Low-dimensional metal halide perovskites have been widely regarded due to their unique crystal structure and photophysical properties. Herein, blue-emission CsPbBr₃ quantum dots (QDs) or nanocrystals (NCs) with extremely small crystal size (1–2 nm) but high photoluminescence quantum yield (PLQY, 72.4%) are synthesized with a new surface ligand, single (6-amino-6-deoxy) beta cyclodextrin (6A-βCD), which also acts as the confined-growth template for such small QDs. Detailed photoluminescence spectrum and femtosecond transient absorption spectrum study proves that the blue emission with multiple peaks originates from both band-edge radiation and exciton recombination. Furthermore, as a result of the small size, exciton localization in the form of self-trapped excitons (STEs) and significant quantum size confinement effect are both important reasons for the efficient and wide blue emissions of these QDs. This work provides a new strategy not only to synthesize ultrasmall perovskite QDs but also to develop blue perovskite-QD light-emitting devices.

中文翻译：

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具有明亮和宽蓝色发射的超小型 CsPbBr3 量子点

低维金属卤化物钙钛矿由于其独特的晶体结构和光物理性质而受到广泛关注。在此，蓝色发射 CsPbBr ₃具有极小晶体尺寸 (1-2 nm) 但光致发光量子产率 (PLQY, 72.4%) 的量子点 (QD) 或纳米晶体 (NC) 与新的表面配体合成，单（6-氨基-6-脱氧） β 环糊精 (6A-βCD)，也可作为这种小量子点的限制生长模板。详细的光致发光光谱和飞秒瞬态吸收光谱研究证明，具有多个峰的蓝色发射来源于带边辐射和激子复合。此外，由于尺寸小，自陷激子 (STE) 形式的激子局域化和显着的量子尺寸限制效应都是这些 QD 高效和宽蓝色发射的重要原因。