Stannowski, B.; Mazzarella, L.; Lin, Y.-H.; Kirner, S.; Morales-Vilches, A.B.; Korte, L.; Albrecht, S.; Crossland, E.; Case, C.; Snaith, H.; Schlatmann, R.: Nanocrystalline silicon oxide interlayer in monolithic perovskite/silicon heterojunction tandem solar cells with total current density >39 mA/cm². In: 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC). IEEE, 2018. - ISBN 978-1-5386-8530-3, p. 2627-2630
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Silicon heterojunction solar cells are implemented as bottom cells in monolithic perovskite/silicon tandem solar cells. Commonly they are processed with a smooth front side to facilitate wet processing of the lead-halide perovskite cell on top. The inherent drawback of this design, namely, enhanced reflection of the cell, can be significantly reduced by replacing the amorphous or nanocrystalline silicon front side n layer of the silicon cell by a nanocrystalline silicon oxide n layer. It is deposited with the same commonly used plasma-enhanced chemical vapor deposition and can be tuned to feature opto-electrical properties for enhanced light coupling into the Si bottom cell, namely, low parasitic absorption and an intermediate refractive index of ~2.6. We demonstrate that a 80 - 100 nm thick layer results in 0.9 mA/cm 2 current gain in the bottom cell yielding tandem cells with a top cell + bottom cell total current above 39 mA/cm 2 . These first nc-SiO x :H-coupled tandem cells reach an efficiency >23.5 %.