Ultraviolet–Visible Photodetector Based on a Cs2TeI6 Thin Film

Te-based halide perovskites as alternatives to Pb-based halide perovskites have received increasing attention due to the advantages of nontoxicity and high stability. However, the investigation of utilizing Te-based halide perovskites to realize a broadband photoresponse photodetector (PD) is still rare. Herein, a Cs2TeI6 film is developed and used for achieving a high-performance PD. Optoelectronic performance analysis shows that the PD is sensitive to light in the ultraviolet (265 nm) to visible (570 nm) region. The responsivity, specific detectivity, and external quantum efficiency reached 48 mA/W, 4.8 × 1012 jones, and 13% at 420 nm and 12 mA/W, 1.2 × 1012 jones, and 5.64% at 265 nm, respectively, under 4 V bias and weak light intensity. The response time is 9 ms/125 ms at 420 nm. Moreover, the Cs2TeI6 PD can operate consistently for 500 cycles and shows less loss of performance after sixmonths in the atmospheric environment. This work verifies that Cs2TeI6 has good potential for ultraviolet–visible light detection.