| Wide band gap materials ZnO and TiO2 have been received extensive attention due to their simple fabrication processes, excellent photoelectric and environment-friendly properties. It is easy to fabricate crystalline and transparent ZnO or TiO2 nano-structures under low temperature. The ZnO or TiO2 nano-structures have good stabilities at room temperature, and their bandgaps could be easily tuned by doping, which made them have extensive applications and developments in the photoelectric area. This dissertation mainly explored the synthesizing of ZnO and TiO2 nanostructures by hydrothermal method and their applications in the photoelectric devices.The experiments data revealed that the morphology of the ZnO nanorods synthesized via hydrothermal method was sensitive to some parameters during the growing process, for example, the diameter versus the solution concentration, the length versus the growing time and the verticality versus the crystallinty degree of the ZnO seed layer, etc. These characters enable us to design specific ZnO nanorods morphology according our requirements, i. e. controllable growth.The rough and large specific surface area ZnO nanorods were fabricated by hydrothermal methods, which were used to enhance the performance of the WO3 electrochromic devices. To fabricate this device, the amorphous WO3 layer was deposited on the ZnO nanorods via Pulse laser deposition (PLD) method, and the porous TiO2 layer was used as the counter electrode. The coloring time and the bleaching time of the device were characterized as 4.2 s and 4.0 s, respectively. The transparencies of the device under colored state and bleached state were 7% and 48 %, respectively. The device had good stability and its electrochromic efficiency at the wavelength of 650 nm was calculated as 118.6 C-1 cm, which is much higher than the device without ZnO nanorods.The hydrothermal process based ZnO nanorods were also used to improve the efficiency of the inverted organic solar cells. The ZnO nanorods arrays with lengths of ～120 nm and diameters of～10 nm were grown on ITO glasses, which were used as the cathodes of the inverted organic solar cell. With the lengths and the diameters of the ZnO nanorods on the orders of～100 nm and～10nm, respectively, as the electron transporting layer and hole blocking layer, could efficaciously decrease the carrier-recombination in the P3HT:PCBM layer. The EQE of the ZnO nanorods based device inverted organic solar cell could be increased to 57.6% along with the maximum photoelectric transformation efficiency of 2.15% with optimized MoO3 thickness.Meanwhile, we also carried out the work on the dye-sensitized solar cells using TiO2 as the photo anodes. By focusing on the device structures, we fabricated the bifacial solar cells using Pt nano-particle coated stainless steel meshes as the counter electrode. The experiments revealed that the efficiencies of front radiation and back radiation were characterized as 7.93% and 7.64%, respectively, with the devices using Pt/AM as the counter electrodes. For the first time, we reported the ratio of efficiencies for back and front side irradiation increased over 1. A I-/I3 concentration distribution model has been introduced to explain the advantages of back side irradiation in a bifacial DSSC. |
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