Synthesis of Cs2SnI6 perovskite thin film by low-pressure chemical vapor deposition method

Abstract

Cs2SnI6 is an all-inorganic, air-stable and Pb-free halide perovskite material. In this work, we propose a low-pressure chemical vapor deposition method that enables the synthesis of continuous Cs2SnI6 thin films. Some technical parameters such as the deposition time and the deposition temperature of CsI were varied to investigate the morphology and thickness of Cs2SnI6 thin films. The film was further undergone an annealing treatment in SnI4 ambient to enhance characteristics, such as the long-term stability and the structural, optical and electrical properties. After annealing in SnI4, the film was found to be stable in ambient air (40–60% humidity) for 30 days. The film shows n-type semiconducting with an energy bandgap of 1.58 eV. Its absorption coefficient is higher than 3.4 × 104 cm−1 in the visible region with a maximum value of 0.9 × 105 cm−1 at the wavelength of 420 nm. The carrier concentration increased to 5.5 × 1017 cm−3, and the resistivity declined to 3.1 Ω.cm.