Effect and optimization of ZnO layer on the performance of GaInP/GaAs tandem solar cell

Two-dimentionnal Atlas SILVACO-TCAD® device simulator is used to simulate the performances of dual-junction (2J) GaInP/GaAs tandem solar cell under AM1.5G illumination spectrum. The structure of GaInP/GaAs tandem solar cell consists of the combination of two single-junctions based on GaInP top-cell and GaAs bottom-cell. The performance of GaInP/GaAs tandem solar cell is studied using ZnO intermediate layer as a transparent conducting oxide (TCO) between the bottom and top cells to connect them in serial structure. An undoped ZnO front layer is used as an anti-reflective (AR) layer in front side of GaInP top-cell to enhance the conversion efficiency. Without ZnO front layer, a conversion efficiency of 25.29% has been achieved with 0.95 μm base layer thickness of GaInP top-cell and a current-matching density for both cells was Jsc = 11.30 mA/cm2. Optimization resulted in record efficiency of 30.82% in GaInP/GaAs tandem solar cell by introducing ZnO front layer with 0.7 μm base layer thickness of GaInP top-cell with a current-matching density of 13.66 mA/cm2 and an open circuit voltage of 2.51 V. The GaInP/GaAs tandem solar cell in current study exhibit an improvement in conversion efficiency using anti-reflective ZnO front layer. This results are a promising step to fabricate an efficient III‐V multi-junctions solar cells.