High-Efficiency All-Inorganic Perovskite Solar Cells Tailored by Scalable Rutile TiO₂ Nanorod Arrays with Excellent Stability

Tailored optimization of perovskite solar cells (PSCs) is a persistent objective to achieve the ultimate commercialization purpose, in which the electron/hole transport layer with thickness on the nanometer scale is generally required to maximize the charge collection and minimize the series resistance. Therefore, precise control on the fabrication technology of the charge transport layer is important. Herein, one-dimensional (1D) rutile TiO2 nanorod arrays with a thickness of 1.8 μm have been fabricated and employed as a potential electron extraction layer for high-efficiency all-inorganic CsPbBr3 PSCs for the first time. Arising from the sufficient carrier mobility, excellent conductivity, and superior charge extraction ability by means of regulating the donor concentration with nitrogen atoms, a champion efficiency of 8.50% has been achieved with excellent long-term stability after 50 days storage in air conditions, which is comparable to that of the 200 nm-thick TiO2 layer tailored device. The primary results demonstrate that the TiO2 layer with micrometer scale thickness is also feasible to effectively collect the photogenerated carriers and realize considerable solar-to-electric conversion ability, providing multifarious technologies to fabricate the electron extraction layer.