Large area bar coated TiO2 electron transport layers for perovskite solar cells with excellent performance homogeneity

• Bar coating of conformally covered uniform large area TiO 2 electron transport layers. • Utilization of bar coated TiO 2 for perovskite solar cells (PSCs), for the first time. • Demonstration of PSCs with high efficiency and reduced hysteresis . • Highly reproducible PSCs with excellent performance homogeneity on large area. Perovskite solar cells (PSCs) are the potential futuristic renewable energy technologies for solar energy conversion with their rapid rise in efficiencies. Towards realizing large scale PSCs, this work presents an economic, sustainable and scalable bar coating with high throughput for electron transport layers (ETL) on 50 mm × 50 mm substrates. Bar coating is systematically engineered to obtain conformally covered compact TiO 2 on FTO glass followed by mesoporous layer of desired thickness. For a fair evaluation, spin coated TiO 2 on similar size substrates are compared. Optical and photoluminescence analyses unveil greater homogeneity of bar coated ETL over spin coated counterparts. PSCs on bar coated ETL exhibit comparable efficiencies with good reproducibility and reduced hysteresis compared to conventional spin coated ETL devices. Photovoltaic performance homogeneity on larger substrates is significantly higher for bar coated ETL devices than the spin coated ones. The study provides scalable, sustainable and appropriately engineered bar coating technique for TiO 2 on larger substrates, which are demonstrated in high performance PSCs thereby indicating the practical implications towards the fabrication of perovskite solar modules.