Efficient Metal Halide Perovskite Solar Cells Prepared by Reproducible Electrospray Coating on Vertically Aligned TiO2 Nanorod Electrodes.

Vertically aligned TiO2 nanorod (NR) electrodes with straight macropores enabled a metal halide perovskite (MHP) solution to be fully infiltrated within their structure and, as a result, formed void-free dense MHP films reproducibly during an electrospray-coating process, whereas conventional mesoporous TiO2 (m-TiO2) electrodes with three-dimensionally interconnected mesopores formed internal voids by imperfect infiltration of MHP solution. Hence, TiO2 NR-based MHP solar cells could be more reproducibly fabricated by an electrospray-coating process and exhibited smaller current density-voltage hysteresis with respect to the scan direction and scan rate than the m-TiO2-based MHP solar cells due to the short and straight electron pathway either by a one-dimensional TiO2 NR electrode or a densely formed MHP layer within the TiO2 NR electrode.