Projected Performance of InGaAs/GaAs Quantum Dot Solar Cells: Effects of Cap and Passivation Layers

In this work, the effects of AlxGa1-xAs cap and passivation (such as SiO2, Si3N4, and HfO2) layers on the performance of InGaAs/GaAs-based quantum dot intermediate band solar cells (QDIBSCs) have been studied. The low surface recombination rate of 103 per cm3s is achieved by optimizing the composition, x =0.40 , and thickness (200 nm) of the AlxGa1-xAs cap layer. The optical reflectance is also evaluated for devices with different passivation. The solar cell with Si3N4 shows the lowest reflectance of 10.53%. The photogeneration rate has been enhanced at the quantum dot region because of the improvement of the photocurrent provides by both cap and passivation layers. There is also an increment found in the average external quantum efficiency of 39.56% as compared to that of the bared conventional QDIBSC. As a result, the solar cell, with both Al0.40Ga0.60As cap and Si3N4 passivation layers, shows the conversion efficiency of 27.8%, which is higher than that of 21.6% for conventional In0.53Ga0.47AS/GaAs-based QDIBSC. These results indicate that GaAs-based QDIBSCs with both Al0.40Ga0.60As cap and Si3N4 passivation layers are promising for next-generation photovoltaic applications.