| Zinc oxide(ZnO) is a novel Ⅱ-Ⅵ compound semiconductor with a hexagonal wurtzite structure. ZnO can be described as a number of alternating planes composed of tetrahedrally coordinated O2- and Zn2+ ions, stacked alternately along the c-axis, which result in the ZnO with piezoelectric and pyroelectric property. ZnO is an important oxide semiconductor with wide band-gap of 3.37 eV at room temperature that is suitable for short wavelength optoelectronic applications. The high exciton binding energy is about 60 eV, which can ensure efficiency excitonic emission at room temperature. ZnO is transparent to visible light and can be made highly conductive by doping. So it can be used as transparent conductive electrode and window layer in thin film silicon solar cells. Especially ZnO nanostructures are more successtually to be synthesized and ZnO nanostructures have promising potentials in nano optoelectronic devices, Moreover, ZnO is a nontoxic, low-cost, abundant material. So the ZnO is a material with important research value. In this paper, we synthesized the ZnO nanostructures on the stainless steel mesh by hydrothermal and chemical vapor deposition(CVD) route, and studied their optical and wettability properties. In addition, the influence of sputtering power, substrate temperature and hydrogen doping ratio on the electrical properties of the as grown aluminum-doped zinc oxide(AZO) films through radio frequency magnetron sputtering was carried out. And the effect of light trapping structure of AZO on the performance of silion solar cells was also studied. The main contents are as follows:(1) In modern society, there is a growing need for the effective separation of water and oil because of the increasing oil pollution. But the traditional water and oil separation technology have many drawbacks, such as low separation efficienct, high operation costs. In order to overcome these drawbacks, materials with both superhydrophobic and superoleophilic properties have received considerable attension in recent years.Through the low temperature hydrothermal route, stainless steel mesh coated by Al film was dipped in a capped Pyrex glass bottle filled with zinc nitrate hydrate and hexamethyleneteramine at 90 ℃ for 2 h. The ZnO nanoflake arrays were grown on the stainless steel mesh. The photoluminescence(PL) spectrum of room temperature showed that the crystallization of ZnO nanoflake arrays should be gradually improved with increase of the growth time. At last, the coated mesh was immersed into the ethanol solutions for 10 h. The water contact angle on the coated mesh is about 156°, the oil contact angle is about 0°,and the oil can easily penetrate the coated mesh. A detailed investation showed that the special hierarchical rough structure and the appropriate size of the mesh played an important role in obtaining the superhydrophobicity and superoleophilicity. The coated mesh has best superhydrophobicity when the size of the stainless steel mesh is 75 μm. In the separation experiments, we used four kinds of water and oil mixture. The separation efficiency of diesel and water has the peak value of 95.3%.(2) Superhydrophobicity(superoleophobicity) and superoleophilicity(superhydrophilicity) only is a single wettability surface. Reversible wettability transition between superhydrophobic and superhydrophilic on the materials surface has interesting application potential in widely different sciences and technologies. Through the chemical vapor deposition route, large area ZnO nanorod arrays were synthesized successfully on the stainless steel mesh coated by Au film. ZnO nanorod arrays have uniform arrangement and highly c-axis orientation. The PL spectrum showed that the ctystal quality of ZnO nanowires depended on the wire radius. The water contact angle on the coated mesh is about 157°after it was stored in the dark for 2 weeks. However, the coated mesh shows superhydrophilicity and the water contact angle became 0°after ultraviolet(UV) irradiation, and water can easily penetrate the coated mesh. The reversible wettability switching between superhydrophobocity and superdrophilicity is observed by alternation of UV irraditation and dark storage. Because the ZnO is photoresponsive materials, water molecules were easily adsorbed on the oxygen vacancy sites after UV irraditation, which lead to the superdrophilicity. The hydroxyl groups can be replaced gradually by oxygen atoms when the coated mesh is put in the dark. The coated can also be used in the separation water and oil, the separation efficiency for diesel can reach to 97%. Moreover, dense and vertically aligned ZnO nanorods array with a large area is fabricated by simple two-step process on the Al substrate. Compared with the ZnO nanorod arrays on the stainless steel mesh, the ZnO nanorod arrays on the Al substrate has better morphology and shorter wettability transformation time.(3) Through magnetron sputtering, AZO transparent conductive films were deposited on the glass substrate. The result showed that the AZO film has lowest resistivity and Square resistance when the sputtering temperature、sputtering power、hydrogen doping ration are 300 ℃、200 W、8%, respectively. The transmittance of the thin film surpasses 85% in the visible region. Light trapping structure in silicon thin film solar cells can scatter the incident light, increase the optical path, and improve the efficiency of solar cells. The 2 μm thick Al layer were deposited on the glass substrate, followed by anodization in phosphoric acid and critic acid under the applied voltages 195 V and 40 V to obtain porous AAO(anodic aluminum oxide) with two different diameters on the glasses. Then the glasses with porous AAO were subjected to wet chemical etching in 40% hydrofluoric acid solution for 10 s. So we successfully get the glass substrate with rough structure. The efficiency of the n-i-p solar sells on the rough glass which was formed in phosphoric acid was improved from 4.57% to 5.03% compared to flat glass substrate. In addition, the transmittance of the rough glass substrate with AZO deposition was more than 80% and without slightly lower than flat glass. |
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