Ultraviolet detection and imaging of one-dimensional cesium copper iodine single crystals synthesized by gradient crystallization.

The small size and large trap density have seriously hindered the application of cesium copper iodine single crystals (SCs). Herein, we propose a strategy for synthesizing high-quality and large-sized CsCu₂I₃ SCs by gradient crystallization. The as-synthesized CsCu₂I₃ SCs exhibit a large length of 1.7 cm with a low trap density of 4.17 × 10⁹ cm⁻³. Moreover, such CsCu₂I₃ SCs show excellent photoelectric response to ultraviolet (UV) irradiation, owing to their high absorption coefficient, large Stokes shift, and one-dimensional electronic structure. The measured responsivity and detectivity of the CsCu₂I₃ SC-based photodetectors reach the maxima of 24.58 A/W and 1.02 × 10¹³ Jones, respectively, under 365 nm light irradiation. Due to the outstanding UV detection performance, such photodetectors are also utilized for achieving direct UV imaging with high resolutions. [ABSTRACT FROM AUTHOR]