Comparison of theoretical efficiencies of three and four layer multijunction solar cell and the effects of varying the bottom layer material

This paper represents a comparison of theoretical efficiencies of three and four layer multijunction solar cell and the effects of varying the bottom layer material. Different types of solar cell models are mentioned here. The equations used for the calculations along with the material parameters are given. Total five materials of compound semiconductor with direct and indirect band gap are considered for making various combination of multijunction solar cell model. In this paper, four multijunction solar cell models have been considered. Model 1 is GaInP2/GaAs/Ge, model 2 is GaInP2/GaAs/GaAs0.91Bi0.0857, model 3 is GaInP2/GaAs/GaAs0.94Bi0.0583/GaAs0.91Bi0.0857, model 4 is GaInP2/GaAs/ GaAs0.94Bi0.0583/Ge. The changes caused by varying the bottom layer material are shown. With increase in the layer numbers the open circuit voltage increases for the total cell increases. The short circuit current density also changes with bottom layer material. Addition of layer in the multijunction solar cell can increase the overall efficiency. Different J-V characteristics curve is plotted and shown for the models considered.