High efficiency dye-sensitized solar cell based on novel TiO2 nanorod/nanoparticle bilayer electrode.

High light-to-energy conversion efficiency was achieved by applying novel TiO2 nanorod/nanoparticle (NR/NP) bilayer electrode in the N719 dye-sensitized solar cells. The short-circuit current density (J SC), the open-circuit voltage (V OC), the fill factor (FF), and the overall efficiency (η) were 14.45 mA/cm(2), 0.756 V, 0.65, and 7.1%, respectively. The single-crystalline TiO2 NRs with length 200-500 nm and diameter 30-50 nm were prepared by simple hydrothermal methods. The dye-sensitized solar cells with pure TiO2 NR and pure TiO2 NP electrodes showed only a lower light-to-electricity conversion efficiency of 4.4% and 5.8%, respectively, compared with single-crystalline TiO2 NRs. This can be attributed to the new NR/NP bilayer design that can possess the advantages of both building blocks, ie, the high surface area of NP aggregates and rapid electron transport rate and the light scattering effect of single-crystalline NRs.