Opto-electrical modelling of perovskite/perovskite/silicon triple-junction solar cells: Towards the practical efficiency potential

Perovskite-based triple-junction solar cells offer the potential for highly efficient and cost-effective photovoltaic energy conversion. This article aims to provide a roadmap for the optical properties of perovskite/perovskite/silicon triple-junction cells. A comprehensive optoelectrical model for the perovskite/perovskite/silicon structure is developed in Sentaurus TCAD. The optical part of the model is validated by measurements of a triple-junction solar cell. As the electrical characterization is an ongoing process, the electrical properties are assumed to be nonlimiting, which enables us to translate the optical improvement steps into efficiency potentials. A first improvement step lies in adjusting the thicknesses of the perovskite layers to achieve current matching between both perovskite subcells. Using perovskites with bandgaps optimized for planar surfaces, it would be possible to increase the photocurrent density to 13.3 mA cm-2 and the efficiency to 41.9%. It is shown that by implementing a fully textured structure and using the best available materials, a short-circuit current of 14.1 mA cm-2 and an open-circuit voltage of 3.48 V with an efficiency of 44.3% are possible assuming idealized electrical properties. This can be regarded as a practical efficiency potential for this kind of triple-junction technology.