Effect of solvents on the growth of TiO2 nanorods and their perovskite solar cells

TiO 2 nanorods were synthesized by hydrothermal methods with ethanol-HCl and water-HCl solutions, respectively, and CH 3 NH 3 PbI 3− x Cl x perovskite solar cells based on them were fabricated. The power conversion efficiency (PCE) of the best solar cells based on TiO 2 nanorods with water-HCl solution is higher than that with ethanol-HCl solution. The dimensions, morphology, optical properties, and photogenerated charge behavior of the two kinds of samples were investigated. The results indicate that the better performance of solar cells based on TiO 2 nanorods with water-HCl solution than those with ethanol-HCl solution could be attributed to their special orientation, high conductivity, improved morphology, good optical properties, fast charge transfer and reduced charge recombination. A PCE of 11.8% was achieved using TiO 2 nanorods with water-HCl solution, which is the highest among the reported TiO 2 nanorod based cells. The PCE of cells based on TiO 2 NRs (w) (11.8%) is higher than those based on TiO 2 NRs (e) (8.6%), which is the highest among the reported TiO 2 NR based cells.