Fabrication of Rb2TeI6 thin films for stable, lead-free perovskite photodetector via dry-processed approach

In the vacancy-ordered double perovskite group, rubidium tellurium iodide is a rarely studied material. In this paper, we report the fabrication of Rb2TeI6 thin film via a dry-processed approach. The process includes the chemical vapor deposition of the RbI film, followed by a thermal annealing treatment in TeI4 vapor. The film has a tetragonal structure with good morphology, high absorption coefficient (>105 cm−1 in the 280–620 nm wavelength range), and good stability in ambient air. A photodetector is fabricated by growing a 300 nm-thick Rb2TeI6 film on indium-doped tin oxide electrodes. The Rb2TeI6-based photodetector has 0.87 pA dark current at 5 V bias. Under 450 nm illumination, it shows 1.4 mA/W photoresponsivity, approximately 1010 J photodetectivity, and 16.4 ms/19.2 ms response times with an excellent operational stability. This study not only presents an effective technique for fabricating the Rb2TeI6 perovskite thin film, but also shows its potential for photodetector application.