Skip to main content

Thank you for visiting nature.com. 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:

Defect compensation in formamidinium–caesium perovskites for highly efficient solar mini-modules with improved photostability

Nature Energy volume 6, pages 633–641 (2021)Cite this article

Subjects

Abstract

Formamidinium–caesium mixed-cation perovskites have shown better thermal stability than their methylammonium-containing counterparts but they suffer from photoinstability induced by iodide migration and phase segregation. Here we improve their photostability by adding slightly excessive AX (at a molar percentage of 0.25% to Pb2+ ions), where A is formamidinium or caesium and X is iodine. The excessive AX does not improve the initial solar cell efficiency. It compensates iodide vacancies and suppresses ion migration and defects generation during long-term illumination by around tenfold compared with AX-deficient devices. Consequently, generation of hole traps and phase segregation is impeded, with the former limiting solar cell efficiency after degradation. The perovskite mini-modules reached a certified stabilized efficiency of 18.6% with an aperture area of ~30 cm2, corresponding to an active area efficiency of 20.2%. The mini-module maintains 93.6% of the initial efficiency after continuous operation under 1 sun illumination for >1,000 h at 50 ± 5 °C in air.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Fig. 1: Fabrication of FACs perovskites by blading.
Fig. 2: Excessive AX improves photostability of devices by maintaining fast photocarrier transport.
Fig. 3: FACs perovskite degradation mechanism and defect compensation by excessive AX.
Fig. 4: Excessive AX for high-performance FACs perovskite modules.

Similar content being viewed by others

Data availability

All data generated or analysed during this study are included in the article and its Supplementary Information. Source data are provided with this paper.

References

  1. Best Research‐Cell Efficiency Chart (NREL, 2020); https://www.nrel.gov/pv/cell-efficiency.html

  2. Rong, Y. et al. Challenges for commercializing perovskite solar cells. Science 361, eaat8235 (2018).

    Article  Google Scholar 

  3. Bai, S. et al. Planar perovskite solar cells with long-term stability using ionic liquid additives. Nature 571, 245–250 (2019).

    Article  Google Scholar 

  4. Turren-Cruz, S.-H., Hagfeldt, A. & Saliba, M. Methylammonium-free, high-performance, and stable perovskite solar cells on a planar architecture. Science 362, 449–453 (2018).

    Article  Google Scholar 

  5. Wang, L. et al. A Eu3+–Eu2+ ion redox shuttle imparts operational durability to Pb–I perovskite solar cells. Science 363, 265–270 (2019).

    Article  Google Scholar 

  6. Wang, Y. et al. Stabilizing heterostructures of soft perovskite semiconductors. Science 365, 687–691 (2019).

    Article  Google Scholar 

  7. Bi, E. et al. Efficient perovskite solar cell modules with high stability enabled by iodide diffusion barriers. Joule 3, 2748–2760 (2019).

    Article  Google Scholar 

  8. Liu, Z. et al. A holistic approach to interface stabilization for efficient perovskite solar modules with over 2,000-hour operational stability. Nat. Energy 5, 596–604 (2020).

    Article  Google Scholar 

  9. 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).

    Article  Google Scholar 

  10. Tan, S. et al. Shallow iodine defects accelerate the degradation of α-phase formamidinium perovskite. Joule 4, 2426–2442 (2020).

    Article  Google Scholar 

  11. Li, N. et al. Microscopic degradation in formamidinium–cesium lead iodide perovskite solar cells under operational stressors. Joule 4, 1743–1758 (2020).

    Article  Google Scholar 

  12. Slotcavage, D. J., Karunadasa, H. I. & McGehee, M. D. Light-induced phase segregation in halide-perovskite absorbers. ACS Energy Lett. 1, 1199–1205 (2016).

    Article  Google Scholar 

  13. Brivio, F., Caetano, C. & Walsh, A. Thermodynamic origin of photoinstability in the CH3NH3Pb (I1–xBrx)3 hybrid halide perovskite alloy. J. Phys. Chem. Lett. 7, 1083–1087 (2016).

    Article  Google Scholar 

  14. Li, Z. et al. Stabilizing perovskite structures by tuning tolerance factor: formation of formamidinium and cesium lead iodide solid-state alloys. Chem. Mater. 28, 284–292 (2016).

    Article  Google Scholar 

  15. Lee, J. W. et al. Formamidinium and cesium hybridization for photo‐and moisture‐stable perovskite solar cell. Adv. Energy Mater. 5, 1501310 (2015).

    Article  Google Scholar 

  16. Charles, B. et al. Phase behavior and substitution limit of mixed cesium–formamidinium lead triiodide perovskites. Chem. Mater. 32, 2282–2291 (2020).

    Article  Google Scholar 

  17. Deng, Y. et al. Tailoring solvent coordination for high-speed, room-temperature blading of perovskite photovoltaic films. Sci. Adv. 5, eaax7537 (2019).

    Article  Google Scholar 

  18. Deng, Y. et al. Reduced self-doping of perovskites induced by short annealing for efficient solar modules. Joule 4, 1949–1960 (2020).

    Article  Google Scholar 

  19. Chen, B. et al. Grain engineering for perovskite/silicon monolithic tandem solar cells with efficiency of 25.4%. Joule 3, 177–190 (2019).

    Article  Google Scholar 

  20. Lee, J.-W. et al. 2D Perovskite stabilized phase-pure formamidinium perovskite solar cells. Nat. Commun. 9, 3021 (2018).

    Article  Google Scholar 

  21. Jiang, Q. et al. Surface passivation of perovskite film for efficient solar cells. Nat. Photon. 13, 460–466 (2019).

    Article  Google Scholar 

  22. Zheng, X. et al. Managing grains and interfaces via ligand anchoring enables 22.3%-efficiency inverted perovskite solar cells. Nat. Energy 5, 131–140 (2020).

    Article  Google Scholar 

  23. Lee, M. M., Teuscher, J., Miyasaka, T., Murakami, T. N. & Snaith, H. J. Efficient hybrid solar cells based on meso-superstructured organometal halide perovskites. Science 338, 643–647 (2012).

    Article  Google Scholar 

  24. Jahandar, M. et al. High-performance CH3NH3PbI3-inverted planar perovskite solar cells with fill factor over 83% via excess organic/inorganic halide. ACS Appl. Mater. Interfaces 9, 35871–35879 (2017).

    Article  Google Scholar 

  25. Son, D.-Y. et al. Self-formed grain boundary healing layer for highly efficient CH3NH3PbI3 perovskite solar cells. Nat. Energy 1, 1–8 (2016).

    Article  Google Scholar 

  26. Chen, B. et al. Synergistic effect of elevated device temperature and excess charge carriers on the rapid light‐induced degradation of perovskite solar cells. Adv. Mater. 31, 1902413 (2019).

    Article  Google Scholar 

  27. 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).

    Article  Google Scholar 

  28. Tumen‐Ulzii, G. et al. Detrimental effect of unreacted PbI2 on the long‐term stability of perovskite solar cells. Adv. Mater. 32, 1905035 (2020).

    Article  Google Scholar 

  29. Roose, B., Dey, K., Chiang, Y.-H., Friend, R. H. & Stranks, S. D. A critical assessment of the use of excess lead iodide in lead halide perovskite solar cells. J. Phys. Chem. Lett. 11, 6505–6512 (2020).

    Article  Google Scholar 

  30. 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).

    Article  Google Scholar 

  31. Fu, F. et al. I2 vapor-induced degradation of formamidinium lead iodide based perovskite solar cells under heat–light soaking conditions. Energy Environ. Sci. 12, 3074–3088 (2019).

    Article  Google Scholar 

  32. Tao, S. et al. Absolute energy level positions in tin-and lead-based halide perovskites. Nat. Commun. 10, 2560 (2019).

    Article  Google Scholar 

  33. Game, O. S., Buchsbaum, G. J., Zhou, Y., Padture, N. P. & Kingon, A. I. Ions matter: description of the anomalous electronic behavior in methylammonium lead halide perovskite devices. Adv. Funct. Mater. 27, 1606584 (2017).

    Article  Google Scholar 

  34. Domanski, K. et al. Migration of cations induces reversible performance losses over day/night cycling in perovskite solar cells. Energy Environ. Sci. 10, 604–613 (2017).

    Article  Google Scholar 

  35. Lin, Y. et al. Excess charge-carrier induced instability of hybrid perovskites. Nat. Commun. 9, 4981 (2018).

    Article  Google Scholar 

  36. Draguta, S. et al. Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites. Nat. Commun. 8, 200 (2017).

    Article  Google Scholar 

  37. Motti, S. G. et al. Controlling competing photochemical reactions stabilizes perovskite solar cells. Nat. Photon. 13, 532–539 (2019).

    Article  Google Scholar 

  38. Ni, Z. et al. Revealing the Chemical Nature of Defects in Metal Halide Perovskites (2020).

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

    Article  Google Scholar 

  40. Motti, S. G. et al. Defect activity in lead halide perovskites. Adv. Mater. 31, 1901183 (2019).

    Article  Google Scholar 

  41. Du, M.-H. Density functional calculations of native defects in CH3NH3PbI3: effects of spin–orbit coupling and self-interaction error. J. Phys. Chem. Lett. 6, 1461–1466 (2015).

    Article  Google Scholar 

  42. Di Girolamo, D. et al. Ion migration‐induced amorphization and phase segregation as a degradation mechanism in planar perovskite solar cells. Adv. Energy Mater. 10, 2000310 (2020).

    Article  Google Scholar 

  43. Almora, O. et al. Capacitive dark currents, hysteresis, and electrode polarization in lead halide perovskite solar cells. J. Phys. Chem. Lett. 6, 1645–1652 (2015).

    Article  Google Scholar 

  44. Bertoluzzi, L. et al. Mobile ion concentration measurement and open-access band diagram simulation platform for halide perovskite solar cells. Joule 4, 109–127 (2020).

    Article  Google Scholar 

  45. Kim, G. Y. et al. Large tunable photoeffect on ion conduction in halide perovskites and implications for photodecomposition. Nat. Mater. 17, 445–449 (2018).

    Article  Google Scholar 

  46. Albertus, P., Babinec, S., Litzelman, S. & Newman, A. Status and challenges in enabling the lithium metal electrode for high-energy and low-cost rechargeable batteries. Nat. Energy 3, 16–21 (2018).

    Article  Google Scholar 

  47. Wang, H., Jang, Y. I., Huang, B., Sadoway, D. R. & Chiang, Y. M. TEM study of electrochemical cycling‐induced damage and disorder in LiCoO2 cathodes for rechargeable lithium batteries. J. Electrochem. Soc. 146, 473 (1999).

    Article  Google Scholar 

  48. Green, M. et al. Solar cell efficiency tables (version 57). Prog. Photovolt. 29, 3–15 (2020).

  49. Hong, Z., Huang, Z. & Zeng, X. Utilization of copper phthalocyanine and bathocuproine as an electron transport layer in photovoltaic cells with copper phthalocyanine/buckminsterfullerene heterojunctions: thickness effects on photovoltaic performances. Thin Solid Films 515, 3019–3023 (2007).

    Article  Google Scholar 

  50. Prasanna, R. et al. Design of low bandgap tin–lead halide perovskite solar cells to achieve thermal, atmospheric and operational stability. Nat. Energy 4, 939–947 (2019).

    Article  Google Scholar 

  51. Xiao, Z. et al. Unraveling the hidden function of a stabilizer in a precursor in improving hybrid perovskite film morphology for high efficiency solar cells. Energy Environ. Sci. 9, 867–872 (2016).

    Article  Google Scholar 

Download references

Acknowledgements

This work was supported by University of North Carolina at Chapel Hill. Part of the material is based on work supported by the Office of Naval Research under contract no. N68335-20-C-0390 through a subcontract from Perotech Inc. This work was performed, in part, at the Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), which is supported by the National Science Foundation (grant ECCS-1542015), as part of the National Nanotechnology Coordinated Infrastructure (NNCI).

Author information

Authors and Affiliations

  1. Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

    Yehao Deng, Shuang Xu, Shangshang Chen, Xun Xiao, Jingjing Zhao & Jinsong Huang

  2. Perotech Inc, Chapel Hill, NC, USA

    Yehao Deng

Authors
  1. Yehao Deng
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Shuang Xu
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Shangshang Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Xun Xiao
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Jingjing Zhao
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jinsong Huang
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

J.H. and Y.D. conceived the idea. Y.D. designed the experiments, conducted most of the device fabrication and measurement, and prepared the modules for certification. Y.D. and S.X. conducted the photoluminescence studies. S.C. captured the SEM images. X.X. and J.Z. performed the XRD measurements. Y.D. and J.H. wrote the paper, and all authors reviewed the paper.

Corresponding author

Correspondence to Jinsong Huang.

Ethics declarations

Competing interests

J.H. and Y.D. are inventors on a patent application related to this work filed by University of North Carolina Chapel Hill (US 63/060,451, filed 03 August 2020). J.H. has disclosed a significant financial interest in Perotech Inc. The other authors declare no competing interests.

Additional information

Peer review information Nature Energy thanks Jin-Wook Lee, Nam-Gyu Park and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–25.

Reporting summary

Supplementary Data 1

Source data for statistics in Supplementary Figs. 4, 6, 7, 8, 10, 16, 19.

Source data

Source Data Fig. 2

Source data for statistics plot9.

Source Data Fig. 3

Source data for statistics plot9.

Source Data Fig. 4

Source data for statistics plot9.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Deng, Y., Xu, S., Chen, S. et al. Defect compensation in formamidinium–caesium perovskites for highly efficient solar mini-modules with improved photostability. Nat Energy 6, 633–641 (2021). https://doi.org/10.1038/s41560-021-00831-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41560-021-00831-8

This article is cited by

Search

Advanced search

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