Contribution of the Doping of the Lower Window Layer to Improve the Performances of the Tandem Solar Cell

Each layer of the tandem solar cell, its doping or its thickness, plays a primary task in improving the conversion efficiency. The optimization of the doping of the window layer of the lower solar cell of the tandem cell contributes to the reduction of the cost of the manufacture of its cells. The objective of this work is to show the role of doping the lower window layer on the performances of tandem CS in InGaP / GaAs with a tunnel heterojunction. For this a simulation is carried out using the Atlas-Silvaco simulator. It is specially designed for 2D and 3D modeling of components based on the physics of semiconductors, including electrical, optical and thermal properties The adapted structure is essentially composed of an upper cell in InGaP and a lower cell in GaAs. Between the two upper and lower cells, there is a heterojunction tunnel) P ++ N ++. The structure studied is composed of a thin window layer heavily doped with the materialIn0.629Al0.159Ga0.371P0.841 .Our simulation showed that, for an illumination of AM 1.5 and at room temperature, the parameters, such as the short-circuit current and the conversion efficiency, improve with the doping of the upper window layer.The best conversion efficiency is 24.2343% for a doping of 8x1018 cm-3.