Ultrasonically sprayed indium sulfide buffer layers for Cu(In,Ga)(S,Se)2 thin-film solar cells

Indium sulfide layers were grown by an ultrasonic spray pyrolysis method for application in Cu(In,Ga)(S,Se)2 solar cells. X-ray diffraction measurements of layers on soda lime glass showed polycrystalline In2S3 with preferential orientation along the [103] direction and X-ray photoelectron spectroscopy revealed presence or absence of oxygen and chlorine impurities depending on the composition of the spray solution. For more quantitative chemical composition measurements In2S3 layers were sprayed on silicon substrates and analyzed with Rutherford backscattering spectrometry. The structural and chemical information on the In2S3 layer sprayed with different sulfur concentrations in the chemical precursor solution are correlated to the photovoltaic performance of solar cells. Best cell efficiency of 12.4% was achieved with an ultrasonically sprayed In2S3 buffer layer on a Cu(In,Ga)(S,Se)2 absorber.