Regular Article

Improved design of InGaP/GaAs//Si tandem solar cells

¹ Grupo de Investigación en Ciencias de la Orinoquia, Universidad Nacional de Colombia Sede Orinoquia, Arauca, Colombia
² Centro de Investigación y de Estudios Avanzados del IPN, Electrical Engineering Department-SEES, Ciudad de México, México

^* e-mail: amorales@solar.cinvestav.mx

Received: 19 June 2020
Received in final form: 16 January 2021
Accepted: 19 January 2021
Published online: 17 February 2021

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.