Optimizing TiO₂ Compact Electron Transport Layer for Perovskite Solar Cells

Perovskite Solar Cells (PSCs) have gained attention for photovoltaic energy generation due to their high-power conversion efficiency and low-cost fabrication. The Electron Transport Layer (ETL) is responsible for electron extraction and transport while blocking holes. Morphological defects in the ETL promote charge recombination, reducing device efficiency and stability. This work investigates the influence of spin-coating and spray-coating deposition of compact TiO₂ ETLs on charge transport in n-i-p PSCs. The films were characterized by optical and electrochemical techniques, and the results were correlated with photovoltaic performance. Spray-coated ETLs produced more compact and uniform films than spin-coated ones. Devices with spin-coated ETLs achieved an average power conversion efficiency (PCE) of 5.2%, while spray-coated ETLs reached 10.0%. These findings demonstrate that optimizing spray-coating deposition improves ETL quality and significantly enhances photovoltaic performance, highlighting the potential of this method as a scalable alternative for PSC fabrication.