Optimizing thickness of tin oxide electron transporting layer to reduce hysteresis in carbon-based perovskite solar cells

Abstract

Tin oxide (SnO2) is frequently chosen as an electron transport layer (ETL) in perovskite solar cells (PSCs) owing to its outstanding electron transport properties. Nevertheless, the thickness of the ETL significantly influences hysteresis behavior of PCSs. To address this issue, tin (II) 2-ethylhexanoate in 2-methoxyethanol (2-MOE) was employed as the precursor solution for SnO2 ETL preparation. We systematically varied its concentrations from 0.2 M to 1.0 M to optimize the film thickness. Our findings indicate that the PSC with a SnO2 film deposited from a 0.6 M precursor concentration achieved the highest power conversion efficiency (PCE) of 13.51% and the lowest hysteresis index (HI) of 0.54. Furthermore, we explored the impact of film thickness on hysteresis behaviour and provided a comprehensive analysis. Based on the experiment, it was observed that the thickness of the film has an impact on the presence of defects and interfacial charge transfer, which could contribute to the occurrence of HI. This study offers valuable insights into the development of alternative ETLs suitable for large-scale PSC production.