Unveiling Non-Fullerene Routes: Strategic Design of Wide Bandgap Inverted Perovskite Solar Cells with SnO2 Layers

Recently, metal halide perovskites have garnered attention in photovoltaic research, experiencing a substantial increase in efficiency, achieving an impressive 26.1%. Within this realm, the inverted perovskite solar cell structure is notable for avoiding stability issues associated with the transport layer, such as Spiro-MeOTAD in regular perovskite solar cells. However, to date, the majority of high-efficiency inverted structures employ fullerene derivatives like C60 and PCBM as Electron Transport Layers (ETLs), posing difficulties in commercialization due to their long-term stability and cost-related challenges. Consequently, inorganic materials like SnO₂, TiO₂, and Nb₂O₅ have emerged as potential ETL candidates, with SnO2 being the most extensively used material in n-i-p structures due to its high electron mobility, wide bandgap, and low cost.<br/><br/>We report achieving a high efficiency of 18.3% at a 1.77eV bandgap, utilizing synthesized SnO2 nanoparticles, dispersed in a non-damaging solvent, as an Electron Transport Layer (ETL) in an inverted structure. This efficiency is the highest achieved using SnO2 in inverted structures, even without considering the bandgap. In order to mitigate defects originating from the expanded SnO2 surface area attributed to the small particles, ethylenediamine (EDA) was employed for passivation. Notably, EDA exhibited a bifunctional role between the perovskite and SnO2 layers. In order to validate this, observations of a reduction in defects and an enhancement in charge transportation between the perovskite/SnO2 interfaces will be conducted, utilizing Photoluminescence (PL) and X-ray Photoelectron Spectroscopy (XPS) analytical techniques.