Fabrication of Semi-Transparent Perovskite Solar Cells Suitable for 4-Terminal Silicon-Perovskite Tandem Cell Applications.
Author: Zoe Grace Bodinetz
Year: 2023
Supervisors: Halldór Guðfinnur Svavarsson, Professor Adelio Mendes, Dr. Seydali Emami
Abstract:
Since their first demonstration in 2009, a perovskite solar cells have shown rapid progress in the field of photovoltaics, reaching unprecedented efficiencies in a short space of time. Perovskite solar cells are based on the general crystal ABX3 where A is a large monovalent cation, B is a bivalent cation, and X is a halide ion. It has been shown that adjusting and engineering the ions used and their relative amounts can effectively tune the bandgap of the perovskite material within the range of ≈1.6 to above 2eV. through alteration of the crystal structure. This thesis has investigated different compositions for wide bandgap perovskites suitable for the top cell in a 4T silicon-perovskite tandem device. Alongside constraints in the bandgap of the perovskite absorber material and electrode material, this thesis aimed to fabricate a device compatible with a novel dual laser hermetic sealing procedure developed at University of Porto. This sealing procedure ensures the long-term stability of the devices, protecting them from degradation under working conditions. It has before been demonstrated on single cells, but never on a tandem device. This work was part of a wider project to construct a hermetically sealed tandem Silicon-Perovskite tandem cell. During this thesis, three different hybrid perovskite compositions were investigated, using cell fabrication, X-ray diffraction analysis and bandgap determination to assess which composition was most effective. In an opaque cell with gold electrodes, the champion composition achieved impressive efficiencies of >18%. This composition was then used to construct semi-transparent devices, whereby the electrode material was switched for Indium Tin Oxide. Buffer layer and electrode materials and thicknesses were assessed, with champion semi-transparent devices reaching efficiencies of 12.3%. The effect of the top cell filtering on the silicon cell beneath was also investigated, with theoretical tandem device efficiencies reaching over 15%.