A 200-nm length TiO2 nanorod array with a diameter of 13 nm and areal density of 1100 μm-2 for efficient perovskite solar cells

Rutile TiO2 nanorod arrays with lengths of 200 nm, 490 nm and 800 nm were prepared by a hydrothermal method using an aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 degrees C for 75 mM, 105 min and 115 min, respectively. CH3NH3PbI3-xBrx, thin films were obtained by two-step sequential deposition using a 1.7 M PbI2 center dot DMSO complex precursor solution and a 0.465 M isopropanol solution of a methylammonium halide mixture with a molar ratio of CH3NH3I/CH3NH3Br = 85/15. The influence of the microstructure of the TiO2 nanorod array on the charge separation at the perovskite/TiO2 interface and the photovoltaic performance of the corresponding solar cells were investigated. Perovskite solar cells based on a 200-nm length TiO2 nanorod array with a diameter of 13 nm and areal density of 1100 mu m(-2) exhibited the best photoelectric conversion efficiency (PCE) of 16.23%, with an open-circuit voltage (V-oc) of 1.02 V, short-circuit photocurrent density (J(sc)) of 21.98 mA cm(-2) and fill factor (FF) of 0.72, as well as an average PCE of 15.63 +/- 0.60%, with a V-oc of 1.00 +/- 0.03 V, J(sc) of 21.80 +/- 0.81 mA cm(-2) and FF of 0.71 +/- 0.02 under illumination of simulated AM 1.5 sunlight (100 mA cm(-2)).