Study On Microstructures And Properties Of SnS And CdS Thin Film For Solar Cells

Tin monosulfide is a direct band gap semiconductor material with a band-gap of 1.3~1.5 eV, which is very close to the best band gap(1.5 eV) of solar cell. The optical absorption coefficient of SnS is very large( >104 cm-1), making it very suitable for the absorbing layer of solar cell. Because of low cost, absence of toxicity, and good abundance in nature, it has broad prospects in the field of thin film solar cells.Cadmium sulfide is also a direct band gap semiconductor material with a band-gap of 2.4 eV. Cadmium sulfide is of high light transmittance, to ensure that more photons are absorbed by the absorbing layer of solar cell. Also, the high conductivity of the Cadmium sulfide helps to reduce the resistance of solar cell, So that the cadmium sulfide is suitable for the window layer of solar cell.There is a close relationship between the properties of solar cell and the quality of thin film. So, electro-deposition technique is used to produce tin monosulfide thin film, and the influence of technical parameters to phase constitution, surface morphology and optical properties of tin monosulfide thin film is also studied. The processing parameters of preparing tin monosulfide thin film are 0.5mA/cm2 of current density, 10 mM Sn2+, Sn2+/S2O32-=1/5, 5 mM EDTA, pH=2, at 45 oC for 1.5h and annealled in argon gas at 300 oC. The deposited films are Stoichiometric, uniform and dense, with high opticala bsorption coefficient.Cadmium sulfide thin films are prepared by Chemical Bath Deposition method, and the influence of technical parameters to phase constitution, surface morphology and optical properties of cadmium sulfide thin film is also studied. The Processing parameters of preparing cadmium sulfide thin film are 0.015 M thiourea, 0.015 M cadmium chloride, 0.03 M ammonium chloride, pH=10, at 80 oC for 30 min and annealled in argon gas at 300 oC. The deposited films are Stoichiometric, uniform and dense, having a clear orientation in the(002) direction, with high light transmittance.CdS/SnS solar cell is prepared, and its properties are studied. The J-V curves show that the solar cell has obvious rectification property, while the photoresponse is weak.