Study On The Structure And Performance Of TiO₂Light Scattering Layer For Dye Sensitized Solar Cell

Dye-sensitized solar cell (DSSC) has been regarded as a contender for traditionalsilicon solar cell. With the simple preparation, low cost and non-polluting energy,DSSC have attracted widely attention. As the key component of DSSC, TiO2photoanode became a focus among the reaserches. According to the Mie theory,particles used as light scatters for DSSC should have a large size comparable to thewavelengths of visible light, and form an effective light scattering. This wouldeffectively enhance the light harvest efficiency, leading to the higher photo-generatedcurrent.250nm sized,650nm sized and1100nm sized TiO2spheres were synthetizedvia a sol-gel method by adjusting aging time, the amount of tetrabutyl titanate (TBT)and potassium chloride. The different-sized TiO2spheres were then used as scattersfor DSSC. From photocurrent-voltage curves, DSSC with250nm TiO2spheres asscatters showed the highest solar energy conversion efficiency, which was improvedby24.48%compared with that of DSSC with pure P25photoanode. Based on theanalysis of UV-Vis spectrum and dye adsorption, the effect of different-sized TiO2spheres on the photoelectric properties of the cells were studied. The results showedthat the improvement performance resulted from the enhanced scattering.However, dye adsorption is much less for these scattering particles due to theirmuch smaller surface area, which would severely lower the electron concentration.Thus, it is indispensable to develop photoanode materials that not only serve as lightscattering layer but also offer enough dye adsorption sites. Spherical anatase TiO2covered with nanospindles (SNS) were fabricated through a facile hydrothermaltreatment of precursors in the presence of ammonia. The precursors were synthesizedby controlling hydrolysis rate of TBT in ethanol. It was confirmed that the structureand morphology of the products can be controlled by adjusting hydrothermaltreatment conditions. Time dependent trails revealed the growth mechanism of SNS.Furthermore, photocurrent-potential curves showed that the solar cells fabricated withthe SNS collected after18h hydrothermal treatment exhibited the highest solarenergy conversion efficiency of6.4%. Based on the UV-Vis spectrum and dyeadsorption density analysis, the improved performance can be attributed to the enhanced scattering and increased active sites for dye loading. Therefore, the dualfunctions of light scattering and many active sites for dye loading make SNS superiorcandidates for DSSC.