Monolithic 2-Terminal Perovskite Silicon Tandem Solar Cells

Patricia S. C. Schulze^a, Özde Ş. Kabaklı^a, Minasadat Heydarian^a^,^b, Oussama Er-Raji^a^,^b, Maryamsadat Heydarian^a, Raphael Efinger^a, Oliver Schultz-Wittmann^a, Christoph Messmer^a^,^b, Alexander J. Bett^a, Oliver Fischer^a^,^b, Leonard Tutsch^a, Denis Erath^a, Sebastian Pingel^a, Thibaud Hatt^a, Martin Bivour^a, Jan Christoph Goldschmidt^a^,^c, Martin Hermle^a, Stefan W. Glunz^a^,^b

^aFraunhofer Institute for Solar Energy Systems ISE, 79110 Freiburg, Germany

^bUniversity of Freiburg, Germany, 79110 Freiburg, Germany

^cUniversity of Marburg, Germany, 35037 Marburg, Germany

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)

València, Spain, 2022 May 19th - 25th

Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson

Oral, Patricia S. C. Schulze, presentation 183
DOI: https://doi.org/10.29363/nanoge.hopv.2022.183
Publication date: 20th April 2022

To enable terawatt-scale photovoltaics, resource and cost efficiency are mandatory. Perovskite silicon tandem solar cells can achieve both goals by exceeding the efficiency limit of 29.4% of single junction silicon solar cells [1], with only little additional production costs [2]. We aim for monolithic 2-terminal tandem devices to facilitate module integration and to avoid parasitic absorption in laterally conductive layers.

Starting from a p-i-n perovskite top solar cell with a 1.68 eV absorber on p-type heterojunction silicon bottom solar cells with a pyramidal rear side texture and a planar front [3], we elaborate optimization steps to maximize the photocurrents in the sub-cells and achieve current matching. Supported by optical simulation using transfer matrix formalism [4,5], main process adaptions are addressed, e.g. development of a more transparent front contact layer and fine-tuning the perovskite band gap. Spectral metric analysis [6] – comprising a systematic variation of the illumination spectrum, while keeping the overall irradiance constant – is applied to access the individual sub-cell´s current generation and confirm current matching. A certified current density of 19.6 mA/cm² is achieved for optimized tandem devices with planar front. For further current increase and higher energy yield [7], fully textured tandem devices are needed. For this purpose, we investigate the dry/wet hybrid (evaporation and wet processing) route to allow perovskite deposition with tuneable band gap on µm-sized silicon texture.

Concerning the tandem´s voltage, we investigate different charge transport materials and interface passivation. Electrical simulation of our full tandem stack in Sentaurus TCAD gives insight into the tandem´s band diagram and charge carrier extraction and serves as basis for further device optimization.

Regarding metallization and up-scaling, low-temperature silver paste screen printing is investigated for front metallization of the tandem device. Considering high costs of silver, electroplated copper contacts are considered as an alternative and demonstrated on semi‑transparent perovskite solar cells as a proof-of-concept [8].

References:

[1] A. Richter, M. Hermle, S. W. Glunz, “Reassessment of the Limiting Efficiency for Crystalline Silicon Solar Cells”, IEEE Journal of Photovoltaics, vol. 3, no. 4, pp. 1184–1191, 2013.

[2] L. A. Zafoschnig, S. Nold, and J. C. Goldschmidt, “The Race for Lowest Costs of Electricity Production: Techno-Economic Analysis of Silicon, Perovskite and Tandem Solar Cells,” IEEE Journal of Photovoltaics, vol. 10, no. 6, pp. 1632–1641, 2020.

[3] P. S. C. Schulze et al., “25.1% High‐Efficient Monolithic Perovskite Silicon Tandem Solar Cell with a High Band Gap Perovskite Absorber,” Solar RRL, vol. 4, no. 7, p. 2000152, 2020.

[4] C. Messmer et al., „ The race for the best silicon bottom cell: Efficiency and cost evaluation of perovskite–silicon tandem solar cells”, Progress in Photovoltaics: Research and Applications, vol. 29, no. 7, pp. 744-759, 2020.

[5] C. Messmer et al. “Optimized front TCO and metal grid electrode for module-integrated perovskite–silicon tandem solar cells”, Progress in Photovoltaics: Research and Applications, 2021.

[6] M. Meusel et al., “Spectral mismatch correction and spectrometric characterization of monolithic III–V multi-junction solar cells”, Progress in Photovoltaics: Research and Applications, vol. 10, no. 4, pp. 243–255, 2002.

[7] Tucher et al., “Energy yield analysis of textured perovskite silicon tandem solar cells and modules”, Optics Express, vol. 27, no. 20, pp. A1419-A1430, 2019.

[8] T. Hatt et al., “Electroplated Copper Metal Contacts on Perovskite Solar Cells”, Solar RRL, vol. 5, no.9, p. 2100381, 2021.

Acknowledgements:

This work was partially supported by the Fraunhofer Lighthouse Project MaNiTU and the German Federal Ministry for Economic Affairs and Energy (BMWi) under contract number 03EE1086A (prEsto) and 03EE1087A (KATANA).

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