| Copper indium selenide (CuInSe2,CIS) based solar cells attract wide attention because of their high conversion efficiency, stable performance, good performance in low-light. They have the potential to occupy a place in the energy market in the future. However, there are some obstacles in commercialization of CIS-based solar cells; the electricity generation cost per watt of power is also higher than the traditional cost. It is necessary to develop less expensive techniques based on non-vacuum deposition technologies like electrodeposition or screen printing. Non-vacuum electrodeposition is considered to be a potential technique for large-scale low-cost preparation of CIS solar cells due to its advantages such as low equipment cost, high utilization of raw materials, low deposition temperature and high deposition rate. Although the single metal element deposition is relatively mature, electrodeposition is still very difficult for multiple compound semiconductor, and CIS is the ternary compounds, CIS deposition is more complex and difficult. Moreover, the reduction potential of Cu (Ⅱ), In (Ⅲ) and Se (Ⅳ) vary widely, so in actual deposition a number of factors need to be considered to make them to be deposited in the same potential, and to reach the required quality after appropriate annealing.Compared with the flat film, semiconductor nanowire radial pn junction solar cells have fundamental advantages due to their potential benefits in carrier transport, charge separation and light absorption. So even in the case of low crystalline quality materials, this structure is also designed to enable efficient collection of photogenerated carriers as possible, so that the feasibility is greatly increased using low-cost route (eg, electrodeposition). This thesis is divided into three parts, as follows:First, a low-cost electrodeposition-annealing process was investigated. The effects of component concentration in the solution, deposition voltage, solution PH value on the morphology and composition of one-step electrodeposited CIS films were systematically studied. CIS films with smooth surface, dense structure and composition close to stoichiometric CIS can be achieved using the condition of: concentration of In (Ⅲ) excess, Se (Ⅳ):Cu (Ⅱ) ratio of around 1.7, deposition potential of-0.5～0.65 V (vs.SCE). The selenization process and its reaction mechanism were studied, and the results showed that the crystalline quality of CIS film was improved as annealing temperature and ramp rate was increased, and Cu-Se compounds quantity was decreased. XRD and Raman results showed that the annealed CIS thin film had chalcopyrite tetragonal crystal structure; UV-VIS-NIR tests showed that the band gap of films was about 0.98 eV; C-V tests showed that carrier concentration was in the 1016～1017 cm-3 order of magnitude after annealing and KCN etching treatment. The solar cells with structure of AZO/i-ZnO/CdS/CIS/Mo/glass were fabricated using the annealed CIS film as absorber. The solar cell with an area of 0.20 cm2 had an energy conversion efficiency of 0.96%(open circuit voltage Voc=144 mV, short circuit current Jsc=24.4 mA/cm-2, fill factor FF=27.2%, conversion efficiency ofη=0.96%).The second part is the preparation of nano alumina template and a preliminary analysis of the mechanism of anodic oxidation process. In the experiment the AAO templates were prepared using two routes. AAO templates with long pore structure and highly ordered hole array were prepared using anodization of high purity aluminum foil; the other AAO templates were prepared on substrates by anodizing the aluminum film on substrates. By carefully controlling oxidation conditions, such as anodizing'voltage, electrolyte type and concentration, oxidation temperature and time, we can control the AAO template structure parameters, such as distance between adjacent hole centers (25～500 nm), hole diameter (10～400 nm), barrier thickness and length of pores (300 nm-100μm). These experiment and theoretical results were useful to preparation of copper indium selenium nanowires.The third part is preparation and characterization of the CIS nanowire arrays synthesized on substrates by electrodeposition using AAO as growth template. XRD, TEM measurements showed the CIS nanowires after annealing were chalcopyrite structure. CIS nanowires with good crystalline quality and component ratio close to stoichiometry of CIS can be prepared either annealed in vacuum or in selenium atmosphere conditions. UV-VIS-NIR spectra showed that the CIS nanowires had the band gap of 0.96 eV, close to the band gap of CIS bulk materials. The absorption, reflection and transmission properties of CIS naowire arrays were studied in detail. It was found in the CIS with the same amount of material, CIS nanowire arrays can absorb more light. The main reason is that nanowire arrays increased light scattering of light in the structure of the transmission path. There is a light trapping effect, which is beneficial to the solar cells. Electrical properties of a single nanowire was tested, the resistivity of the annealed nanowire with diameter of 300 nm was 37.5Ω·cm, slightly higher than that of CIS thin films. Finally, a principle CIS nanowire solar cell was fabricated with structure of CuInSe2/CdS/ZnO core-shell heterojunction structure. Optical-electrical test indicates that the structure has certain photoelectric effect. The cell performance can be further improved by reasonable treatment and passivation of the interface and optimizing the cell preparation process. These results provide theoretical and experimental basis for nanostructure solar cells.
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