Nanostructured front electrodes for perovskite/c-Si tandem photovoltaics

• Published in: Optics express 2020-03, Vol.28 (6), p.8878-8897
• Main Authors: Hossain, Ihteaz M, Donie, Yidenekachew J, Schmager, Raphael, Abdelkhalik, Mohamed S, Rienäcker, Michael, Wietler, Tobias F, Peibst, Robby, Karabanov, Andrei, Schwenzer, Jonas A, Moghadamzadeh, Somayeh, Lemmer, Ulrich, Richards, Bryce S, Gomard, Guillaume, Paetzold, Ulrich W
• Format: Article
• Language: English
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.382253

The rise in the power conversion efficiency (PCE) of perovskite solar cells has triggered enormous interest in perovskite-based tandem photovoltaics. One key challenge is to achieve high transmission of low energy photons into the bottom cell. Here, nanostructured front electrodes for 4-terminal perovskite/crystalline-silicon (perovskite/c-Si) tandem solar cells are developed by conformal deposition of indium tin oxide (ITO) on self-assembled polystyrene nanopillars. The nanostructured ITO is optimized for reduced reflection and increased transmission with a tradeoff in increased sheet resistance. In the optimum case, the nanostructured ITO electrodes enhance the transmittance by ∼7% (relative) compared to planar references. Perovskite/c-Si tandem devices with nanostructured ITO exhibit enhanced short-circuit current density (2.9 mA/cm absolute) and PCE (1.7% absolute) in the bottom c-Si solar cell compared to the reference. The improved light in-coupling is more pronounced for elevated angle of incidence. Energy yield enhancement up to ∼10% (relative) is achieved for perovskite/c-Si tandem architecture with the nanostructured ITO electrodes. It is also shown that these nanostructured ITO electrodes are also compatible with various other perovskite-based tandem architectures and bear the potential to improve the PCE up to 27.0%.