Efficient Inverted Perovskite Solar Cells Utilizing Inorganic Composite Multiple Electron Transport Layers

Electron transport layers (ETLs) featuring optimal film coverage and favorable electronic properties play a critical role in high-performance perovskite solar cells (PSCs). In contrast to organic ETLs, which have high material costs, inorganic metal oxide ETLs are considered promising alternatives for efficient inverted PSCs because of their low cost, high carrier mobility, and excellent stability. However, fabricating high-quality top inorganic ETLs that preserve the active perovskite layer remains a challenge. Herein, a composite electron transport bilayer comprising atomically coherent interfaced tin dioxide (SnO₂) nanoparticles and tungsten-doped zinc oxide (WZO) is introduced, which further facilitates charge extraction and mitigates detrimental interfacial deprotonation reactions. The tungsten doping ratio can be precisely controlled by adjusting the co-evaporation parameters. The results reveal that tungsten enhances charge extraction by fine-tuning the energy levels, whereas the SnO₂ layer simultaneously passivates the perovskite/ETL interface defects and inhibits deprotonation reactions. Utilizing this inorganic composite multiple architecture, a record efficiency of 23.19% is achieved for inverted PSCs with an all-inorganic ETL. This cost-effective approach provides a viable pathway for industrial-scale production of high-performance PSCs.