Progress and prospects for ultrathin solar cells


Ultrathin solar cells with thicknesses at least 10 times lower than conventional solar cells could have the unique potential to efficiently convert solar energy into electricity while enabling material savings, shorter deposition times and improved carrier collection in defective absorber materials. Efficient light absorption and hence high power conversion efficiency could be retained in ultrathin absorbers using light-trapping structures that enhance the optical path. Nevertheless, several technical challenges prevent the realization of a practical device. Here we review the state-of-the-art of c-Si, GaAs and Cu(In,Ga)(S,Se)2 ultrathin solar cells and compare their optical performances against theoretical light-trapping models. We then address challenges in the fabrication of ultrathin absorber layers and in nanoscale patterning of light-trapping structures and discuss strategies to ensure efficient charge collection. Finally, we propose practical architectures for ultrathin solar cells that combine photonic and electrical constraints, and identify future research directions and potential applications of ultrathin photovoltaic technologies.

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Fig. 1: State-of-the-art of ultrathin monocrystalline Si solar cells.
Fig. 2: Light-trapping performances of notable ultrathin monocrystalline Si solar cells.
Fig. 3: State-of-the-art of ultrathin GaAs solar cells.
Fig. 4: State-of-the-art of ultrathin CIGS solar cells.
Fig. 5: Transfer techniques for monocrystalline semiconductor thin-films.
Fig. 6: Techniques to fabricate nanostructures and examples of integration in solar cells.
Fig. 7: Heterostructures for passivating selective contacts.
Fig. 8: Envisioned architectures for ultrathin solar cells.


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The work by A.C. and S.C. was supported in part by the French ANR projects ULTRACIS-M under grant ANR-12-PRGE-0003, NATHISOL under grant ANR-12-PRGE-0004, NANOCELL under grant ANR-RF-2015-01, ICEMAN under grant ANR-19-CE05-0019, by the ‘Programme d’Investissement d’Avenir’ ANR-IEED-002-01 and by the H2020 project ARCIGS-M funded by the European Commission under grant 720887.

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Supplementary Data

Complete data set used in the benchmark of ultrathin solar cells (Figs. 1, 3 and 4) and refractive indices of GaAs and CIGS used in the Box and for the plot of reference models (Figs. 1, 3 and 4).

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Massiot, I., Cattoni, A. & Collin, S. Progress and prospects for ultrathin solar cells. Nat Energy 5, 959–972 (2020).

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