Enhancement in Photovoltaic Characteristics of CdS/CdTe Heterojunction

Abstract

The polycrystalline p-type CdTe thin film was deposited to form a solar cell structure with n-type CdS thin film window layer. Material characterization of the deposited thin films were investigated by X-ray diffraction measurements and the preferred orientations were obtained along (111) direction at 2 theta congruent to 24 degrees and 2 theta congruent to 26.5 degrees for CdTe and CdS films, respectively. The optical behaviors were investigated according to the transmission spectrum and corresponding direct band gap values were found as 1.51 eV for CdTe and 2.22 eV for CdS thin films. The superstrate CdS/CdTe thin film heterostructure was investigated under the dark and illuminated current-voltage measurements. The heterostructure showed a photovoltaic behavior with the cell efficiency of % 1.4. The effects of the etching process on the photovoltaic behavior of CdS/CdTe thin film heterostructure were also discussed and the cell efficiency was enhanced as about % 1.6 eV.