Characterization of cdxsel_xs/cu2sp-n junction for solar cell application deposited by chemical bath deposition method
Njeru, Ephantus Nyaga
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The rapid growth in technology has led to a very high demand for renewable sources of energy which can be accessed by everyone irrespective of one's locality. CdS has so far proved to be a good window material when matched with CU2Sas an absorber material of the P-N junction for solar cell application. This research entails the doping of the Cadmium sulphide with selenium so as to enhance optoelectric properties. Cd-Set.sS films will be deposited using the CBD method. Chemicals to be used for this are; solutions of pure ammonium nitrate, thiourea, sodium selenosulphate and cadmium nitrate. Solutions of 0.004M cadmium nitrate, 0.008M ammonium nitrate, and 0.008M thiuorea in deionised water will be prepared, stirred till all the particles are dissolved and 20m1of each solution will be taken into a separate beaker. Doping of the CdxSel-xS films will be done by varying volumes of uniform concentration of sodium selenosulphate (Na2SeS03) solutions by volume at a constant deposition temperature of 80°c. The best value of x realised will be maintained as the deposition temperature is varied from 60°c to 90°c. Deposition of CU2Sfilm on a glass substrate will require the following Chemicals; copper sulphate, hydrochloric acid, thiourea, and tartaric acid solutions of analytical grade. At a constant temperature of 80°C, deposition of CU2Sfilms will be done as follows; 25mL of copper sulphate will be complexed with 25ml of O.2M tartaric acid in a beaker, and then 25ml of 0.2M thiourea will be mixed in it with constant stirring. The pH will be adjusted to 3 by addition of dilute hydrochloric acid with constant stirring using the pH meter. The cleaned glass substrate will be immersed vertically into a beaker and the deposition process will be carried out at different solution concentrations of CUS04 in order to determine the optimum conditions for the deposition of Cu2S thin films. The best concentration of CuS04 will be maintained as the deposition temperature is varied from 60°c to 90°c. The optical analysis of the thin films deposited above will be done using UVVIS NIR 3700 spectrometer while the sheet resistivity will be done using the four point probe method. Optical properties like reflectance and transmittance measured using UVVIS NIR 3700 spectrophotometer will be used to calculate others optical properties like band gap (Eg), refractive index (n), extinction coefficient (k) and absorbance (a). The results will be analysed to determine how optical conductance, transmittance, absorbance and the electrical resistivity varies with the conditions of deposition using the Scout software. Finally the optimal values of CdxSel-xS and CU2S will be used to fabricate (CdxSel_XS/CU2S)P-N junction for solar cell application. The solar cell P-N junction will be characterized using the solar celJ simulator to find it's I-V characteristics and parameters like fill factor (FF), conversion efficiency (11), and open circuit voltage (V00)'