Key Laboratory of Polar Materials and Devices (MOE) and Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Department of Electronic Engineering, East China Normal University, Shanghai 200241, China.
Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China and Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Nanoscale. 2019 Dec 21;11(47):22899-22906. doi: 10.1039/c9nr07096f. Epub 2019 Nov 25.
All-inorganic perovskite CsPbBr-CsPbBr composite nanocrystals (NCs) were synthesized via a convenient solution process without inert gas protection and systematically studied as green phosphors for light emitting diode (LED) applications. While colloidal composite NCs emit green color with an emission peak at around 515 nm, their thin films on top of blue GaN chips exhibit a redshift of ∼15-20 nm due to subsequential aggregation in solid state. The Commission Internationale De I'eclairage (CIE) chromaticity coordinates of the green LEDs assembled by composite NCs reached (0.201, 0.746) with nearly 100% green ratio. Moreover, the pure green LED displayed a luminous efficiency of 45 lm W under 10 mA driving current. The colloidal CsPbBr-CsPbBr composite NCs have the photoluminescence quantum yield (PLQY) as high as 74%. The high PLQY originates from cubic CsPbBr NCs well passivated by the zero-dimensional CsPbBr matrix, substantially suppressing the nonradiative recombination. The comparison between the green LEDs fabricated with pure and composite perovskites imply that the CsPbBr-CsPbBr composites with higher quantum yield could be an effective way to get the brightness and the stability of pure green LEDs.
全无机钙钛矿 CsPbBr-CsPbBr 复合纳米晶体（NCs）通过一种无需惰性气体保护的简便溶液法合成，并作为用于发光二极管（LED）应用的绿色荧光粉进行了系统研究。虽然胶体复合 NCs 发出的颜色为绿色，发射峰在 515nm 左右，但由于在固态中随后发生聚集，其在蓝色 GaN 芯片上的薄膜会发生约 15-20nm 的红移。由复合 NCs 组装的绿色 LED 的国际照明委员会（CIE）色度坐标达到（0.201，0.746），具有近 100%的绿色比例。此外，在 10mA 驱动电流下，纯绿色 LED 的光效为 45lmW。胶体 CsPbBr-CsPbBr 复合 NCs 的光致发光量子产率（PLQY）高达 74%。高 PLQY 源于被零维 CsPbBr 基质良好钝化的立方 CsPbBr NCs，大大抑制了非辐射复合。用纯和复合钙钛矿制成的绿色 LED 的比较表明，具有更高量子产率的 CsPbBr-CsPbBr 复合材料可能是获得纯绿色 LED 的亮度和稳定性的有效方法。
