Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%


Improving the photoconversion efficiency of silicon solar cells is crucial to further the deployment of renewable electricity. Essential device properties such as lifetime, series resistance and optical properties must be improved simultaneously to reduce recombination, resistive and optical losses. Here, we use industrially compatible processes to fabricate large-area silicon solar cells combining interdigitated back contacts and an amorphous silicon/crystalline silicon heterojunction. The photoconversion efficiency is over 26% with a 180.4 cm2 designated area, which is an improvement of 2.7% relative to the previous record efficiency of 25.6%. The cell was analysed to characterize lifetime, quantum efficiency, and series resistance, which are essential elements for conversion efficiency. Finally, a loss analysis pinpoints a path to approach the theoretical conversion efficiency limit of Si solar cells, 29.1%.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Schematic image and IV curve of the HJ-IBC cell.
Figure 2: Schematic images of typical c-Si solar cells and record efficiencies.
Figure 3: Quantum efficiency and reflection spectra.
Figure 4: Extraction of series resistance and ideality factor using Suns-V OC.
Figure 5: Effective lifetime and implied IV of the practical efficiency limit.
Figure 6: Summary of loss elements.

Similar content being viewed by others


  1. BP Statistical Review of World Energy 2016 (BP, 2016);

  2. World Energy Outlook 2015 (IEA, 2015);

  3. Solar Quarterly Market Update—China, United States and Japan to Lead Global Solar Installation in 2016 (Mercom Capital Group, 2016);

  4. 2014 Outlook: Let the Second Gold Rush Begin (Deutsche Bank, 2014);

  5. Technology Roadmap for Photovoltaic (ITRPV): 2015 Results Including Maturity Report (VDMA Photovoltaic Equipment, 2016);

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

    Article  Google Scholar 

  7. Best Research-Cell Efficiencies (NREL, 2016);

  8. Green, M. A., Emery, K., Hishikawa, Y., Warta, W. & Dunlop, E. D. Solar cell efficiency tables (version 48). Prog. Photovolt. Res. Appl. 24, 905–913 (2016).

    Article  Google Scholar 

  9. Taguchi, M. et al. HIT cells: high efficiency crystalline Si cells with novel structure. Prog. Photovolt. 8, 492–502 (2000).

    Article  Google Scholar 

  10. Lammert, M. D. & Schwartz, R. J. The interdigitated back contact solar cell: a silicon solar cell for use inconcentrated sunlight. IEEE Trans. Electron Devices 24, 337–341 (1977).

    Article  Google Scholar 

  11. Swanson, R. M. et al. Point-contact silicon solar cells. IEEE Trans. Electron Devices 31, 661–664 (2005).

    Article  Google Scholar 

  12. Masuko, K. et al. Achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell. IEEE J. Photovolt. 4, 1433–1435 (2014).

    Article  Google Scholar 

  13. Smith, D. D. et al. Silicon solar cells with total area efficiency above 25%. In 2016 IEEE 43rd Photovoltaic Spec. Conf. 3351–3355 (IEEE, 2016).

  14. Adachi, D., Hernandez, J. L. & Yamamoto, K. Impact of carrier recombination on fill factor for large area heterojunction crystalline Si solar cell with 25.1% efficiency. Appl. Phys. Lett. 107, 233506 (2015).

    Article  Google Scholar 

  15. Green, M. A., Emery, K., Hishikawa, Y., Warta, D. & Dunlop, E. D. Solar cell efficiency tables (version 39). Prog. Photovolt. Res. Appl. 20, 12–20 (2012).

    Article  Google Scholar 

  16. Kerr, M. J., Cuevas, A. & Campbel, P. Limiting efficiency of crystalline silicon solar cells due to Coulomb-enhanced Auger recombination. Prog. Photovolt. Res. Appl. 11, 97–104 (2003).

    Article  Google Scholar 

  17. 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 

  18. 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 

  19. Hernandez, J. L. et al. High efficiency silver-free heterojunction silicon solar cell. Jpn. J. Appl. Phys. 51, 10NB04 (2012).

    Article  Google Scholar 

  20. Hernandez, J. L. High efficiency copper electroplated heterojunction solar cells. In Proc. 27th EUPVSEC 655–656 (WIP, 2012).

  21. Hernandez, J. L. et al. High efficiency copper electroplated heterojunction solar cells and modules—The path towards 25% cell efficiency. In Proc. 28th EUPVSEC 741–743 (WIP, 2014).

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

    Google Scholar 

  23. Franklin, E. et al. Design, fabrication and characterisation of a 24.4% efficient interdigitated back contact solar cell. Prog. Photovolt. Res. Appl. 24, 411–427 (2014).

    Article  Google Scholar 

  24. Dingemans, G. & Kessels, W. M. M. Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells. J. Vac. Sci. Technol. A 30, 040802 (2012).

    Article  Google Scholar 

  25. Green, M. A. The Passivated Emitter and Rear Cell (PERC): from conception to mass production. Sol. Energy Mater. Sol. Cells 143, 190 (2015).

    Article  Google Scholar 

  26. Green, M. A. The path to 25% silicon solar cell efficiency: history of silicon cell evolution. Prog. Photovolt. Res. Appl. 17, 183–189 (2009).

    Article  Google Scholar 

  27. Zhang, S. et al. 335 watt world record p-type mono-crystalline module with 20.6% efficient PERC solar cells. IEEE J. Photovolt. 6, 145–152 (2016).

    Article  Google Scholar 

  28. Richter, A. et al. Silicon solar cells with full-area passivated rear contacts: influence of wafer resistivity on device performance on a 25% efficiency level. In 26th PVSEC (2016);

  29. Harrisona, S. et al. Back contact heterojunction solar cells patterned by laser ablation. Energy Procedia 92, 730–737 (2016).

    Article  Google Scholar 

  30. Desrues, T., De Vecchi, S., D’Alonzo, G., Muñoz, D. & Ribeyron, P.-J. Influence of the emitter coverage on interdigitated back contact (IBC) silicon hetero-junction (SHJ) solar cells. In Proc. 40th IEEE Photovoltaic Spec. Conf. 857–886 (IEEE, 2014).

  31. Lee, S. Y. et al. Analysis of a-Si:H/TCO contact resistance for the Si heterojunction back-contact solar cell. Sol. Energy Mater. Sol. Cells 120, 412–416 (2014).

    Article  Google Scholar 

  32. Tomasi, A. et al. Backcontacted silicon heterojunction solar cells with efficiency > 21%. IEEE J. Photovolt. 4, 1046–1054 (2014).

    Article  Google Scholar 

  33. Mingirulli, N. et al. Efficient interdigitated back-contacted silicon heterojunction solar cells. Phys. Status Solidi 5, 159–161 (2011).

    Google Scholar 

  34. Nakamura, J. et al. Development of heterojunction back contact Si solar cells. IEEE J. Photovolt. 4, 1491–1495 (2014).

    Article  Google Scholar 

  35. Salomon, B. P. et al. Back-contacted silicon heterojunction solar cells: optical-loss analysis and mitigation. IEEE J. Photovolt. 5, 1293–1303 (2015).

    Article  Google Scholar 

  36. Aberle, A. G. Surface passivation of crystalline silicon solar cells: a review. Prog. Photovolt. 8, 473–487 (2000).

    Article  Google Scholar 

  37. Wang, E. Y., Yu, F. T. S., Sims, V. L., Brandhorst, E. W. & Broder, J. D. Optimum design of anti-reflection coating for silicon solar cells. In 10th IEEE Photovoltaic Spec. Conf. 168–171 (IEEE, 1973).

  38. Fields, J. D. et al. The formation mechanism for printed silver-contacts for silicon solar cells. Nat. Commun. 7, 11143 (2016).

    Article  Google Scholar 

  39. Zhang, X., Wan, Y., Bullock, J., Allen, T. & Cuevas, A. Low resistance Ohmic contact to p-type crystalline silicon via nitrogen-doped copper oxide films. Appl. Phys. Lett. 109, 052102 (2016).

    Article  Google Scholar 

  40. Frühaufa, F., Sayadb, Y. & Breitensteina, O. Description of the local series resistance of real solar cells by separate horizontal and vertical components. Sol. Energy Mater. Sol. Cells 154, 23–34 (2016).

    Article  Google Scholar 

  41. Sinton, R. A. & Cuevas, A. A quasi-steady-state open-circuit voltage method for solar cell characterization. In 16th Eur. Photovoltaic Solar Energy Conf. 1152–1155 (WIP-Renewable Energies, 2000).

  42. Richter, A., Glunz, S. W., Werner, F., Schmidt, J. & Cuevas, A. Improved quantitative description of Auger recombination in crystalline silicon. Phys. Rev. B 86, 165202 (2012).

    Article  Google Scholar 

  43. Cuevas, A. & Macdonald, D. Measuring and interpreting the lifetime of silicon wafers. Sol. Energy 76, 255–262 (2004).

    Article  Google Scholar 

  44. Glunz, S. W., Nekarda, J., Mackel, H. & Cuevas, A. Analyzing back contacts of silicon solar cells by Suns-Voc-measurements at high illumination densities. In 22nd Eur. Photovoltaic Solar Energy Conf. 849–853 (WIP-Renewable Energies, 2007).

  45. Chavali, R. V. K. et al. A generalized theory explains the anomalous Suns–Voc response of Si heterojunction solar cells. IEEE J. Photovolt. 7, 169–176 (2016).

    Article  Google Scholar 

  46. Swanson, A. Approaching the 29% limit efficiency of silicon solar cells. In Proc. 31th PVSC, Colorado Springs 889–895 (Drupal, 2005).

Download references


This work was supported in part by the New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry of Japan.

Author information

Authors and Affiliations



K.Yoshikawa designed the experiments and analysed the data. D.A. and K.Yamamoto supervised the study. K.Yoshikawa., H.K., W.Y., T.I., K.K., K.N., T.U. and M.K. contributed to development of the HJ-IBC cell, optimization of optical properties, passivation quality and resistivity. K.Yoshikawa, D.A. and K.Yamamoto wrote the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Kunta Yoshikawa.

Ethics declarations

Competing interests

The authors are employees of Kaneka Corporation.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yoshikawa, K., Kawasaki, H., Yoshida, W. et al. Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%. Nat Energy 2, 17032 (2017).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing