A monolithic nanostructured-perovskite/silicon tandem solar cell: feasibility of light management through geometry and materials selection

Mahmoud H Elshorbagy,Ricardo Vergaz,Eduardo López-Fraguas,Braulio García-Cámara,Fateh A Chaudhry,José Manuel Sánchez-Pena

doi:10.1038/s41598-020-58978-5

Mahmoud H Elshorbagy, Ricardo Vergaz + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-58978-5

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Abstract

The use of several layers of different materials, taking advantage of their complementary bandgap energies, improves the absorption in multi-junction solar cells. Unfortunately, the inherent efficiency increment of this strategy has a limitation: each interface introduces optical losses. In this paper, we study the effects of materials and geometry in the optical performance of a nanostructured hybrid perovskite – silicon tandem solar cell. Our proposed design increases the performance of both subcells by managing light towards the active layer, as well as by minimizing reflections losses in the interfaces. We sweep both refractive index and thickness of the transport layers and the dielectric spacer composing the metasurface, obtaining a range of these parameters for the proper operation of the device. Using these values, we obtain a reduction in the optical losses, in particular they are more than a 33% lower than those of a planar cell, mainly due to a reduction of the reflectivity in the device. This approach leads to an enhancement in the optical response, widens the possibilities for the manufacturers to use different materials, and allows wide geometrical tolerances.

Highlights

The use of several layers of different materials, taking advantage of their complementary bandgap energies, improves the absorption in multi-junction solar cells
We focus the analysis on the hole transport layer (HTL), electron transport layer (ETL) and the dielectric spacer (DS) to find out the values ranges of geometrical parameters and refractive indices that allow a minimization of these losses
We present a survey on the possible HTL, ETL and DS materials, as well as their thicknesses, to reduce the optical losses in the solar cell

Summary

Introduction

The use of several layers of different materials, taking advantage of their complementary bandgap energies, improves the absorption in multi-junction solar cells. Our proposed design increases the performance of both subcells by managing light towards the active layer, as well as by minimizing reflections losses in the interfaces We sweep both refractive index and thickness of the transport layers and the dielectric spacer composing the metasurface, obtaining a range of these parameters for the proper operation of the device. The recent years have seen a boost in the research and development of perovskite solar cells, due to its remarkable increase in efficiency, ease of fabrication and performance possibilities[1,2] In their tandem configuration with crystalline Silicon[3,4], the way to stack all the layers is the key point. The goal for achieving the best design of a two-terminal tandem solar cell is to reduce the optical losses as well as to improve the charge extraction, while maintaining a match between the currents photogenerated in each subcell. We offer a high geometrical tolerance that allows the optimum performance of the cell

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