Fully printable hole-conductor-free mesoscopic perovskite solar cells based on mesoporous anatase single crystals

Mesoporous anatase singe crystal provides a large surface area and less carrier traps as compared to polycrystals; however, it is generally prepared with a particle size in micrometers by a complex method; this hinders its application as electron transport materials (ETMs) for mesoscopic perovskite solar cells (MPSCs). Herein, we fabricated a small-sized mesoporous anatase single crystal with a large surface area (169 m(2) g(-1)) and an oliver-shape (about 120 nm in length and 60 nm in width) by a simple method and applied it as an ETM into a hole-conductor-free fully printable MPSC. As expected, a high-quality film was formed, and the device showed an obvious increase in efficiency as compared to the P25 (commercial TiO2)-based device due to the faster electron extraction from perovskite to the ETM. This suggests that the mesoporous anatase single crystal is a promising ETM candidate for producing efficient fully-printable hole-conductor-free MPSCs.