Tandem devices combining perovskite and silicon solar cells are promising candidates to achieve power conversion efficiencies above 30% at reasonable costs. State-of-the-art monolithic two-terminal perovskite/silicon tandem devices have so far featured silicon bottom cells that are polished on their front side to be compatible with the perovskite fabrication process. This concession leads to higher potential production costs, higher reflection losses and non-ideal light trapping. To tackle this issue, we developed a top cell deposition process that achieves the conformal growth of multiple compounds with controlled optoelectronic properties directly on the micrometre-sized pyramids of textured monocrystalline silicon. Tandem devices featuring a silicon heterojunction cell and a nanocrystalline silicon recombination junction demonstrate a certified steady-state efficiency of 25.2%. Our optical design yields a current density of 19.5 mA cm2 thanks to the silicon pyramidal texture and suggests a path for the realization of 30% monolithic perovskite/silicon tandem devices.

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  1. 1.

    Battaglia, C., Cuevas, A. & De Wolf, S. High-efficiency crystalline silicon solar cells: status and perspectives. Energy Environ. Sci. 9, 1552–1576 (2016).

  2. 2.

    Richter, A., Hermle, M. & Glunz, S. Crystalline silicon solar cells reassessment of the limiting efficiency for crystalline silicon solar cells. IEEE J. Photovolt. 3, 1184–1191 (2013).

  3. 3.

    NREL Efficiency Chart (NREL, 2017).

  4. 4.

    Yoshikawa, K. et al. Exceeding conversion efficiency of 26% by heterojunction interdigitated back contact solar cell with thin film Si technology. Sol. Energy Mater. Sol. Cells 173, 37–42 (2017).

  5. 5.

    Essig, S. et al. Raising the one-sun conversion efficiency of III–V/Si solar cells to 32.8% for two junctions and 35.9% for three junctions. Nat. Energy 2, 17144 (2017).

  6. 6.

    Werner, J., Niesen, B. & Ballif, C. Perovskite/silicon tandem solar cells: Marriage of convenience or true love story? - An overview. Adv. Mater. Interfaces 5, 1700731 (2018).

  7. 7.

    Fu, F. et al. High-efficiency inverted semi-transparent planar perovskite solar cells in substrate configuration. Nat. Energy 2, 16190 (2016).

  8. 8.

    Yang, W. S. et al. Iodide management in formamidinium-lead-halide–based perovskite layers for efficient solar cells. Science 356, 1376–1379 2017).

  9. 9.

    De Wolf, S. et al. Organometallic halide perovskites: Sharp optical absorption edge and its relation to photovoltaic performance. J. Phys. Chem. Lett. 5, 1035–1039 (2014).

  10. 10.

    Eperon, G. E. et al. Formamidinium lead trihalide: a broadly tunable perovskite for efficient planar heterojunction solar cells. Energy Environ. Sci. 7, 982–988 2014).

  11. 11.

    Grant, D. T., Catchpole, K. R., Weber, K. J. & White, T. P.. Design guidelines for perovskite/silicon 2-terminal tandem solar cells: an optical study. Opt. Express 24, A1454–A1470 2016).

  12. 12.

    Bush, K. A. et al. 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. Nat. Energy 2, 17009 (2017).

  13. 13.

    Ramírez Quiroz, C. O. et al. Balancing electrical and optical losses for efficient 4-terminal Si–perovskite solar cells with solution processed percolation electrodes. J. Mater. Chem. A 6, 3583–3592 (2018).

  14. 14.

    Werner, J. et al. Efficient near-infrared-transparent perovskite solar cells enabling direct comparison of 4-terminal and monolithic perovskite/silicon tandem cells. ACS Energy Lett. 1, 474–480 (2016).

  15. 15.

    Albrecht, S. et al. Monolithic perovskite/silicon-heterojunction tandem solar cells processed at low temperature. Energy Environ. Sci. 9, 81–88 (2016).

  16. 16.

    Taguchi, M., Terakawa, A., Maruyama, E. & Tanaka, M. Obtaining a higher V oc in HIT cells. Prog. Photovolt. Res. Appl. 13, 481–488 (2005).

  17. 17.

    Holman, Z. C., Descoeudres, A., De Wolf, S. & Ballif, C. Record infrared internal quantum efficiency in silicon heterojunction solar cells with dielectric/metal rear reflectors. IEEE J. Photovolt. 3, 1243–1249 (2013).

  18. 18.

    Burschka, J. et al. Sequential deposition as a route to high-performance perovskite-sensitized solar cells. Nature 499, 316–319 (2013).

  19. 19.

    Santbergen, R. et al. Minimizing optical losses in monolithic perovskite/c-Si tandem solar cells with a flat top cell. Opt. Express 24, A1288–A1299 2016).

  20. 20.

    Schneider, B. W. et al. Pyramidal surface textures for light trapping and antireflection in perovskite-on-silicon tandem solar cells. Opt. Express 22, A1422–A1430 (2014).

  21. 21.

    Longo, G. et al. Fully vacuum-processed wide band gap mixed-halide perovskite solar cells. ACS Energy Lett. 3, 214–219 (2018).

  22. 22.

    Ioakeimidis, A., Christodoulou, C., Lux-Steiner, M. & Fostiropoulos, K. Effect of PbI2 deposition rate on two-step PVD/CVD all-vacuum prepared perovskite. J. Solid State Chem. 244, 20–24 (2016).

  23. 23.

    Leyden, M. R., Jiang, Y. & Qi, Y. Chemical vapor deposition grown formamidinium perovskite solar modules with high steady state power and thermal stability. J. Mater. Chem. A 4, 13125–13132 (2016).

  24. 24.

    Werner, J. et al. Efficient monolithic perovskite/silicon tandem solar cell with cell area > 1 cm2. J. Phys. Chem. Lett. 7, 161–166 (2016).

  25. 25.

    Werner, J. et al. Complex refractive indices of cesium-formamidinium-based mixed halide perovskites with optical bandgaps from 1.5 to 1.8 eV. ACS Energy Lett. 3, 742–747 (2018).

  26. 26.

    Sahli, F. et al. Improved optics in monolithic perovskite/silicon tandem solar cells with a nanocrystalline silicon recombination junction. Adv. Energy Mater. 8, 1701609 (2017).

  27. 27.

    Tomasi, A. et al. Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth. Nat. Energy 2, 17062 (2017).

  28. 28.

    Wu, Y. et al. Monolithic perovskite/silicon-homojunction tandem solar cell with over 22% efficiency. Energy Environ. Sci. 10, 2472–2479 (2017).

  29. 29.

    de Wolf, S., Descoeudres, A., Holman, Z. C. & Ballif, C. High-efficiency silicon heterojunction solar cells: A review. Green 2, 7–24 (2012).

  30. 30.

    Morales-Masis, M., Martin de Nicolas, S., Holovský, J., De Wolf, S. & Ballif, C. Low-temperature high-mobility amorphous IZO for silicon heterojunction solar cells. IEEE J. Photovolt. 5, 1340–1347 (2015).

  31. 31.

    Werner, J. et al. Sputtered rear electrode with broadband transparency for perovskite solar cells. Sol. Energy Mater. Sol. Cells 141, 407–413 (2015).

  32. 32.

    De Wolf, S. & Kondo, M. Nature of doped a-Si:H/c-Si interface recombination. J. Appl. Phys. 105, 103707 (2009).

  33. 33.

    Buehlmann, P. et al. In situ silicon oxide based intermediate reflector for thin-film silicon micromorph solar cells. Appl. Phys. Lett. 91, 143505 (2007).

  34. 34.

    Unger, E. L. et al. Hysteresis and transient behavior in current–voltage measurements of hybrid-perovskite absorber solar cells. Energy Environ. Sci. 7, 3690–3698 (2014).

  35. 35.

    Eames, C. et al. Ionic transport in hybrid lead iodide perovskite solar cells. Nat. Commun. 6, 7497 (2015).

  36. 36.

    Jeangros, Q. et al. In situ TEM analysis of organic–inorganic metal-halide perovskite solar cells under electrical bias. Nano Lett. 16, 7013–7018 (2016).

  37. 37.

    Li, C. et al. Iodine migration and its effect on hysteresis in perovskite solar cells. Adv. Mater. 28, 2446–2454 (2016).

  38. 38.

    Levine, I. et al. Interface-dependent ion migration/accumulation controls hysteresis in MAPbI3 solar cells. J. Phys. Chem. C. 120, 16399–16411 (2016).

  39. 39.

    Descoeudres, A. et al. Low-temperature processes for passivation and metallization of high-efficiency crystalline silicon solar cells. Sol. Energy https://doi.org/10.1016/j.solener.2018.01.074 (2018).

  40. 40.

    Correa-Baena, J.-P. et al. Identifying and suppressing interfacial recombination to achieve high open-circuit voltage in perovskite solar cells. Energy Environ. Sci. 10, 1207–1212 (2017).

  41. 41.

    Bryant, D. et al. Light and oxygen induced degradation limits the operational stability of methylammonium lead triiodide perovskite solar cells. Energy Environ. Sci. 9, 1655–1660 (2016).

  42. 42.

    Domanski, K., Alharbi, E. A., Hagfeldt, A., Grätzel, M. & Tress, W. Systematic investigation of the impact of operation conditions on the degradation behaviour of perovskite solar cells. Nat. Energy 3, 61–67 (2018).

  43. 43.

    Nie, W. et al. Light-activated photocurrent degradation and self-healing in perovskite solar cells. Nat. Commun. 7, 11574 (2016).

  44. 44.

    Müller, C. et al. Water infiltration in methylammonium lead iodide perovskite: Fast and inconspicuous. Chem. Mater. 27, 7835–7841 (2015).

  45. 45.

    Duong, T. et al. Rubidium multication perovskite with optimized bandgap for perovskite-silicon tandem with over 26% efficiency. Adv. Energy Mater. 7, 1700228 (2017).

  46. 46.

    Kato, Y. et al. Silver iodide formation in methyl ammonium lead iodide perovskite solar cells with silver top electrodes. Adv. Mater. Interfaces 2, 2–7 (2015).

  47. 47.

    Alberti, A. et al. Similar structural dynamics for the degradation of CH3NH3PbI3 in air and in vacuum. ChemPhysChem 16, 3064–3071 (2015).

  48. 48.

    Han, Y. et al. Degradation observations of encapsulated planar CH3NH3PbI3 perovskite solar cells at high temperatures and humidity. J. Mater. Chem. A 3, 8139–8147 (2015).

  49. 49.

    Hsiao, Y.-T. & Chen, C.-H. Maximum power tracking for photovoltaic power system. In Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344) 2, 1035–1040 (IEEE, 2002).

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The authors thank F. Debrot and C. Allebé for SHJ wet-chemical processing, J. Geissbühler for help regarding the Arduino microcontroller and circuit design, G. Charitat for the bottom cell deposition and A. Walter, S.-J. Moon, T. C.-J. Yang, P. Fiala and F. Fu for help regarding perovskite top cell processes and fruitful discussions. This work was funded by the Nano-Tera.ch Synergy project, the Swiss Federal Office of Energy under grant SI/501072-01, the Swiss National Science Foundation via the Sinergia Episode (CRSII5_171000) and NRP70 Energy Turnaround PV2050 (407040) projects and the European Union’s Horizon 2020 research and innovation program under grant agreement no. 653296 (CHEOPS).

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  1. These authors contributed equally: Florent Sahli and Jérémie Werner.


  1. Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT) Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Neuchâtel, Switzerland

    • Florent Sahli
    • , Jérémie Werner
    • , Matthias Bräuninger
    • , Raphaël Monnard
    • , Mathieu Boccard
    • , Quentin Jeangros
    •  & Christophe Ballif
  2. CSEM, PV-Center, Neuchâtel, Switzerland

    • Brett A. Kamino
    • , Bertrand Paviet-Salomon
    • , Loris Barraud
    • , Laura Ding
    • , Juan J. Diaz Leon
    • , Davide Sacchetto
    • , Gianluca Cattaneo
    • , Matthieu Despeisse
    • , Sylvain Nicolay
    • , Bjoern Niesen
    •  & Christophe Ballif


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F.S. and J.W. contributed equally to this work. F.S and J.W designed the experiments and carried out the device fabrication. B.A.K. and M.Br. contributed to the development of the perovskite top cell. R.M., B.P.-S., L.B., M.Bo. and M.D. developed and fabricated the silicon heterojunction bottom cells. D.S., L.D. and J.J.D.L developed the ALD buffer layer. G.C. and B.N. carried out the encapsulation for stability tests. Q.J. performed the FIB and TEM characterization and, with J.W., the SEM analysis. M.Br. recorded the AFM data. F.S., J.W. and Q.J. carried out data analysis and prepared the figures. J.W. carried out the degradation stability tests and analysed the data. Q.J., B.N., M.Bo., M.D., S.N. and C.B. supervised different parts of the work. F.S. and Q.J. wrote the paper, and all authors commented on the manuscript.

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Correspondence to Florent Sahli or Quentin Jeangros.

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