Improved Optics in Monolithic Perovskite/Silicon Tandem Solar Cells with a Nanocrystalline Silicon Recombination Junction

Abstract
Perovskite/silicon tandem solar cells are increasingly recognized as promi­sing candidates for next-generation photovoltaics with performance beyond the single-junction limit at potentially low production costs. Current designs for monolithic tandems rely on transparent conductive oxides as an intermediate recombination layer, which lead to optical losses and reduced shunt resistance. An improved recombination junction based on nanocrystalline silicon layers to mitigate these losses is demonstrated. When employed in monolithic perovskite/silicon heterojunction tandem cells with a planar front side, this junction is found to increase the bottom cell photocurrent by more than 1 mA cm−2. In combination with a cesium-based perovskite top cell, this leads to tandem cell power-conversion efficiencies of up to 22.7% obtained from J–V measurements and steady-state efficiencies of up to 22.0% during maximum power point tracking. Thanks to its low lateral conductivity, the nanocrystalline silicon recombination junction enables upscaling of monolithic perovskite/silicon heterojunction tandem cells, resulting in a 12.96 cm2 monolithic tandem cell with a steady-state efficiency of 18%.

Citation
Sahli F, Kamino BA, Werner J, Bräuninger M, Paviet-Salomon B, et al. (2017) Improved Optics in Monolithic Perovskite/Silicon Tandem Solar Cells with a Nanocrystalline Silicon Recombination Junction. Advanced Energy Materials: 1701609. Available: http://dx.doi.org/10.1002/aenm.201701609.

Acknowledgements
The authors acknowledge Fabien Debrot and Christophe Allebé for SHJ wet chemical processing and Vincent Paratte for Raman spectroscopy measurement. This work was funded by the Nano-Tera.ch “Synergy” project, the Swiss Federal Office of Energy under Grant SI/501072-01, and the Swiss National Science Foundation via the NRP70 “Energy Turnaround” project “PV2050.”

Publisher
Wiley

Journal
Advanced Energy Materials

DOI
10.1002/aenm.201701609

Additional Links
http://onlinelibrary.wiley.com/doi/10.1002/aenm.201701609/fullhttps://infoscience.epfl.ch/record/255299/files/Preprint.pdf

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