Epitaxial Growth of Lead-Free 2D Cs3Cu2I5 Perovskites for High-Performance UV Photodetectors

The all-inorganic lead-free Cu-based halide perovskites represented by the Cs-Cu-I system, have sparked extensive interest recently due to their impressive photophysical characteristics. However, successive works on their potential application in light emission diodes and photodetectors rely on tiny polycrystals, in which the grain boundaries and defects may lead to the performance degradation of their embodied devices. Here, 2D all-inorganic perovskite Cs3Cu2I5 single crystals are epitaxially grown on mica substrates, with a thickness down to 10 nm. The strong blue emission of the Cs3Cu2I5 flakes may originate from the radiative transition of self-trapped excitons associated with a large Stocks shift and long (microsecond) decay time. Ultravioelt (UV) photodetectors based on individual Cs3Cu2I5 nanosheets are fabricated via a swift and etching-free dry transfer approach, which reveal a high responsivity of 3.78 A W-1 (270 nm, 5 V bias), as well as a fast response speed (tau(rise) approximate to 163 ms, tau(decay) approximate to 203 ms), outperforming congeneric UV sensors based on other 2D metal halide perovskites. This work therefore sheds light on the fabrication of green optoelectronic devices based on lead-free 2D perovskites, vital for the sustainable development of photoelectric technology.

Automated summary

The all-inorganic lead-free Cu-based halide perovskites have attracted extensive interest recently due to their impressive photophysical characteristics. In this study, 2D all-inorganic perovskite Cs3Cu2I5 single crystals were successfully grown on mica substrates, and UV photodetectors based on individual Cs3Cu2I5 nanosheets were fabricated, showing high responsivity and fast response speed, outperforming other 2D metal halide perovskite UV sensors. This work sheds light on the fabrication of green optoelectronic devices based on lead-free 2D perovskites, important for the sustainable development of photoelectric technology.