Progress and prospects for ultrathin solar cells

Abstract

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.

References

  1. 1.

    Renewable power generation by technology in the Sustainable Development Scenario, 2000-2030. IEA https://www.iea.org/data-and-statistics/charts/renewable-power-generation-by-technology-in-the-sustainable-development-scenario-2000-2030 (2020).

  2. 2.

    Shockley, W. & Queisser, H. J. Detailed balance limit of efficiency of p-n junction solar cells. J. Appl. Phys. 32, 510–519 (1961).

    Article  Google Scholar 

  3. 3.

    Kayes, B. M. et al. 27.6% conversion efficiency, a new record for single-junction solar cells under 1 sun illumination. In Proc. 37th IEEE Photovoltaic Specialists Conference 4–8 (2011).

  4. 4.

    Green, M. A. et al. Solar cell efficiency tables (version 53). Prog. Photovolt. 27, 3–12 (2019).

    Article  Google Scholar 

  5. 5.

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

    Article  Google Scholar 

  6. 6.

    Yoshikawa, K. et al. Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%.Nat. Energy 2, 17032 (2017). High-efficiency heterojunction solar cells with e- /h+ selective contacts.

    Article  Google Scholar 

  7. 7.

    Nakamura, M. et al. Cd-Free Cu(In, Ga)(Se, S)2 thin-film solar cell with record efficiency of 23.35%. IEEE J. Photovolt. 9, 1863–1867 (2019).

    Article  Google Scholar 

  8. 8.

    Andreani, L. C., Bozzola, A., Kowalczewski, P., Liscidini, M. & Redorici, L. Silicon solar cells: toward the efficiency limits. Adv. Phys. X 4, 1548305 (2019).

    Google Scholar 

  9. 9.

    Miller, O. D., Yablonovitch, E. & Kurtz, S. R. Strong internal and external luminescence as solar cells approach the Shockley–Queisser limit. IEEE J. Photovolt. 2, 303–311 (2012).

    Article  Google Scholar 

  10. 10.

    Sai, H. et al. Potential of very thin and high-efficiency silicon heterojunction solar cells. Prog. Photovolt. 27, 1061–1070 (2019).

    Article  Google Scholar 

  11. 11.

    Liu, Z. et al. Revisiting thin silicon for photovoltaics: a technoeconomic perspective. Energy Environ. Sci. 13, 12–23 (2020).

    Article  Google Scholar 

  12. 12.

    Bhattacharya, S., Baydoun, I., Lin, M. & John, S. Towards 30% power conversion efficiency in thin-silicon photonic-crystal solar cells. Phys. Rev. Appl. 11, 014005 (2019).

    Article  Google Scholar 

  13. 13.

    Petermann, J. H. et al. 19%-efficient and 43 µm-thick crystalline Si solar cell from layer transfer using porous silicon. Prog. Photovolt. 20, 1–5 (2012). CVD epitaxial growth of c-Si layers (t = 43 µm) on recrystallized porous silicon and transfer.

    Article  Google Scholar 

  14. 14.

    Haug, F.-J. & Ballif, C. Light management in thin film silicon solar cells. Energy Environ. Sci. 8, 824–837 (2015).

    Article  Google Scholar 

  15. 15.

    Erwin, W. R., Zarick, H. F., Talbert, E. M. & Bardhan, R. Light trapping in mesoporous solar cells with plasmonic nanostructures. Energy Environ. Sci. 9, 1577–1601 (2016).

    Article  Google Scholar 

  16. 16.

    Liu, J., Yao, M. & Shen, L. Third generation photovoltaic cells based on photonic crystals. J. Mater. Chem. C 7, 3121–3145 (2019).

    Article  Google Scholar 

  17. 17.

    Jena, A. K., Kulkarni, A. & Miyasaka, T. Halide perovskite photovoltaics: background, status, and future prospects. Chem. Rev. 119, 3036–3103 (2019).

    Article  Google Scholar 

  18. 18.

    Powalla, M. et al. Thin-film solar cells exceeding 22 % solar cell efficiency: an overview on CdTe-, Cu(In, Ga)Se2-, and perovskite-based materials. Appl. Phys. Rev. 5, 041602 (2018).

    Article  Google Scholar 

  19. 19.

    Liu, X. et al. The current status and future prospects of kesterite solar cells: a brief review. Prog. Photovolt. 24, 879–898 (2016).

    Article  Google Scholar 

  20. 20.

    Wang, A., Zhao, J., Wenham, S. R. & Green, M. A. 21.5% Efficient thin silicon solar cell. Prog. Photovolt. 4, 55–58 (1996).

    Article  Google Scholar 

  21. 21.

    Branham, M. S. et al. 15.7% Efficient 10-μm-thick crystalline silicon solar cells using periodic nanostructures. Adv. Mater. 27, 2182–2188 (2015). This paper reports the first ultrathin silicon solar cell (t = 10 μm) with a short-circuit current exceeding significantly single-pass absorption and leading to an efficiency η = 15.7%.

    Article  Google Scholar 

  22. 22.

    Gaucher, A. et al. Ultrathin epitaxial silicon solar cells with inverted nanopyramid arrays for efficient light trapping. Nano Lett. 16, 5358–5364 (2016).

    Article  Google Scholar 

  23. 23.

    Depauw, V. et al. Sunlight-thin nanophotonic monocrystalline silicon solar cells. Nano Futures 1, 021001 (2017).

    Article  Google Scholar 

  24. 24.

    Zhou, S. et al. Wafer-scale integration of inverted nanopyramid arrays for advanced light trapping in crystalline silicon thin film solar cells. Nanoscale Res. Lett. 11, 194 (2016).

    Article  Google Scholar 

  25. 25.

    Kuang, P. et al. Achieving an accurate surface profile of a photonic crystal for near-unity solar absorption in a super thin-film architecture. ACS Nano 10, 6116–6124 (2016).

    Article  Google Scholar 

  26. 26.

    Chong, T. K., Wilson, J., Mokkapati, S. & Catchpole, K. R. Optimal wavelength scale diffraction gratings for light trapping in solar cells. J. Opt. 14, 024012 (2012).

    Article  Google Scholar 

  27. 27.

    Wang, K. X., Yu, Z., Liu, V., Cui, Y. & Fan, S. Absorption enhancement in ultrathin crystalline silicon solar cells with antireflection and light-trapping nanocone gratings. Nano Lett. 12, 1616–1619 (2012).

    Article  Google Scholar 

  28. 28.

    Eyderman, S. et al. Light-trapping optimization in wet-etched silicon photonic crystal solar cells. J. Appl. Phys. 118, 023103 (2015).

    Article  Google Scholar 

  29. 29.

    Eyderman, S., John, S. & Deinega, A. Solar light trapping in slanted conical-pore photonic crystals: beyond statistical ray trapping. J. Appl. Phys. 113, 154315 (2013).

    Article  Google Scholar 

  30. 30.

    Martins, E. R. et al. Deterministic quasi-random nanostructures for photon control. Nat. Commun. 4, 2665 (2013).

    Article  Google Scholar 

  31. 31.

    Meng, X. et al. Combined front and back diffraction gratings for broadband light trapping in thin film solar cells. Opt. Express 20, A560–A571 (2012).

    Article  Google Scholar 

  32. 32.

    Shi, Y., Wang, X., Liu, W., Yang, T. & Yang, F. Light-absorption enhancement in thin-film silicon solar cells with front grating and rear-located nanoparticle grating. Phys. Status Solidi. 212, 312–316 (2014).

    Article  Google Scholar 

  33. 33.

    Haug, F.-J., Söderström, T., Cubero, O., Terrazzoni-Daudrix, V. & Ballif, C. Influence of the ZnO buffer on the guided mode structure in Si/ZnO/Ag multilayers. J. Appl. Phys. 106, 044502 (2009).

    Article  Google Scholar 

  34. 34.

    Lee, H.-S. et al. Enhanced efficiency of crystalline Si solar cells based on kerfless-thin wafers with nanohole arrays. Sci. Rep. 8, 3504 (2018).

    Article  Google Scholar 

  35. 35.

    Ingenito, A., Isabella, O. & Zeman, M. Experimental demonstration of 4n2 classical absorption limit in nanotextured ultrathin solar cells with dielectric omnidirectional back reflector. ACS Photonics 1, 270–278 (2014).

    Article  Google Scholar 

  36. 36.

    Zeng, L. et al. Demonstration of enhanced absorption in thin film Si solar cells with textured photonic crystal back reflector. Appl. Phys. Lett. 93, 221105 (2008).

    Article  Google Scholar 

  37. 37.

    Green, M. A. & Ho-Baillie, A. W. Y. Pushing to the limit: radiative efficiencies of recent mainstream and emerging solar cells. ACS Energy Lett. 4, 1639–1644 (2019).

    Article  Google Scholar 

  38. 38.

    Nakayama, K., Tanabe, K. & Atwater, H. A. Plasmonic nanoparticle enhanced light absorption in GaAs solar cells. Appl. Phys. Lett. 93, 121904 (2008).

    Article  Google Scholar 

  39. 39.

    Liu, W. et al. Surface plasmon enhanced GaAs thin film solar cells. Sol. Energy Mater. Sol. Cells 95, 693–698 (2011).

    Article  Google Scholar 

  40. 40.

    Yang, W. et al. Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer. J. Appl. Phys. 115, 203105 (2014).

    Article  Google Scholar 

  41. 41.

    Vandamme, N. et al. Ultrathin GaAs solar cells with a silver back mirror. IEEE J. Photovolt. 5, 565–570 (2015).

    Article  Google Scholar 

  42. 42.

    van Eerden, M. et al. A facile light-trapping approach for ultrathin GaAs solar cells using wet chemical etching. Prog. Photovolt. 28, 200–209 (2020).

    Article  Google Scholar 

  43. 43.

    Grandidier, J., Callahan, D., Munday, J. & Atwater, H. A. Gallium arsenide solar cell absorption enhancement using whispering gallery modes of dielectric nanospheres. IEEE J. Photovolt. 2, 123–128 (2012).

    Article  Google Scholar 

  44. 44.

    Lee, S.-M. et al. High performance ultrathin GaAs solar cells enabled with heterogeneously integrated dielectric periodic nanostructures. ACS Nano 9, 10356–10365 (2015).

    Article  Google Scholar 

  45. 45.

    Chen, H.-L. et al. A 19.9%-efficient ultrathin GaAs solar cell with a silver nanostructured back mirror. Nat. Ener. 4, 761–767 (2019). This paper reports the fabrication of an ultrathin GaAs solar cell (t = 205 nm) with a nanostructured back mirror and a conversion efficiency close to 20%.

    Article  Google Scholar 

  46. 46.

    Massiot, I. et al. Metal nanogrid for broadband multiresonant light-harvesting in ultrathin GaAs layers. ACS Photonics 1, 878–884 (2014).

    Article  Google Scholar 

  47. 47.

    Eyderman, S., Deinega, A. & John, S. Near perfect solar absorption in ultra-thin-film GaAs photonic crystals. J. Mater. Chem. A 2, 761–769 (2014).

    Article  Google Scholar 

  48. 48.

    Eyderman, S. & John, S. Light-trapping and recycling for extraordinary power conversion in ultra-thin gallium-arsenide solar cells. Sci. Rep. 6, 28303 (2016).

    Article  Google Scholar 

  49. 49.

    Aberg, I. et al. A GaAs nanowire array solar cell with 15.3% efficiency at 1 sun. IEEE J. Photovolt. 6, 185–190 (2016).

    Article  Google Scholar 

  50. 50.

    Horowitz, K. A. W., Fu, R. & Woodhouse, M. An analysis of glass-glass CIGS manufacturing costs. Sol. Energy Mater. Sol. Cells 154, 1–10 (2016).

    Article  Google Scholar 

  51. 51.

    Shafarman, W. N. et al. Effect of reduced deposition temperature, time, and thickness on Cu(InGa)Se2 films and devices. In Proc. 26th IEEE Photovoltaic Specialists Conference 331–334 (IEEE, 1997).

  52. 52.

    Lundberg, O., Bodegard, M., Malmström, J. & Stolt, L. Influence of the Cu(In, Ga)Se2 thickness and Ga grading on solar cell performance. Prog. Photovolt. 11, 77–88 (2003).

    Article  Google Scholar 

  53. 53.

    Jehl, Z. et al. Thinning of CIGS solar cells: Part II: cell characterizations. Thin Solid Films 519, 7212–7215 (2011).

    Article  Google Scholar 

  54. 54.

    Han, A. et al. Structure, morphology and properties of thinned Cu(In, Ga)Se2 films and solar cells. Semicond. Sci. Technol. 27, 035022 (2012).

    Article  Google Scholar 

  55. 55.

    Reinhard, P. et al. Flexible Cu(In, Ga)Se2 solar cells with reduced absorber thickness. Prog. Photovolt. 23, 281–289 (2013).

    Article  Google Scholar 

  56. 56.

    Pettersson, J., Törndahl, T., Platzer-Björkman, C., Hultqvist, A. & Edoff, M. The influence of absorber thickness on Cu(In, Ga)Se2 solar cells with different buffer layers. IEEE J. Photovolt. 3, 1376–1382 (2013).

    Article  Google Scholar 

  57. 57.

    Leonard, E. et al. Cu(In, Ga)Se2 absorber thinning and the homo-interface model: Influence of Mo back contact and 3-stage process on device characteristics. J. Appl. Phys. 116, 074512 (2014).

    Article  Google Scholar 

  58. 58.

    Jarzembowski, E. et al. Optical and electrical characterization of Cu(In, Ga)Se2 thin film solar cells with varied absorber layer thickness. Thin Solid Films 576, 75–80 (2015).

    Article  Google Scholar 

  59. 59.

    Yin, G., Brackmann, V., Hoffmann, V. & Schmid, M. Enhanced performance of ultra-thin Cu(In, Ga)Se2 solar cells deposited at low process temperature. Sol. Energy Mater. Sol. Cells 132, 142–147 (2015).

    Article  Google Scholar 

  60. 60.

    Vermang, B. et al. Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In, Ga)Se2 solar cells. Prog. Photovolt. 22, 1023–1029 (2014). This work demonstrates an ultrathin CIGS solar cell (t = 385 nm) with a passivated back surface and nanosized point contacts (η = 13.5%).

    Article  Google Scholar 

  61. 61.

    Vermang, B. et al. Introduction of Si PERC rear contacting design to boost efficiency of Cu(In, Ga)Se2 solar cells. IEEE J. Photovolt. 4, 1644–1649 (2014).

    Article  Google Scholar 

  62. 62.

    van Lare, C., Yin, G., Polman, A. & Schmid, M. Light coupling and trapping in ultrathin Cu(In, Ga)Se2 solar cells using dielectric scattering patterns. ACS Nano 9, 9603–9613 (2015).

    Article  Google Scholar 

  63. 63.

    Yin, G., Manley, P. & Schmid, M. Light absorption enhancement for ultra-thin Cu(In1-xGax)Se2 solar cells using closely packed 2-D SiO2 nanosphere arrays. Sol. Energy Mater. Sol. Cells 153, 124–130 (2016).

    Article  Google Scholar 

  64. 64.

    Jarzembowski, E., Fuhrmann, B., Leipner, H., Fränzel, W. & Scheer, R. Ultrathin Cu(In, Ga)Se2 solar cells with point-like back contact in experiment and simulation. Thin Solid Films 633, 61–65 (2016).

    Article  Google Scholar 

  65. 65.

    Malmström, J., Schleussner, S. & Stolt, L. Enhanced back reflectance and quantum efficiency in Cu(In, Ga)Se2 thin film solar cells with a ZrN back reflector. Appl. Phys. Lett. 85, 2634–2636 (2004).

    Article  Google Scholar 

  66. 66.

    Ohm, W. et al. Bifacial Cu(In, Ga)Se2 solar cells with submicron absorber thickness: back-contact passivation and light management. In Proc. 42nd IEEE Photovoltaic Specialists Conference. 1–5 (IEEE, 2015).

  67. 67.

    Mollica, F. et al. Light absorption enhancement in ultra-thin Cu(In, Ga)Se2 solar cells by substituting the back-contact with a transparent conducting oxide based reflector. Thin Solid Films 633, 202–207 (2016).

    Article  Google Scholar 

  68. 68.

    Gouillart, L. et al. Development of reflective back contacts for high-efficiency ultrathin Cu(In, Ga)Se2 solar cells. Thin Solid Films 672, 1–6 (2019).

    Article  Google Scholar 

  69. 69.

    Jehl, Z. et al. Towards ultrathin copper indium gallium diselenide solar cells: proof of concept study by chemical etching and gold back contact engineering. Prog. Photovolt. 20, 582–587 (2012).

    Article  Google Scholar 

  70. 70.

    Larsen, J. K., Simchi, H., Xin, P., Kim, K. & Shafarman, W. N. Backwall superstrate configuration for ultrathin Cu(In, Ga)Se2 solar cells. Appl. Phys. Lett. 104, 033901 (2014).

    Article  Google Scholar 

  71. 71.

    Dahan, N. et al. Optical approaches to improve the photocurrent generation in Cu(In, Ga)Se2 solar cells with absorber thicknesses down to 0.5 µm. J. Appl. Phys. 112, 094902 (2012).

    Article  Google Scholar 

  72. 72.

    Onwudinanti, C. et al. Advanced light management based on periodic textures for Cu(In, Ga)Se2 thin-film solar cells. Opt. Express 24, A693–A707 (2016).

    Article  Google Scholar 

  73. 73.

    Goffard, J. et al. Light trapping in ultrathin CIGS solar cells with nanostructured back mirrors. IEEE J. Photovolt. 7, 1433–1441 (2017).

    Article  Google Scholar 

  74. 74.

    Bedell, S. W. et al. Kerf-less removal of Si, Ge, and III–V layers by controlled spalling to enable low-cost PV technologies. IEEE J. Photovolt. 2, 141–147 (2012).

    Article  Google Scholar 

  75. 75.

    Saha, S. et al. Single heterojunction solar cells on exfoliated flexible ~25µm thick mono-crystalline silicon substrates. Appl. Phys. Lett. 102, 163904 (2013). Ultrathin silicon solar cell (t = 25 µm) fabricated by exfoliation, a kerf-less process.

    Article  Google Scholar 

  76. 76.

    Crouse, D. et al. Increased fracture depth range in controlled spalling of (100)-oriented germanium via electroplating. Thin Solid Films 649, 154–159 (2018).

    Article  Google Scholar 

  77. 77.

    Sweet, C. A. et al. Controlled exfoliation of (100) GaAs-based devices by spalling fracture. Appl. Phys. Lett. 108, 011906 (2016).

    Article  Google Scholar 

  78. 78.

    Bruel, M. Process for the production of thin semiconductor material films. US patent 5374564 (1994).

  79. 79.

    Mizushima, I., Sato, T., Taniguchi, S. & Tsunashima, Y. Empty-space-in-silicon technique for fabricating a silicon-on-nothing structure. Appl. Phys. Lett. 77, 3290–3292 (2000).

    Article  Google Scholar 

  80. 80.

    Kapur, P. et al. A manufacturable, non-plated, non-Ag metallization based 20.44 % efficient, 243 cm2 area, back contacted solar cell on 40 µm thick mono-crystalline silicon. In Proc. 28th European Photovoltaic Solar Energy Conference and Exhibition 2228–2231 (2013).

  81. 81.

    Wang, L. et al. Development of a 16.8% efficient 18-μm silicon solar cell on steel. IEEE J. Photovolt. 4, 1397 (2014).

    Article  Google Scholar 

  82. 82.

    Cariou, R. et al. Ultra-thin PECVD epitaxial Si solar cells on glass via low temperature transfer process. Prog. Photovolt. 24, 1075–1084 (2016).

    Article  Google Scholar 

  83. 83.

    Branz, H. M. et al. Hot-wire chemical vapor deposition of epitaxial film crystal silicon for photovoltaics. Thin Solid Films 519, 4545–4550 (2011).

    Article  Google Scholar 

  84. 84.

    Brendel, R. et al. Monocrystalline Si waffles for thin solar cells fabricated by the novel-perforated silicon process. Appl. Phys. A 67, 151 (1998).

    Article  Google Scholar 

  85. 85.

    Sakaguchi, K. et al. Current progress in epitaxial layer transfer. IEICE Trans. Electron. 378, E80-C (1997).

    Google Scholar 

  86. 86.

    Tayanaka, H., Yamauchi, K. & Matsuhita, T. Thin-film crystalline silicon solar cells obtained by separation of a porous silicon sacrificial layer. In Proc. 2nd World Conference on Photovoltaic Energy Conversion 1272 (1998).

  87. 87.

    Moslehi M. M. et al. World-record 20.6% efficiency 156 mm x 156 mm full-square solar cells using low-cost kerfless ultrathin epitaxial silicon & porous silicon lift-off technology for industry-leading high-performance smart PV modules. In Proc. The PV Asia Pacific Conference (2012).

  88. 88.

    Stern, F. & Woodall, J. M. Photon recycling in semiconductor lasers. J. Appl. Phys. 45, 3904 (1974).

    Article  Google Scholar 

  89. 89.

    Konagai, M., Sugimoto, M. & Takahashi, K. High efficiency GaAs thin film solar cells by peeled film technology. J. Cryst. Growth 45, 277–280 (1978).

    Article  Google Scholar 

  90. 90.

    Park, S. et al. Germanium-on-nothing for epitaxial liftoff of GaAs solar cells. Joule 3, 1782–1793 (2019).

    Article  Google Scholar 

  91. 91.

    McClelland, R. W., Bolzer, C. O. & Fan, J. C. C. A technique for producing epitaxial films on reuseable substrates. Appl. Phys. Lett. 37, 560 (1980).

    Article  Google Scholar 

  92. 92.

    Bozler, C. O., McClelland, R. W. & Fan, J. C. C. Ultrathin, high-efficiency solar cells made from GaAs films prepared by the CLEFT Process. IEEE Electron Device Lett. 2, 203 (1981).

    Article  Google Scholar 

  93. 93.

    Kim, Y. et al. Remote epitaxy through graphene enables two-dimensional material-based layer transfer. Nature 544, 340–343 (2017). Epitaxial growth of III–V through graphene for easy layer transfer and substrate reuse.

    Article  Google Scholar 

  94. 94.

    Bae, S. H. et al. Graphene-assisted spontaneous relaxation towards dislocation-free heteroepitaxy. Nat. Nanotechnol. 15, 272–276 (2020).

    Article  Google Scholar 

  95. 95.

    Wolf, A. J. et al. Origination of nano- and microstructures on large areas by interference lithography. Microelectron. Eng. 98, 293–296 (2012).

    Article  Google Scholar 

  96. 96.

    Solak, H., Dais, C. & Clube, F. Displacement Talbot lithography: a new method for high-resolution patterning of large areas. Opt. Express 19, 10686 (2011).

    Article  Google Scholar 

  97. 97.

    Wang, L. et al. Sub-wavelength printing in the deep ultra-violet region using Displacement Talbot Lithography. Microelectron. Eng. 161, 104–108 (2016).

    Article  Google Scholar 

  98. 98.

    Eisenlohr, J. et al. Rear side sphere gratings for improved light trapping in crystalline silicon single junction and silicon-based tandem solar cells. Sol. Energy Mater. Sol. Cells 142, 60–65 (2015).

    Article  Google Scholar 

  99. 99.

    Gao, P. et al. Large-area nanosphere self-assembly by a micro-propulsive injection method for high throughput periodic surface nanotexturing. Nano Lett. 15, 4591–4598 (2015).

    Article  Google Scholar 

  100. 100.

    Massiot, I. et al. Highly conformal fabrication of nanopatterns on non-planar surfaces. Nanoscale 8, 11461 (2016).

    Article  Google Scholar 

  101. 101.

    Trompoukis, C. et al. Disordered nanostructures by hole-mask colloidal lithography for advanced light-trapping in silicon solar cells. Opt. Express 24, A191–201 (2016).

    Article  Google Scholar 

  102. 102.

    El Daif, O. et al. Front side plasmonic effect on thin silicon epitaxial solar cells. Sol. Energy Mater. Sol. Cells 104, 58–63 (2012).

    Article  Google Scholar 

  103. 103.

    Cariou, R. et al. III-V-on-silicon solar cells reaching 33 % photoconversion efficiency in two-terminal configuration. Nat. Ener. 3, 326–333 (2018).

    Article  Google Scholar 

  104. 104.

    Battaglia, C. et al. Nanoimprint lithography for high-efficiency thin-film silicon solar cells. Nano Lett. 11, 661–665 (2011).

    Article  Google Scholar 

  105. 105.

    Battaglia, C. et al. Nanomoulding of transparent zinc oxide electrodes for efficient light trapping in solar cells. Nat. Photon. 5, 535–538 (2011).

    Article  Google Scholar 

  106. 106.

    Chou, S. Y., Krauss, P. R. & Renstrom, P. J. Imprint of sub-25 nm vias and trenches in polymers. Appl. Phys. Lett. 67, 3114 (1995).

    Article  Google Scholar 

  107. 107.

    Odom, T. W. et al. Improved pattern transfer in soft lithography using composite stamps. Langmuir 18, 5314 (2002).

    Article  Google Scholar 

  108. 108.

    Yin, G. et al. Optoelectronic enhancement of ultrathin CIGS solar cells by nanophotonic contacts. Adv. Opt. Mater. 5, 1600637 (2017).

    Article  Google Scholar 

  109. 109.

    Lan H. Large-Area Nanoimprint Lithography and Applications (Intechopen, 2017).

  110. 110.

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

    Article  Google Scholar 

  111. 111.

    Würfel, U., Cuevas, A. & Würfel, P. Charge carrier separation in solar cells. IEEE J. Photovolt. 5, 461–469 (2015). Different conductivities for e/h+ is the key ingredient for charge carrier separation in solar cells. Heterojunctions might also provide passivation.

    Article  Google Scholar 

  112. 112.

    Fu, Y. et al. ZnS nanodot film as defect passivation layer for Cu(In, Ga)(S, Se)2 thin-film solar cells deposited by spray-ILGAR (Ion-Layer Gas Reaction). Adv. Ener. Mater. 1, 561–564 (2011).

    Article  Google Scholar 

  113. 113.

    Reinhard, P. et al. Alkali-templated surface nanopatterning of chalcogenide thin films: a novel approach toward solar cells with enhanced efficiency. Nano Lett. 15, 3334–3340 (2015). Introduction of local heterojunctions in passivated front surfaces of CIGS solar cells. Surface nanopatterning based on self-assembled and well-defined alkali condensate nanostructures.

    Article  Google Scholar 

  114. 114.

    Rezaei, N., Isabella, O., Procel, P., Vroon, Z. & Zeman, M. Optical study of back-contacted CIGS solar cells. Opt. Express 27, A269–A279 (2019).

    Article  Google Scholar 

  115. 115.

    Fan, S. Thermal photonics and energy applications. Joule 1, 264–273 (2017).

    Article  Google Scholar 

  116. 116.

    Reese, M. O. et al. Increasing markets and decreasing package weight for high-specific-power photovoltaics. Nat. Ener. 3, 1002–1012 (2018).

    Article  Google Scholar 

  117. 117.

    Hirst, L. C. et al. Intrinsic radiation tolerance of ultra-thin GaAs solar cells. Appl. Phys. Lett. 109, 033908 (2016).

    Article  Google Scholar 

  118. 118.

    Green, M. A. & Bremner, S. P. Energy conversion approaches and materials for high-efficiency photovoltaics. Nat. Mater. 16, 23–34 (2017).

    Article  Google Scholar 

  119. 119.

    Okada, Y. et al. Intermediate band solar cells: recent progress and future directions. Appl. Phys. Rev. 2, 021302 (2015).

    Article  Google Scholar 

  120. 120.

    Mellor, A., Hylton, N., Maier, S. & Ekins-Daukes, N. Interstitial light-trapping design for multi-junction solar cells. Sol. Energy Mater. Sol. Cells 159, 212–218 (2017).

    Article  Google Scholar 

  121. 121.

    Do, K. S. et al. Experimental and simulation study for ultrathin (~100 μm) mono crystalline silicon solar cell with 156×156 mm2 area. Met. Mater. Int. 20, 545 (2014).

    Article  Google Scholar 

  122. 122.

    Taguchi, M. et al. 24.7 % record efficiency HIT solar cell on thin silicon wafer. IEEE J. Photovolt. 4, 96–99 (2014).

    Article  Google Scholar 

  123. 123.

    Radhakrishna, H. S. et al. Heterojunction IBC solar cells on thin (< 50μm) epitaxial Si foils produced from kerfless layer transfer process. In Proc. 33rd European Photovoltaic Solar Energy Conference and Exhibition 740–744 (2017).

  124. 124.

    Danel, A. et al. Silicon heterojunction solar cells with open-circuit-voltage above 750mV. In Proc. 35th European Photovoltaic Solar Energy Conference and Exhibition 444–447 (2018).

  125. 125.

    Reuter, M., Brendle, W., Tobail, O. & Werner, J. H. 50 µm thin solar cells with 17.0% efficiency. Sol. Energy Mater. Sol. Cells 93, 704–706 (2009).

    Article  Google Scholar 

  126. 126.

    Bergmann, R., Berge, C., Rinke, T., Schmidt, J. & Werner, J. Advances in monocrystalline Si thin film solar cells by layer transfer. Sol. Energy Mater. Sol. Cells 74, 213–218 (2002).

    Article  Google Scholar 

  127. 127.

    Tang, Q. et al. Superiority of random inverted nanopyramid as efficient light trapping structure in ultrathin flexible c-Si solar cell. Renew. Ener. 133, 883–892 (2019).

    Article  Google Scholar 

  128. 128.

    Balaji, P., Dauksher, W. J., Bowden, S. G., Augusto, A. Flexible silicon heterojunction solar cells on 40 µm thin substrates. In Proc. IEEE 46th Photovoltaic Specialists Conference (PVSC) 1089–1092 (IEEE, 2019).

  129. 129.

    Glunz, S. New concepts for high-efficiency silicon solar cells. Sol. Energy Mater. Sol. Cells 90, 3276–3284 (2006).

    Article  Google Scholar 

  130. 130.

    Li, Y. et al. Quasi-Omnidirectional Ultrathin Silicon Solar Cells Realized by Industrially Compatible Processes. Adv. Electron. Mater. 5, 1800858 (2019).

    Article  Google Scholar 

  131. 131.

    Zheng, G. et al. 16.4% efficient, thin active layer silicon solar cell grown by liquid phase epitaxy. Sol. Energy Mater. Sol. Cells 40, 231–238 (1996).

    Article  Google Scholar 

  132. 132.

    Kuzma-Filipek, I. et al. 16% thin-film epitaxial silicon solar cells on 70-cm2 area with 30-µm active layer, porous silicon back reflector, and Cu-based top-contact metallization. P. rog. Photovolt. 20, 350–355 (2012).

    Article  Google Scholar 

  133. 133.

    Haase, F., Horbelt, R., Terheiden, B., Plagwitz, H. & Brendel, R. Back contact monocrystalline thin-film silicon solar cells from the porous silicon process. In Proc. The 34th IEEE Photovoltaic Specialists Conference 244–246 (2009).

  134. 134.

    Blakers, A. W. 17% Efficient thin-film silicon solar cell by liquid-phase epitaxy. Prog. Photovolt. 3, 193–195 (1995).

    Article  Google Scholar 

  135. 135.

    Kim, H. J., Depauw, V., Duerinckx, F., Beaucarne, G. & Poortmans, J. Large-area thin-film free-standing monocrystalline Si solar cells by layer transfer. In Proc. The IEEE 4th World Conference on Photovoltaic Energy Conference 984–987 (IEEE, 2006).

  136. 136.

    Hilali, M. M. et al. Light trapping in ultrathin 25 µm exfoliated Si solar cells. Appl. Opt. 53, 6140–6147 (2014).

    Article  Google Scholar 

  137. 137.

    He, J. et al. 15% Efficiency ultrathin silicon solar cells with fluorine-doped titanium oxide and chemically tailored poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) as asymmetric heterocontact. ACS Nano 13, 6356–6362 (2019).

    Article  Google Scholar 

  138. 138.

    Wolf, A., Terheiden, B. & Brendel, R. Autodiffusion: a novel method for emitter formation in crystalline silicon thin-film solar cells. Prog. Photovolt. 15, 199–210 (2007).

    Article  Google Scholar 

  139. 139.

    Duerinckx, F., Kuzma-Filipek, I., Nieuwenhuysen, K. V., Beaucarne, G. & Poortmans, J. Simulation and implementation of a porous silicon reflector for epitaxial silicon solar cells. Prog. Photovolt. 16, 399–407 (2008).

    Article  Google Scholar 

  140. 140.

    Nieuwenhuysen, K. V. et al. Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency. Thin Solid Films 518, S80–S82 (2010).

    Article  Google Scholar 

  141. 141.

    He, J. et al. Realization of 13.6% efficiency on 20 μm thick si/organic hybrid heterojunction solar cells via advanced nanotexturing and surface recombination suppression. ACS Nano 9, 6522–6531 (2015).

    Article  Google Scholar 

  142. 142.

    Zheng, S., Wenham, R. & Green, M. A. 17.6% efficient multilayer thin-film silicon solar cells deposited on heavily doped silicon substrates. Prog. Photovolt. 4, 369–373 (1996).

    Article  Google Scholar 

  143. 143.

    Jeong, S., McGehee, M. D. & Cui, Y. All-back-contact ultra-thin silicon nanocone solar cells with 13.7% power conversion efficiency. Nat. Commun. 4, 2950 (2013).

    Article  Google Scholar 

  144. 144.

    Hadibrata, W., Es, F., Yerci, S. & Turan, R. Ultrathin Si solar cell with nanostructured light trapping by metal assisted etching. Sol. Energy Mater. Sol. Cells 180, 247–252 (2018).

    Article  Google Scholar 

  145. 145.

    Wang, S. et al. Large-area free-standing ultrathin single-crystal silicon as processable materials. Nano Lett. 13, 4393–4398 (2013).

    Article  Google Scholar 

  146. 146.

    Cariou, R., Ruggeri, R., Chatterjee, P., Gentner, J. L. & Roca I Cabarrocas, P. Silicon epitaxy below 200 °C: towards thin crystalline solar cells. In Proc. SPIE Optics and Photonics 84700B (SPIE, 2012).

  147. 147.

    Xue, M. et al. Free-standing 2.7 μm thick ultrathin crystalline silicon solar cell with efficiency above 12.0%. Nano Ener. 70, 104466 (2020).

    Article  Google Scholar 

  148. 148.

    Cariou, R., Labrune, M. & Roca i Cabarrocas, P. Thin crystalline silicon solar cells based on epitaxial films grown at 165°C by RF-PECVD. Sol. Energy Mater. Sol. Cells 95, 2260–2263 (2011).

    Article  Google Scholar 

  149. 149.

    Teplin, C. W. et al. Comparison of thin epitaxial film silicon photovoltaics fabricated on monocrystalline and polycrystalline seed layers on glass. Prog. Photovolt. 23, 909–917 (2015).

    Article  Google Scholar 

  150. 150.

    Xue, M. et al. Contact selectivity engineering in a 2 μm thick ultrathin c-Si solar cell using transition-metal oxides achieving an efficiency of 10.8 %. ACS Appl. Mater. Interfaces 9, 41863–41870 (2017).

    Article  Google Scholar 

  151. 151.

    Trompoukis, C., El Daif, O., Depauw, V., Gordon, I. & Poortmans, J. Photonic assisted light trapping integrated in ultrathin crystalline silicon solar cells by nanoimprint lithography. Appl. Phys. Lett. 101, 103901 (2012).

    Article  Google Scholar 

  152. 152.

    Depauw, V., Qiu, Y., Van Nieuwenhuysen, K., Gordon, I. & Poortmans, J. Epitaxy-free monocrystalline silicon thin film: first steps beyond proof-of-concept solar cells. Prog. Photovolt. 19, 844 (2011).

    Article  Google Scholar 

  153. 153.

    Mavrokefalos, A., Han, S. E., Yerci, S., Branham, M. S. & Chen, G. Efficient light trapping in inverted nanopyramid thin crystalline silicon membranes for solar cell applications. Nano Lett. 12, 2792–2796 (2012).

    Article  Google Scholar 

  154. 154.

    Kuang, P. et al. Achieving an accurate surface profile of a photonic crystal for near-unity solar absorption in a super thin-film architecture. ACS Nano 10, 6116–6124 (2016).

    Article  Google Scholar 

  155. 155.

    Hsu, W.-C. et al. Mismatched front and back gratings for optimum light trapping in ultra-thin crystalline silicon solar cells. Opt. Commun. 377, 52–58 (2016).

    Article  Google Scholar 

  156. 156.

    Tan, X. et al. Enhancement of light trapping for ultrathin crystalline silicon solar cells. Opt. Commun. 426, 584–588 (2018).

    Article  Google Scholar 

  157. 157.

    Kim, I. et al. Silicon nanodisk array design for effective light trapping in ultrathin c-Si. Opt. Express 22, A1431–A1439 (2014).

    Article  Google Scholar 

  158. 158.

    Mallick, S. B., Agrawal, M. & Peumans, P. Optimal light trapping in ultra-thin photonic crystal crystalline silicon solar cells. Opt. Express 18, 5691–5706 (2010).

    Article  Google Scholar 

  159. 159.

    Steiner, M. A. et al. Optical enhancement of the open-circuit voltage in high quality GaAs solar cells. J. Appl. Phys. 113, 123109 (2013).

    Article  Google Scholar 

  160. 160.

    Gai, B. et al. Multilayer-grown ultrathin nanostructured GaAs solar cells as a cost-competitive materials platform for III–V photovoltaics. ACS Nano 11, 992–999 (2017).

    Article  Google Scholar 

  161. 161.

    Yang, W. et al. Ultra-thin GaAs single-junction solar cells integrated with lattice-matched ZnSe as a reflective back scattering layer. In Proc. 38th IEEE Photovoltaic Specialists Conference 978–981 (IEEE, 2012).

  162. 162.

    Vandamme, N. Nanostructured Ultrathin GaAs Solar Cells. PhD thesis, Université Paris Sud (2015); http://www.theses.fr/2015PA112111.

  163. 163.

    Sai, H., Mizuno, H., Makita, K. & Matsubara, K. Light absorption enhancement in thin-film GaAs solar cells with flattened light scattering substrates. J. Appl. Phys. 122, 123103 (2017).

    Article  Google Scholar 

  164. 164.

    Buencuerpo, J., Steiner, M. A. & Tamboli, A. C. Optically-thick 300 nm GaAs solar cells using adjacent photonic crystals. Opt. Express 28, 13845 (2020).

    Article  Google Scholar 

  165. 165.

    Grenet, L. et al. Influence of coevaporation process on CIGS solar cells with reduced absorber thickness and current enhancement with periodically textured glass substrates. Thin Solid Films 621, 188–194 (2017).

    Article  Google Scholar 

  166. 166.

    Kim, K., Park, H., Kim, W. K., Hanket, G. M. & Shafarman, W. N. Effect of reduced Cu(InGa)(SeS)2 thickness using three-step H2Se/Ar/H2S reaction of Cu-In-Ga metal precursor. IEEE J. Photovolt. 3, 446–450 (2013).

    Article  Google Scholar 

  167. 167.

    Mansfield, L. M. et al. Efficiency increased to 15.2% for ultra-thin Cu(In, Ga)Se2 solar cells. Prog. Photovolt. 26, 949–954 (2018).

    Article  Google Scholar 

  168. 168.

    Salome, P. M. P. et al. Passivation of interfaces in thin film solar cells: understanding the effects of a nanostructured rear point contact layer. Adv. Mater. Interfaces 5, 1701101 (2018).

    Article  Google Scholar 

  169. 169.

    Shin, M. J. et al. Semi-transparent photovoltaics using ultra-thin Cu(In, Ga)Se2 absorber layers prepared by single-stage co-evaporation. Solar Ener. 181, 276–284 (2019).

    Article  Google Scholar 

  170. 170.

    Kim, K. & Shafarman, W. N. Alternative device structures for CIGS-based solar cells with semi-transparent absorbers. Nano Ener. 30, 488–493 (2016).

    Article  Google Scholar 

  171. 171.

    Dahan, N. et al. Using radiative transfer equation to model absorption by thin Cu(In, Ga)Se2 solar cells with Lambertian back reflector. Opt. Express 21, 2563–2580 (2013).

    Article  Google Scholar 

  172. 172.

    Yin, G., Manley, P. & Schmid, M. Light trapping in ultrathin CuIn1-xGaxSe2 solar cells by dielectric nanoparticles. Solar Ener. 163, 443–452 (2018).

    Article  Google Scholar 

  173. 173.

    Sasihithlu, K., Dahan, N. & Greffet, J. J. Light trapping in ultrathin CIGS solar cell with absorber thickness of 0.1 µm. IEEE J. Photovolt. 8, 621–625 (2018).

    Article  Google Scholar 

  174. 174.

    Allen, T. G. et al. A low resistance calcium/reduced titania passivated contact for high efficiency crystalline silicon solar cells. Adv. Ener. Mater. 7, 1602606 (2017).

    Article  Google Scholar 

  175. 175.

    Yin, X. et al. 19.2% Efficient InP heterojunction solar cell with electron-selective TiO2 contact. ACS Photo. 1, 1245 (2014).

    Article  Google Scholar 

  176. 176.

    Hsu, W. et al. Electron-selective TiO2 contact for Cu(In, Ga)Se2 solar cells. Sci. Rep. 5, 16028 (2015).

    Article  Google Scholar 

  177. 177.

    Yablonovitch, E., Gmitter, T., Swanson, R. M. & Kwark, Y. H. A 720 mV open circuit voltage SiOx:c‐Si:SiOx double heterostructure solar cell. Appl. Phys. Lett. 47, 1211–1213 (1985).

    Article  Google Scholar 

  178. 178.

    Feldmann, F. et al. Efficient carrier-selective p- and n-contacts for Si solar cells. Sol. Energy Mater. Sol. Cells 131, 100–104 (2014).

    Article  Google Scholar 

  179. 179.

    Richter, A. et al. n‐Type Si solar cells with passivating electron contact: identifying sources for efficiency limitations by wafer thickness and resistivity variation. Sol. Energy Mater. Sol. Cells 173, 96–105 (2017).

    Article  Google Scholar 

  180. 180.

    Battaglia, C. et al. Hole selective MoOx contact for silicon solar cells. Nano Lett. 14, 967–971 (2014).

    Article  Google Scholar 

  181. 181.

    Geissbühler, J. et al. 22.5 % efficient silicon heterojunction solar cell with molybdenum oxide hole collector. Appl. Phys. Lett. 107, 081601 (2015).

    Article  Google Scholar 

  182. 182.

    Bullock, J. et al. Efficient silicon solar cells with dopant-free asymmetric heterocontacts. Nat. Ener. 1, 15031 (2016).

    Article  Google Scholar 

  183. 183.

    Wei, S. & Zunger, A. Band offsets and optical bowings of chalcopyrites and Zn‐based II‐VI alloys. J. Appl. Phys. 78, 3846–3856 (1995).

    Article  Google Scholar 

  184. 184.

    Feurer, T. et al. Progress in thin film CIGS photovoltaics – research and development, manufacturing, and applications. Prog. Photovolt. 7, 645–667 (2016).

    Google Scholar 

  185. 185.

    Green, M. A. & Keevers, M. J. Optical properties of intrinsic silicon at 300K. Prog. Photovolt. 3, 189–192 (1995).

    Article  Google Scholar 

  186. 186.

    Yablonovitch, E. Statistical ray optics. J. Opt. Soc. Am. 71, 899–907 (1982).

    Article  Google Scholar 

  187. 187.

    Green, M. A. Lambertian light trapping in textured solar cells and light-emitting diodes: analytical solutions. Prog. Photovolt. 10, 235–241 (2002).

    Article  Google Scholar 

  188. 188.

    Collin, S. & Giteau, M. New limits for light-trapping with multi-resonant absorption. In Proc. IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC-7) 3460–3462 (IEEE, 2018).

  189. 189.

    Wang, K. X., Guo, Y. & Fan, S. Wave optics light-trapping theory: mathematical justification and ultimate limit on enhancement. J. Opt. Soc. Am. B 36, 2414–2422 (2019).

    Article  Google Scholar 

  190. 190.

    Lipovšek, B., Krč, J. & Topič, M. Optimization of microtextured light-management films for enhanced light trapping in organic solar cells under perpendicular and oblique illumination conditions. IEEE J. Photovolt. 4, 639–646 (2014).

    Article  Google Scholar 

  191. 191.

    Eisenhauer, D., Trinh, C. T., Amkreutz, D. & Becker, C. Light management in crystalline silicon thin-film solar cells with imprint-textured glass superstrate. Sol. Energy Mater. Sol. Cells 200, 109928 (2019).

    Article  Google Scholar 

  192. 192.

    Kosten, E. D., Kayes, B. M. & Atwater, H. A. Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells. Energy Environ. Sci. 7, 1907–1912 (2014).

    Article  Google Scholar 

  193. 193.

    Kosten, E. D., Newman, B. K., Lloyd, J. V., Polman, A. & Atwater, H. Limiting light escape angle in silicon photovoltaics: ideal and realistic cells. IEEE J. Photovolt. 5, 61–69 (2015).

    Article  Google Scholar 

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Acknowledgements

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). https://doi.org/10.1038/s41560-020-00714-4

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