Optical Characterization of Compounds for Dye-Sensitized Solar Cell Applications
Njoroge, W. K.
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The dye Sensitized solar cell can provide an economically credible alternative in miugaring the challenges presented by the current convectional photovoltaic devices. Whereas the se m iconductor assume both the task of light absorption and charge carrier transport, the two functions are separated Light is absorbed b~. a sensitizer \\ hich 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 charve collector The use of sensitizers in conjunction with oxide films of nano crystallme morphology has :1 broad :;bs')f])ti0n band and permits to harvest a large fraction of sunlight Nearly quantitative conversion of incident photon into electric current is achieved over a large spectral range extending from the UV ill the ncar l f< region. Overall solar energy to electrical energy conversion efficiencies of over 10% has bee n reported III addition, there are good prospects to produce these cells at lower cost than conventional solar cells The aim of this research is to contribute to the optical characterization of compounds required 111 TiO: based dye sensitized solar cells. To achieve this, several dyes will be used as the electron donating species These dyes will be adsorbed onto a nano-porous titania substrate. The nano-porous TiO: will he' prepared by sol-gel process and its layer will be mounted on a glass substrate bv ernp lov ing scree n printing technique. Using DUV3700 spectrophotometer the TiOc layer will be charac terize d to obtain iio. optical prope n ies which are transmittance and reflectance when in both un-sensiuzed and sens ii ized. An l ,'I:; e lccuolvte solution will be used as the redox couple. This solution \\ill be made of potassium iodide saturated "ith iodine. The solar cell parameters wil l then be determined as a \\'3\ of characterizing tht' solar cell. Thev will include open circuit voltage (Voc), short circuit current (l sc ). fill factor IFFI. efficiencv (Ill and power at maximum power point (Pl1laJ of the solar cell. Finallv , comparison 311(1 appropriate conclusions will be made as to which type ofDSSC is the best as per the dyes used