Solution-synthesized SnO₂ nanorod arrays for highly stable and efficient perovskite solar cells

We report a simple and low-cost approach to enhance the longstanding stability of the perovskite solar cell (PSC) through the application of low-temperature grown SnO₂ nanorod (NR) arrays. SnO₂ NR arrays were fabricated by an aqueous synthesis method in the presence of hydrochloric acid and using thin compact SnO₂ as seeds. The influence of HCl concentration on the photovoltaic (PV) performance of the SnO₂ NR array based PSC device was investigated. The formed crystalline SnO₂ nanorods with square transversal-sections were oriented on the FTO facets in a well-defined and perpendicular fashion at an optimal HCl concentration. The optimized width and length for SnO₂ nanorods were 30 nm and 150 nm, respectively. Consequently, efficient and stable SnO₂ nanorod based perovskite devices were obtained with an average power conversion efficiency (PCE) of 16.57%. The SnO₂ nanorod array based PSCs demonstrated considerably better ultraviolet (UV) and ambient air stability than the planar SnO₂ and notably mesoporous TiO₂ solar cells. This paper provides a prospective scheme to grow high-quality three-dimensional SnO₂ nanorod arrays for highly stable and efficient PSCs.