Study On Conversion Oflighttoelectricity Of Nanocrystalline TiO₂ Films Doped Moified By Dyestuff

What's important in studying photoelectrochemical flat cell on dye-sensitized is choosing light-to-electricity material and investigating photo-to-electron conversion mechanism. But the cell is low in photo-to-electron conversion efficiency (IPCE), which does not make practical application feasible. After much data and information are collected, a photoelectrochemical cell on dye-sensitizing nanocrystalline TiO2 film is developed. The experiments show that multi-layers of a charge-transfer dye to sensitize the film for light harvesting don't increase IPCE, which is because we do not improve IPCE and light harvesting efficiency (LHE) at the same time. It is a factor that restricts development of the photoelectrochemical cell on dye-sensited before nanocrystalline semiconductor electrode comes. Because nanoparticle has lots of strange characteristics and electron transferring mechanism of the cell on dye-sensitizing nanocrystalline TiO2 is different from that of the photoelectrochemical flat cell, new electron transferring mechanism comes up. (1)The nanocrystalline TiO2 film is prepared by sol-gel and appearance of the film is observed by SEM. The X-ray graph shows the film has lots of anatase and a few rutile TiO2, but does not have brookite TiO2. The average diameter of particle is 25nm according to Scherrer formula. The Isc is in line with Iinc and slope is 1.41 on testing characteristic of light-to-electron. Voc is in line with LnIsc. So we may think the nanocrystalline TiO2 film electrode accords with Voc-Isc characteristicof semiconductor Schottky barrier in photoeletrochemical cell and we obtain that the ideal factor (n) is 1.89. At the same time, we find photocurrent of reverse side is more than that of front side.(2)The nanocrystalline TiO2 film is sensitized by dyestuff with dip and absorption. The electronic coupling is established between dyestuff and nanocrystalline film because of interaction of absorbing functional of dyestuff and nanocrystalline and so electron is injected to conduction band of TiO2 from excited state of dyestuff. On testing photocurrent-photovoltage curve, we attain that Voc is 0.56,Isc is 18.27mA/cm2,ff is 40.9% and Eff is 6.93%. (3)The TiO2 film is doped by metallic ion with sol-gel. On testing photoelectric properties, we find the photocurrent of the film doped by Zn2+ or Cd2+ is more than that of pure TiO2 film. This is because they are semiconductor themselves and form electron-hole pair. At the same time, the velocity of forming electron-hole pair is more than that of complex and so the photocurrent increases. Through experiments, we affirm that the solar cell on dye-sensitized nanocrystalline TiO2 film is realistic...