Tin fluoride assisted growth of air stable perovskite derivative Cs2SnI6 thin film as a hole transport layer

Dye sensitized solar cells are promising low-cost and environmentally friendly alternatives to conventional semiconductor solar cells. However, the use of liquid electrolytes containing the iodide/tri-iodide redox couple causes long-term problems such as electrode corrosion and electrolyte leakage. Here we report the facile low-temperature solution approach to fabricate the perovskite derivative Cs2SnI6 thin film as an alternative hole conductor for solid state dye sensitized solar cells under ambient air condition. Impact of the addition of tin fluoride (SnF2) on the crystalline structure, morphology and optoelectronic properties of cesium-tin-iodide thin films was investigated. The absorbance spectrum exhibited a band gap value of 1.27 eV of semiconducting Cs2SnI6 perovskite derivative. Hall Effect measurement showed the improved mobility of SnF2 treated Cs2SnI6 thin films. The 10% SnF2 treated Cs2SnI6 thin films achieved the highest mobility with the value of 468.1 cm2.V−1.s−1. These findings demonstrated the suitability of perovskite derivative Cs2SnI6 thin film as a hole transport layer as well as a promising light harvesting layer for solar cell applications.