Characterization of ti02 based dye-sensitized solar cell prepared by screen printing method.
Musila, Nicholas Muendo
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The dye-sensitized solar cell can provide an economically credible alternative in mitigating the challenges presented by the current convectional photo voltaic devices. They use appropriate semiconductor materials to produce electricity. Whereas the semiconductor assume both the task of light absorption and charge carrier transport, the two functions are separated. Light is absorbed by a sensitizer which is anchored to the surface of a wide band semiconductor. Charge separation takes place at the interface via photo-induced electron injection from the dye into the conduction band of the semiconductor. Carriers are transported in the conduction band of the semiconductor to the charge collector. This research aimed at contributing to the foregoing research on characterization of low cost Ti02 based dye sensitized solar cells. To achieve that, black berry dye was used as the electron donating species. Blackberry dye was extracted from blackberry fruit, purified using methanol, water and acetic acid in a ratio of 4:5:1 and adsorbed onto a nano-porous titania substrate. The nano-porous Ti02 was prepared by mixing Ti02 powder with de-ionized water, propanol and acetic acid in the ratio of 8:16:11. Its layer was mounted on a conductive glass substrate by using screen printing technique. Using DUV3700 spectrophotometer, the Ti02 layer was characterized to obtain its optical properties which were transmittance and reflectance. Carbon coated glass was used as the counter electrode. An electrolyte solution was used as the redox couple. This solution was made of potassium iodide saturated with iodine. For the optical properties, it was found out that as the film thickness increases, the transmission of light through the film decreased from 55% for 129.00nm thick film to 25% for the 158.11 nm thick film. The solar cell parameters were determined as a way of characterizing the solar cell. The open circuit voltage was found to be 420 mV for the solar cell with the smallest thickness (129.00nm) and 380 mV for the thickest DSSC (158.1125nm). The short circuit current obtained was 118 j.lA and 87.7 ~lA for the thinnest and the thickest DSSCs, respectively. The fill factor was between 45.89 % and 55.83 % for the cells fabricated. The measured solar cell efficiencies ranged between 0.2832 % and 0.5124 %.