Hollow TiO2 spheres as mesoporous layer for better efficiency and stability of perovskite solar cells

Highlights: • Hollow TiO₂ synthesized by template method shows diameters about 200 nm, along with shell thickness about 30 nm. • The perovskite films fabricated on the hollow TiO₂ demonstrate good morphology and crystallinity, resulting in better scattering light ability and fewer defects. • PCE of cells based on hollow TiO₂ can reach 17.60%, which is 14% higher than that based on conventional TiO₂. • The PSCs based on hollow TiO₂ demonstrate better stability under ambient atmosphere with a relative humidity of 65 ± 5% for 30 days. -- Abstract: Hollow TiO₂ spheres were synthesized by template method, with the diameters was 200 nm and the thickness of shell about 30 nm. The high-quality perovskite films fabricated on the hollow TiO₂ mesoporous layer demonstrate smooth surface and large grain size, resulting in the better scattering light ability and fewer defects. The efficiency of the perovskite solar cells prepared on hollow mesoporous layer can reach 17.60%, which is an approximately 14% higher than the PCE of conventional mesoporous layer devices under the same condition. Importantly, the solar cells with hollow TiO₂ can exhibit better stability than the cells with mesoporous TiO₂ after aging 30 days in 65% relative humidity under dark conditions. The results indicate that the hollow TiO₂ mesoporous layer will be a candidate for better efficient and stable CH₃NH₃PbI₃ perovskite solar cells, and this structure provides a direction for the design of novel mesoporous layers for perovskite solar cells in future.