AUTHOR=Liu Chengjun , Wang Lixi , Fang Fan , Zhao Zihan , Pan Jiangyong , Akram Javed , Shafie Suhaidi Bin , Talaighil Razika Zair , Li Qing , Zhao Zhiwei , Wu Jun , Zhu Zhuoya , Lei Wei , Zhang Xiaobing , Chen Jing 

TITLE=Energy Down-Conversion Cs3Cu2Cl5 Nanocrystals for Boosting the Efficiency of UV Photodetector

JOURNAL=Frontiers in Materials

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.682833

DOI=10.3389/fmats.2021.682833

ISSN=2296-8016

ABSTRACT=<p>Zero-dimension (0-D) 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) and 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 Cs<sub>3</sub>Cu<sub>2</sub>Cl<sub>5</sub> NCs with a 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 Cs<sub>3</sub>Cu<sub>2</sub>Cl<sub>5</sub> 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 Cs<sub>3</sub>Cu<sub>2</sub>Cl<sub>5</sub> NCs for the application in the solar-blind UV photodetector.</p>