Preparation And Properties Study Of TiO₂/CdSe Coupled Photoelectrode

With the increasing of fossil energy exhaustion, the development of new energy becomesthe world’s research hot spot. Photovoltaic power generation, as one of the important aspects ofthe use of solar energy, has raised extensive attention. In this paper, the working principle andclassification of solar cells were summarized, then the main research focuses on the preparationand performance testing and reseach of CdSe sensitized TiO₂photoelectrode. CdSenanoparticle（NP） thin-film, CdSe nanowire（NW） and TiO₂nanoparticle（NP） thin-film, TiO₂nanorod（NR） with different morphology and properties were prepared with different methods,with which the TiO₂/CdSe photoelectrodes were constructed. Then the performance of thesephotoelectrodes were tested, so as to get the optimal one. The main research contents and resultsare as follows:1. TiO₂thin films have been prepared on ITO conductive glass using spin coating method.After being annealed, CdSe was cyclic voltammetry（CV） electrochemical deposited on itssurface to form a single layer TiO₂（NP）/CdSe （NP） photoelectrode. Annealing on400degreescan obviously increase CdSe’s crystallinity, and improve the photoelectrochemical properties ofobtained photoelectrode. On basic of TiO₂/CdSe, the multilayer （TiO₂/CdSe）nstructures wereconstructed（including n=1,2,3,4）. The microstructures, photoelectrochemical properties andQE of multilayer TiO₂/CdSe structures were investigated. The results showed that the CdSe thinfilms were grown preferentially along the （111） direction. The thickness and UV-Vis absorbanceintensity of multilayer films increased with the increasing of layer number of TiO₂/CdSestructures. The results obtained from photoelectrochemistry measurement indicated that theoptimal photoelectrochemical current response and open-circuit voltage were obtained in abiolayer TiO₂/CdSe system, and therefore demonstrated the favorable photoelectrochemicalproperties. The multilayer （TiO₂/CdSe）nstructures were sensitive to light, and showed stablephotoelectric response. Contrast the TiO₂/CdSe electrode of different thickness withmultilayer （TiO₂/CdSe）nstructures, we found that the increase of the thickness of pure CdSe（NP）thin-film cannot achieve the effect of the （TiO₂/CdSe）2system. 2. CdSe nanowires were deposited on TiO₂（NP） thin-film by constant current densitymethod. The abtained CdSe nanowire’s band gap（Eg） is2.62, which indicates that the absorptionwavelength occurs blue shift. The morphology, optical and photoelectrochemical properties ofTiO₂/CdSe prepared under different times were researched. The results show that UV-Visabsorbance intensity and photoelectrochemical properties increased with increasing of depositiontime. The highest QE of all the samples reached14%.3. A simple hydrothermal method was used to prepare TiO₂NR arrays on FTO conductiveglass. The preparation parameters of hydrothermal was studied, which have influence on themorphology of obtained TiO₂NR. The final preparation parameters are determined as:0.16mltitanium butoxide,6ml deionized water,6ml concentrated hydrochloric acid （35%wt）, reactiontemperature150℃, reaction time2h. And thenon basic of TiO₂nanorod prepared in thiscondition, CdSe with different cycles was deposited through cyclic voltammetry. Theabsorption spectrum and photoelectrochemical properties were studied, which indicates that theoptimal sample has a photocurrent density of0.15mA, open circuit potential of0.53V and QEvalue of43.4%.4. CdSe nanowires were deposited on TiO₂nanorods by constant current density methodwith different time. The sample with the best photoelectrochemical property was obtained by5min’s deposition, whose photocurrent density is0.136mA, open circuit potential is0.48V andQE value is27%.5. Comparison between CdSe（NP） film deposited through CV on TiO₂（NP） film and TiO₂NR was made. The results show that with the increase of CdSe（NP） deposition thickness, TiO₂（NR） array is superior to TiO₂（NP） thin-film. In our experiment when deposition cycles are20and30, their photoelectrochemical properties exist little difference, TiO₂（NP） thin-film evenshows better performance. However, when deposition cycles are above40cycles, TiO₂nanorodarray show better photoelectrochemical properties.