Zero-Dimension (0D) lead halide perovskite nanocrystals (NCs) have attracted a sight of interest in the field of optoelectronic devices due to their outstanding properties, such as high photoluminescence quantum yield (PLQY), size- and composition-controlled tunable emission wavelengths. However, the toxicity of lead (Pb) element in the lead perovskite NCs is the bottleneck for the commercial application of perovskite NCs. Herein, we report a facile ligand–assisted synthesis to achieve lead-free Cs3Cu2Cl5 NCs with high PLQY of ~70% and good stability against environmental oxygen/moisture as a promising down-conversion material. It has good merits of high PLQY and large Stokes Shift (~300 nm) originated from the effect of Jahn-Teller distortion and self-trapped excitons (STEs). Furthermore, the Cs3Cu2Cl5 NCs embedded composite films (NCCFs) were utilized to enhance the ultraviolet (UV) response of silicon (Si) photodetectors. External quantum efficiency (EQE) measurements show that the UV response can be greatly improved from 3.3% to 19.9% @ 295 nm based on NCCFs combined with Si photodiodes. Our work offers an effective approach to develop highly efficient and stable lead-free Cs3Cu2Cl5 NCs for the application in the solar-blind UV photodetector.

中文翻译：

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能量下转换Cs3Cu2Cl5纳米晶体以提高UV光电探测器的效率

零维（0D）卤化钙钛矿铅纳米晶体（NCs）由于其出色的特性（例如高光致发光量子产率（PLQY），尺寸和成分控制的可调发射波长）而在光电器件领域引起了人们的关注。但是，钙钛矿型铅NCs中铅（Pb）元素的毒性是钙钛矿型NCs商业应用的瓶颈。本文中，我们报道了一种简便的配体辅助合成方法，可实现无铅Cs3Cu2Cl5 NCs，PLQY约为70％，并且对环境氧/水分具有良好的稳定性，是一种很有前途的下转换材料。它具有较高的PLQY和较大的斯托克斯位移（〜300 nm）等优点，其源于Jahn-Teller畸变和自陷激子（STEs）的影响。此外，Cs3Cu2Cl5 NCs嵌入式复合膜（NCCF）用于增强硅（Si）光电探测器的紫外线（UV）响应。外部量子效率（EQE）测量表明，基于NCCF和Si光电二极管的结合，在295 nm下，UV响应可以从3.3％大大提高到19.9％。我们的工作为开发高效，稳定的无铅Cs3Cu2Cl5 NC提供了一种有效的方法，可用于日盲UV光电探测器。