Correlation between defect properties and the performance of eco-friendly CsSnI₃-based perovskite solar cells

Abstract

This study investigates the potential use of eco-friendly, all-inorganic CsSnI3 perovskite (PVK) as an absorber layer. Despite having higher temperature stability of CsSnI3,the challenge is to get a uniform and defect-free film that hinders the performance. To accomplish this goal, we investigated several PSC performance-related variables, including material defect density (Nt), transport materials, layer thickness, temperature impacts, and back contact work functions. TiO2 demonstrates the best performances as ETL and PEDOT:PSS as HTL. Negative valence band or conduction band offset values indicate no barrier preventing photogenerated carriers from flowing into the charge transport layers. The simulation result shows that HTL thickness shows a higher impact than ETL thickness. For the PVK thickness of 500 nm and a carrier density of 1018 cm−3, the device offers an optimum PCE of 20.1 %. The PVK defect significantly impacts performance more than the interface defect. Higher recombination occurs at the TiO2-CsSnI3 interface. Defects in the deep-level trap (DLT) at the middle of the band gap energy are detrimental to device performance. The proposed structure's temperature coefficient (CT) is approximately ‒0.367 % K‒1, indicating excellent thermal stability in an open environment. Selection of 'A' cation, addition of additives, or carefully controlled fabrication technique can passivate the defect. This research shows the strategy for creating defects-free perovskite solar cell devices, ultimately enhancing performance and stability.