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The Modification and Photoelectrochemical Properties of Nanostructured TiO2 Electrodes

Author: WangJiChao
Tutor: YangShuMing
School: Xinyang Normal University
Course: Applied Chemistry
Keywords: Dye-sensitized solar cells TBP Surface modification Electrochemical Photoelectrochemical
CLC: O614.411
Type: Master's thesis
Year: 2011
Downloads: 95
Quote: 0
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Abstract


With the rapid development of human industrial civilization, coal, oil, natural gas and other mineral resources are increasingly depleted. Worldwide increasingly tight energy supply, energy issues will become important factors restricting the economic development of countries. As alternative energy for fossil energy, solar energy has the most prospects of the development and use of more and more attention has been paid. Among the effective utilization of solar energy, the solar cells is the fastest growing in recent years, the most dynamic area of ??research. Dye-sensitized nanocrystalline thin film solar cells developed in the 1990s because of its simple preparation, low cost, high photoelectric conversion rate, etc., to become one of the hot spots of photoelectric conversion device. The dye-sensitized nanocrystalline solar cells by semiconductor nanocrystals film electrolyte, photoelectric sensitive agent and electrodes, the various components are an important influence on the performance of photovoltaic solar cells. The ways and means of the thesis, starting from these two aspects of the semiconductor nanocrystal film and electrolyte, and research to improve the photoelectric conversion efficiency of solar cells. 1 in the dye-sensitized solar cell, the electrolyte plays the role of the transfer of electrons and holes. Wherein the types of additives on the performance of the battery has an important influence, TBP, and Li is the commonly used additives. TBP band structure of nanocrystalline TiO2 electrode surface states the Applied Spectroscopy electrochemical method for determination of the of nanocrystalline Ti02 electrode in the electrolyte containing 4 - tert-butyl pyridine (TBP) flat band potential (Efb) . TBP on the the nanocrystalline YiO2 band structure of the electrodes has a significant impact. Excluding and containing 0.2 or 0.4 mol the L-1TBP of 0.2 mol · L-1 perchloric acid tetrabutylammonium (TBAP) / acetonitrile, measured TiO2 electrode Efb order of -2.25, -2.46 and - 2.60V. When added to Li, the TiO2 electrode Efb positive shift. The measured in the contain and containing 0.2 or 0.4mol · L-1TBP 0.2 mol L-1LiClO4 / acetonitrile TiO2 electrode Efb order of -1.12, -1.22 and-1.30V. Time-resolved current method of determination of the distribution of trap states. Excluding and containing 0.2 or 0.4mol · L-1TBP 0.2 mol · L-1 TBAP / acetonitrile, measured the TiO2 electrode trap state density of 3.52 × 1016,3.18 × 1016 and 3.37 × 1016cm-2, distribution of trap states maximum at -1.99, -1.89, and -1.85 V at. Li added to further reduce the density of trap states. Excluding containing 0.2 or 0.4mol · L-1TBP 0.2 mol · L-1 LiClO4 / acetonitrile measured the TiO2 electrode trap density of states in turn is 8.39 × 1015,1.11 × 1016 and 9.22 × 1015 cm-2 trap state distribution of the maximum at -0.72, -0.84 and-0.95V at. Finally, we study the photoelectrochemical properties of N3 dye-sensitized nanocrystalline TiO2 electrode in an electrolyte solution containing different concentrations of TBP. The experimental results show that, with increasing TBP concentration, Voc increases, so that the increase in photoelectric conversion efficiency of the TiO2 electrode. 2 by surface modification to improve the performance of dye-sensitized nanocrystalline TiO2 thin film photovoltaic solar cells. Because the nano-structured surface of the semiconductor electrode and electrolyte between the lack of a depletion layer, the electrons are easily injected into the semiconductor conduction band of the charge recombination occurs with the electrolyte in the oxidizing substances, which is a major factor in restricting the dye-sensitized solar cell conversion efficiency Therefore, to reduce the charge recombination becomes critical to improve the photoelectric conversion efficiency of the battery. In this paper, we use a simple method Nanocrystalline TiO2 electrode modified SrCO3 and BaSO4 layer, by means of infrared analysis proved the presence of SrCO3, and BaSO4 modification layer and SrCO3 and BaSO4 modification of thickness of the nanocrystalline TiO2 electrode Electrochemical and photoelectrochemical performance. The results show that, SrCO3 and BaSO4 modification layer flatband potential has little effect on Nanocrystalline TiO2 electrode modified significantly reduce the trap density of states. The experiments show that, to obtain good photoelectric performance optimization SrCO3 and BaSO4 modified layer thickness. The the N3 sensitized modified layer SrCO3 nanocrystalline TiO2 solar cell photoelectric conversion efficiency value in under the 100mW/cm2 white light reaches the maximum of 7.46%. The value of the N3 sensitized modified two-story BaSO4 nano-crystalline TiO2 thin film solar cells photoelectric conversion efficiency in under the 100mW/cm2 white light maximum to 7.56%, an increase of about 6% photoelectric efficiency than pure TiO2 electrode. Paper we use a simple method in the N3-sensitized nanocrystalline TiO2 electrode surface modified BaSO4 layer, using analytical tools to prove the existence of Nanocrystalline TiO2 electrode surface BaSO4. We also study the impact of BaSO4 modified layer thickness on the electrochemical and photoelectrochemical performance. BaSO4 modified layer on the N3-sensitized nanocrystalline TiO2 electrode of flatband potential Efb the spectroelectrochemical methods. Experimental results show that the BaSO4 modified electrode with the unmodified electrode modified Efb substantially no change. Using the after BaSO4 Modified, the concentration of the surface states of the electrode is reduced. We also study the the BaSO4 modification N3-sensitized nanocrystalline TiO2 electrode photoelectrochemical performance, the results show that the modified two-story BaSO4 layer of N3 sensitized nanocrystalline TiO2 thin film solar cells in the white light of 100mW/cm2 photoelectric conversion efficiency a maximum of 7.40%.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section Ⅳ group metal elements and their compounds > The titanium Vice family ( IV B group metal elements) > Ti Ti
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