Er⁺³ Doped TiO₂ Based Dye-sensitized Electrode Performance Of Solar Cells

The worldwide demand for energy is expected to double by the year 2050 and triple by the end of the century. An abundant supply of energy is necessary for global political, economic and environmental stability. There is growing concern, however, that the production of oil will soon not be able to keep up with thegrowing demand leading to dire economic consequences. In addition, the combustion of fossil fuels has been implicated in anthropogenic global warming, which is predicted to produce widespread environmental damage. The development of carbon-free sources of energy that are scalable to meet increasing societal demands is therefore one of the major scientific challenges of this century.Light from the sun is arguably the ideal source of energy. The solar flux striking the earth contains 10 000 times the average global power usage, and is the largest single source of clean energy which is readily available. While technologies have been developed to harness solar energy efficiently, they are not yet an economically viable alternative to fossil fuels. The abundant supply and environmental friendliness of solar energy make the efficient and cost-effective conversion of solar radiation into electricity a compelling scientific goal.During the past decade, dye-sensitized solar cells (DSSCs) have attracted much attention as low-cost alternatives to conventional inorganic photovoltaic devices. The mesoscopic TiO2 film texture in these cells significantly increases the cross section for surface-anchored light-harvesters while maintaining a good contact with electrolytes. In these devices, photon-to-electricity conversion is achieved by ultrafast electron- injection from a photoexcited dye into the conduction band of TiO2 and subsequently dye regeneration and hole transportation to the counter electrode. An impressive 10.4% solar-to-electric power conversion efficiency has been achieved with a DSSC. However, the achievement of long-term stability, which is an important requirement for the application of DSCs, has become a major challenge for a long time。In this paper, the different preparation method of the optical-anode electrode of semiconductor titanium dioxide, the making process of the DSSCs was shown, the relations between the photoelectric properties and the semiconductor. Adding a mirror at the back of the Pt electrode affect the photoelectric properties in the performance testing process of DSSCs, the components of the electrolyte, the performance of the DSSCs between doping the Er2O3 and not doping Er2O3 in the TiO2 electrode were studied. The best photoelectrical conversion efficiency is obtained 6.05%.1. The TiO2 film was obtained by doctor blade method.TiO2 slurry was prepared by stirring the mixture of TiO2 powder(P25), ethanol,dispersant acetylacetone and Triton X-100. Then the slurry was scraped on the conductive glass plate. The TiO2 film was heated at 450℃for 450 min to remove some impurities and produce nanoporous. TiO2/dye electrode was fabricated by soaking in 0.3g/L N3 dye solution for 24 h. The Pt counter electrode was prepared by thermal decomposition method. The cell was assembled by dropping an electrolyte solution into the space between the TiO2/dye electrode and the counter electrode. Then a mirror is added at the back of the counter electrode so as to enhance the optical absorption in the process that the performance test was carried on electrochemical workstation CHI660, therefore the efficiency of the cells is increased.2. 20-nm-Sized TiO2 was prepared by hydro-thermal method. TiO2 slurry was prepared by stirring the mixture of TiO2,ethanol,dispersant acetylace- tone, Triton X-100 and Er2O3. Then the slurry was scraped on the conductive glass plate. The TiO2 film was heated at 500℃for 500 min to remove some impurities and produce nanoporous. TiO2/dye electrode was fabricated by soaking in N719(5.5×10-5 M)dye solution for 24 h. The energy conversion efficiency for TiO2-doped-Er2O3 is obtained form 4.83% to 6.05% under AM = 1.5 .3. I studied the factors for influencing the performance of the DSSCs, such as the anneal temperature,keeping time in the dye solution, TiCl4 treatment of the TiO2 film,the composition of the electrolyte,adding or not adding a mirror at the back of the counter electrdes of the cells, mixed or not mixed Er2O3 in the TiO2 electrode.the results show that there are better photoelectric properties under the condition of annealing at 500℃for 500 min,TiCl4 treating for 30min at the temperature of 80℃, immersed in the N719 solution(5×10-5M)for 24 h.Under the irradiation of 100mW/cm2 by simulated solar light, the photoelectric conversion efficiency of the DSSC with the active surface was 6.05%, the open circurt voltage and the short circuit current were 739mV , 23.67 mA/cm2 respectively.