Polyethyleneimine-Assisted SnO₂ Electron Transport Layers for Roll-to-Roll Processed Perovskite Solar Cells

Perovskite solar cells (PSCs) have garnered significant attention as promising candidates for the next generation of solar energy-harvesting devices. Despite their impressive efficiency potential, conventional fabrication methods, such as spin-coating, have limitations in terms of scalability for large-scale production. To address this challenge, the roll-to-roll (R2R) process has emerged as a commendable approach for the cost-effective and high-throughput manufacturing of PSCs. In this research article, we propose electron transport layer (ETL) engineering as a strategy to enhance the performance of R2R-processed PSCs. Specifically, we introduce polyethyleneimine (PEI) as a dispersant within the ETL and systematically optimize the PEI concentration to achieve improved uniformity and bandgap control. Through systematic experimentation, we demonstrate that the optimal PEI concentration (1 wt%) leads to a perovskite solar cell with a power conversion efficiency (PCE) of 15.8%. In addition, the solar cell device with the optimized ETL recorded a stable efficiency of 15.8% even in MPPT measurement.