Optoelectronic Application Of TiO₂Nanotube Arrays Prepared By Anodic Oxidation

Solar energy is the most effective way to solve the energy shortage and environmentalpollution. Restricted to the reflectance of cell surface and the limiting band gap of semiconductor,photoelectric conversion efficiency has a large room to improve. In this thesis, it prepared the TiO2nanotube arrays, which has a high transmissivity for visible and near-infrared light, and strongabsorption of ultraviolet light, and has an important application in the anti-reflection film of solarcells. In order to overcome the limitation of semiconductor band gap, and to response a broadersolar spectrum, the thesis explored synergistic effect mechanism combined infrared with ultravioletunder the dual-mode excitation. Also the composite material of photo-luminescent material andTiO2nanotubes is prepared and analyzed in the application of solar cells.The thesis offers a new synergistic enhancement effect theory combine down-conversion andup-conversion simultaneously, which can be effective to increase the utilization of the high-energyphotons and low-energy photons for semiconductor solar cells. Based on the above analysis, thethesis select two frequency conversion materials with synergistic effect property as case, andanalyze the application value in solar cell. The BaSr2Y6O12: Er3+phosphor and Er3+-Ca2+co-dopedAl2O3phosphor are prepared by solid phase method and precipitation method, respectively. Asynergistic effect phenomenon is found, which shows the red emission intensity under351nm and1540nm dual-excitation is4.7%time stronger than the sum of red emission intensities under the351nm and1540nm single excitation in BaSr2Y6O12: Er3+phosphor; Similarly, the synergisticenhancement rate of red emission under385nm and1540nm dual-mode excitation is3.9%inEr3+-Ca2+co-doped Al2O3phosphor. This phenomenon is attributed to the4I13/2and4I11/2levels ofEr3+from non-radiative transition process under the351nm/385nm excitation are excited again to4F9/2level by absorbing1540nm photon in the351nm/385nm and1540nm dual-excitation process.Highly-ordered TiO2nanotube arrays are studied by electrochemical anodization in differentorganic/water electrolyte solution, the TiO2nanotube array structure parameters as function of theelectrolyte composition is analyzed and characterized by scanning electron microscopy(SEM).Additionally, the growth mechanism of nanotube arrays is formed through the morphology of thedifferent growth stage, and the different morphology and size nanotube arrays are prepared byadjusting oxidation voltage, gained the law between nanotubes and oxidation voltage.The nano fluorescent material with high photo-luminescent properties is prepared, and the composite material of nano fluorescent material-TiO2nanotube array is assembled through the staticphase deposition method, thus a multifunction material of antireflection properties andphoto-luminescent properties is synthesized, and discussed the application value in the field of solarcell.