MULTIJUNCTION PHOTOLVOLTAIC CELL PHOTOGENERATED CURRENT DENSITY CHARACTERIZATION TROUGH SPECTRAL IRRADIANCE MEASURES

Abstract

This study aimed to compare the behavior of the photo generated current of a multijunction solar cell (MJ), determined from measurements of spectral irradiance and the spectral response provided by the manufacturer with their experimental measurements of short circuit current to validate equivalence between these parameters and to define the junction responsible for limiting the electrical current established in the cell from the evaluation of the ratio between the currents generated (r_c) for the top and intermediate junctions. Therefore, spectral measurements were performed by using a spectroradiometer for reading spectral range which is between 300 nm and 1050 nm. The cell used for the experiments MJ has three junctions composed of indium gallium phosphide (InGaP) layer on top, indium gallium arsenide (InGaAs) in the intermediate layer and germanium (Ge) at the base with a total area of 1.0 cm², but with a coating resulting from the fingers of approximately 19. 5%, according to microscopic observation it structure. Thus, through irradiance measurements between 200 W/m² and 1200 W/m², approximately, it was observed that the methodology used to compare the behavior of the photo generated current and short circuit, in function of the global irradiance, valid the equivalence of these parameters, with capacity for generating 0.142 A / W and 0.141A / W, respectively. Furthermore, sets the intermediate junction InGaAs subcell as limiting the generation of current to the spectra obtained, as in all measures r_c > 1.