| Dye-sensitized solar cell (DSC) is a new type of the photoelectrochemical solar cell. Because of its simple fabrication procedure, low cost, better stability and cleanliness, DSC has aroused world researches and application prospect. TiO2 is a n-type semiconductor with band gap of 3.2eV, and functional material with many unique physical and chemical properties. There are very important application in a great many areas as photocatalysis, environmental protection, efficient solar cell and so on. In particular, TiO2 has a wide field of application with good prospects in photovoltaic cell, and arouses great interest of people. TiO2 nanorod (NR) is a one-dimensional nanomaterials liking nanorod/ nanotube. Compared with the zero-dimensional nanoparticle, one-dimensional nanomaterials have large surface area and provide a natural channel for the rapid migration of the electronics, which make the electronic conductivity increased. Therefore there is a wide of application in the photovoltaic cell. In recent years, many scientists have done a lot of work in the preparation of TiO2 NR arrays and application of basic research.Hydrothermal method is a kind of reaction in autoclave with high pressure and temperature, The method usually makes insoluble or insoluble material dissolved using water as reaction medium. The recrystallization can be also carried out in the reaction. Hydrothermal technology has two characteristics, firstly, requiring relatively low temperature; Secondly, avoiding the components volatilizing in the presence of a closed container. In this thesis, TiO2 NRs array can be grown on the transparent conductive oxide (TCO) with bare and textured blocking layer (BL) by hydrothermal method, respectively. Titanium butoxide (TNBT) can be used as titanium source. The product can be analyzed and characterized applying X-ray powder diffraction (XRD), scanning electron microscopy (SEM). It is used as the anode of assembly DSC and carrier out testing research. Specific study as follows:(1)TiO2 NR arrays can be prepared successfully using hydrothermal. TiO2 NR arrays were grown on the TCO using TNBT, concentrated hydrochloric acid, deionized water, sodium chloride as raw materials. And the morphology and structure of TiO2 NR arrays are investigated through controlling reaction condition. The experimental results show that TiO2 NR arrays can be prepared better for hydrothermal reaction at 150℃in an oven for 15 h. These not only provide effective electronic transport channels, but also to some extent increase absorption and utilization for the incident photons so that enhancing the photoelectricity conversion efficiency of DSC. The testing results show that the open circuit voltage (Voc) and short-circuit current (Isc) were about 1.60 mA/cm2 and 0.67 V, respectively.(2)The BL can be design between TCO and TiO2 NR arrays, and the performance of DSC assembled is explored. The textured BL is prepared by calcining the film consisting of polystyrene (PS) spheres and TiO2 seed layer, and finally formed with TiO2 spherical shell structure, which increasing the roughness at the bottom of the TiO2 NR arrays, and enhancing dye adsorption in the process of cell sensitization. Thus, the utilization ratio of the incident light is improved and is useful for enhancing the DSC performance. This textured BL is mainly affected by sintering temperature, heating rate and soaking time. Higher temperature will lead to rupture of spherical shell structure, faster heating rate may cause textured BL crack, and reaction time mainly influences overall morphology and crystal formation on the BL. In short, a reasonable temperature and time is essential to design BL. Inhere we adopt 1℃/min as heating rate and 450℃as sintering temperature in order to form a good shell structure and build a good basis for follow-up study. In order to better show the role of the textured BL, we also have designed a single BL with only TiO2 seed layer. Experimental results show that in the presence of the textured BL, Voc and Isc of DSC are increased in varying degrees, about 3.87 mA/cm2 and 0.86 V, while Voc and Isc were only 2.35 mA/cm2 and 0.71 V in the role of BL with a single TiO2 seed layer, respectively. Also compared with the performance of TiO2 DSC assembled without BL, it can be seen that the textured BL can effectively improve bottom roughness, increasing the dye attached and enhance the utilization rate of incident light in order to improve Voc and Isc of DSC. And we further study the relation between different spherical shell diameter of the textured BL and the current-voltage (I-V) characteristic curves, so that the better textured BL with suitable shell diameter can be obtained and the bottom roughness is able to be increased as soon as possible. Finally, the transmission spectrum can be compared between TCO coating textured BL and a single TCO, the results show that the TCO with textured BL significantly increases the transmittance of incident light, so that the highly efficient use of the incident light is achieved. In short, the photoelectric performance of TiO2 NR arrays assembled DSC, to some degree, is improved by introducing the textured BL. |
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