Abstract
Optimizing any tandem solar cells design before making them experimentally is an important way of reducing development costs. Hence, in this work, we have used a complete analytical model that includes the important effects in the depletion regions of the III-V compound cells in order to simulate the behavior of two and four-terminal InGaP/GaAs//Si tandem solar cells for optimizing them. The design optimization procedure is described first, and then it is shown that the expected practical efficiencies at 1 sun (AM1.5 spectrum) for both two and four-terminal tandem cells can be around 40% when the appropriate thickness for each layer is used. The optimized design for both structures includes a double MgF2/ZnS anti-reflection layer (ARC). The results show that the optimum thicknesses are 130 (MgF2) and 60 nm (ZnS), respectively, while the optimum InGaP thickness is 220 nm and GaAs optimum thickness is 1800 nm for the four-terminal tandem on a HIT silicon solar cell (with total tandem efficiency around 39.8%). These results can be compared with the recent record experimental efficiency around 35.9% for this kind of solar cells. Therefore, triple junction InGaP/GaAs//Silicon tandem solar cells continue being very attractive for further development, using high efficiency HIT silicon cell as the bottom sub-cell.
Highlights
Over the last decades, photovoltaic energy has become one important contributor to the current energy production, around 1.7% of the world power supply [1]
Thin film solar cells based on CdTe, copper indium gallium selenide (CIGS) or amorphous silicon have been developed as a cheaper alternative to crystalline silicon cells [2,3,4,5,6,7]
Tandem cells, or multi-junction cells, as they are called, were originally used for spacecrafts, where materials such as gallium-arsenide (GaAs) and germanium (Ge) substrates were combined for the first time to achieve high efficiencies [8,9,10]
Summary
Photovoltaic energy has become one important contributor to the current energy production, around 1.7% of the world power supply [1]. It is shown that improved designs of two-terminal and fourterminal three-junction InGaP/GaAs//Si tandem solar cells with a double anti-reflection coating (Fig. 1) can achieve even higher efficiencies, around 39.8%, at one sun. The calculations and design results are more realistic than those typically reported without considering these space-charge effects
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
