Short-length and high-density TiO2 nanorod arrays for the efficient charge separation interface in perovskite solar cells

Abstract

The TiO2 nanorod arrays with the length of 70nm, the diameter of 20nm, and the areal density of 1000µm−2 were firstly prepared by the hydrothermal method using the aqueous grown solution of 38mM titanium isopropoxide and 6M hydrochloric acid at 170°C for 60min. Over-500nm-thickness CH3NH3PbI3−xBrx absorber layers were successfully obtained by sequential deposition routes using 1.7M PbI2·DMSO complex precursor solution and 0.465M isopropanol solution of the methylammonium halide mixture with the molar ratio of CH3NH3I/CH3NH3Br=85/15. The perovskite solar cells based on the TiO2 nanorod array and 560nm-thickness CH3NH3PbI3−xBrx absorber layer exhibited the best photoelectric conversion efficiency (PCE) of 15.93%, while the corresponding planar perovskite solar cells without the TiO2 nanorod array and with 530nm-thickness CH3NH3PbI3−xBrx absorber layer gave the best PCE of 12.82% at the relative humidity of 50–54%.