 tetrahedra. The results provide valuable insights for further investigation and optimization of zircon-type oxides as potential oxide-ion conductors for electrochemical devices.
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