Efficient perovskite solar cells based on novel three-dimensional TiO₂ network architectures

Mesoscopic lead halide perovskite solar cells typically use TiO₂ nanoparticle films as the scaffolds for electron-transport pathway and perovskite deposition. Here, we demonstrate that swelling-induced mesoporous block copolymers can be templates for producing three-dimensional TiO₂ networks by combining the atomic layer deposition technique. Thickness adjustable TiO₂ network is an excellent alternative scaffold material for efficient perovskite solar cells. Our best performing cells using such a 270 nm thick template have achieved a high efficiency of 12.5 % with pristine poly-3-hexylthiophene as a hole transport material. The high performance is attributed to the direct transport pathway and high absorption of scaffolds, small leakage current and largely reduced recombination rate at interfaces. The results show that TiO₂ network architecture is a promising scaffold for mesoscopic perovskite solar cells.