CsCu₂I₃ Nanoribbons on Various Substrates for UV Photodetectors

Cesium copper (I) halides, as a lead-free halide material system, have shown great potential in optoelectronic devices due to their environmental friendliness, high quantum efficiency, and extraordinary air stability. However, most of the previous reports are on quantum dots, bulk crystals, or free-standing wires. It is still challenging to realize the in-plane growth of one-dimensional (1D) cesium copper (I) halides on various substrates, which is essential for nanodevices with high integration density. Herein, we report the planar growth of CsCu₂I₃ nanoribbons (NBs) with high-quality single crystals on diverse substrates through a spatial-confined method. The in situ investigation of the growth process reveals that the morphology evolution of the NBs is controlled by both thermodynamics and kinetics that are dependent on the local supersaturation near the NBs. The CsCu₂I₃ NB-based photodetectors (PDs) exhibit an outstanding ultraviolet (UV) detection performance with a high responsivity (0.27 A/W), a specific detectivity (6.38 × 10⁸ Jones), and a fast photoresponse speed (t_rise/t_decay = 5.8/6.0 ms). Furthermore, the PDs exhibit high stability to light illumination and excellent flexibility to bending. The direct in-plane growth of the lead-free CsCu₂I₃ NBs on various substrates would promote the practical application of copper (I) halides in electronics and optoelectronics.