Preparation of c-TiO<sub>2</sub> films; Preparation of TiO<sub>2</sub>NSs films; SEM Images; J-V characteristic; Tables from Enhanced photovoltaic properties of perovskite solar cells by TiO<sub>2</sub> homogeneous hybrid structure

The c-TiO<sub>2</sub> films were deposited onto the clean FTO by chemical bath deposition (CBD) method with 0.06 M TiCl<sub>4</sub> aqueous solution at 70 ℃ for 30 min. The c-TiO<sub>2</sub> films were annealed at 450 ℃ for 30 min in ambient conditions.; TiO<sub>2</sub>NSs films were fabricated by a hydrothermal method; Fig. S1 Top-view images of TiO<sub>2</sub>NSs on FTO/c-TiO<sub>2</sub> prepared at 170 ℃ for (a) 1 h; (b) 2 h; (c) 3 h; (d) 4 h, the scale bar is 500nm. Fig. S3 (a) Top-view image of 7C TiO<sub>2</sub>NPs on FTO/c-TiO<sub>2</sub>; (b) the enlarged view of TiO<sub>2</sub>NPs; (c) cross-sectional SEM image of 7C TiO<sub>2</sub>NPs on FTO/c-TiO<sub>2</sub>.;Fig. S2 J-V characteristic of the lead iodide perovskite solar cells based on TiO<sub>2</sub>NSs films of different reaction time. Fig. S4 J-V characteristic of the lead iodide perovskite solar cells based on 3h TiO<sub>2</sub>NSs/7CNPs and 7C NPs films.; Table. S1 Photovoltaic Device Parameters of the TiO<sub>2</sub>NSs/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Solar Cells. Table. S2 Photovoltaic Device Parameters of the FTO/c-TiO<sub>2</sub>/TiO<sub>2</sub>NSs/NPs/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/HTM/Ag and FTO/c-TiO<sub>2</sub>/TiO<sub>2</sub>NPs/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/HTM/Ag Solar Cells.