Simplified interconnection structure based on C60/SnO2-x for all-perovskite tandem solar cells


The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO2–x (0 < x < 1) layer. The C60 layer is unintentionally n-doped by iodine ions from the perovskite and thus acts as an effective electron collecting layer. The SnO2–x layer, formed by the incomplete oxidization of tin (x = 1.76), has ambipolar carrier transport property enabled by the presence of a large density of Sn2+. The C60/SnO1.76 ICL forms Ohmic contacts with both wide and narrow bandgap perovskite subcells with low contact resistivity. The ICL boosts the efficiencies of small-area tandem cells (5.9 mm2) and large-area tandem cells (1.15 cm2) to 24.4% and 22.2%, respectively. The tandem cells remain 94% of its initial efficiency after continues 1-sun illumination for 1,000 h.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Design of C60/SnO2−x structured ICLs for monolithic all-perovskite tandem solar cells.
Fig. 2: Ambipolar property of LT-ALD SnO1.76.
Fig. 3: Optical and electronic properties of LT-ALD SnO1.76 and energy diagram of C60/SnO1.76 ICLs.
Fig. 4: Photovoltaic performance of monolithic all-perovskite tandem solar cells with C60/SnO1.76 ICLs.

Data availability

All data generated or analysed during this study are included in the published article and its Supplementary Information and Source Data files.


  1. 1.

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

    Google Scholar 

  2. 2.

    Han, Q. et al. High-performance perovskite/Cu(In,Ga)Se2 monolithic tandem solar cells. Science 361, 904–908 (2018).

    Google Scholar 

  3. 3.

    Chen, C.-C. et al. Perovskite/polymer monolithic hybrid tandem solar cells utilizing a low-temperature, full solution process. Mater. Horiz. 2, 203–211 (2015).

    Google Scholar 

  4. 4.

    Lee, J.-W. et al. Halide perovskites for tandem solar cells. J. Phys. Chem. Lett. 8, 1999–2011 (2017).

    Google Scholar 

  5. 5.

    Eperon, G. E. et al. Perovskite-perovskite tandem photovoltaics with optimized band gaps. Science 354, 861–865 (2016).

    Google Scholar 

  6. 6.

    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).

    Google Scholar 

  7. 7.

    Sadhanala, A. et al. Blue-green color tunable solution processable organolead chloride–bromide mixed halide perovskites for optoelectronic applications. Nano Lett. 15, 6095–6101 (2015).

    Google Scholar 

  8. 8.

    Hao, F., Stoumpos, C. C., Chang, R. P. H. & Kanatzidis, M. G. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. J. Am. Chem. Soc. 136, 8094–8099 (2014).

    Google Scholar 

  9. 9.

    McMeekin, D. P. et al. A mixed-cation lead mixed-halide perovskite absorber for tandem solar cells. Science 351, 151–155 (2016).

    Google Scholar 

  10. 10.

    Jeon, N. J. et al. Solvent engineering for high-performance inorganic–organic hybrid perovskite solar cells. Nat. Mater. 13, 897–903 (2014).

    Google Scholar 

  11. 11.

    Zhao, D. et al. Efficient two-terminal all-perovskite tandem solar cells enabled by high-quality low-bandgap absorber layers. Nat. Energy 3, 1093–1100 (2018).

    Google Scholar 

  12. 12.

    Palmstrom, A. F. et al. Enabling flexible all-perovskite tandem solar cells. Joule 3, 2193–2204 (2019).

    Google Scholar 

  13. 13.

    Tong, J. et al. Carrier lifetimes of >1 μs in Sn-Pb perovskites enable efficient all-perovskite tandem solar cells. Science 364, 475–479 (2019).

    Google Scholar 

  14. 14.

    Lin, R. et al. Monolithic all-perovskite tandem solar cells with 24.8% efficiency exploiting comproportionation to suppress Sn(II) oxidation in precursor ink. Nat. Energy 4, 864–873 (2019).

    Google Scholar 

  15. 15.

    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).

    Google Scholar 

  16. 16.

    Shao, Y., Xiao, Z., Bi, C., Yuan, Y. & Huang, J. Origin and elimination of photocurrent hysteresis by fullerene passivation in CH3NH3PbI3 planar heterojunction solar cells. Nat. Commun. 5, 5784 (2014).

    Google Scholar 

  17. 17.

    Wojciechowski, K. et al. C60 as an efficient n-type compact layer in perovskite solar cells. J. Phys. Chem. Lett. 6, 2399–2405 (2015).

    Google Scholar 

  18. 18.

    Xu, J. et al. Perovskite–fullerene hybrid materials suppress hysteresis in planar diodes. Nat. Commun. 6, 7081 (2015).

    Google Scholar 

  19. 19.

    Yoon, H., Kang, S. M., Lee, J.-K. & Choi, M. Hysteresis-free low-temperature-processed planar perovskite solar cells with 19.1% efficiency. Energy Environ. Sci. 9, 2262–2266 (2016).

    Google Scholar 

  20. 20.

    Baena, J. P. C. et al. Highly efficient planar perovskite solar cells through band alignment engineering. Energy Environ. Sci. 8, 2928–2934 (2015).

    Google Scholar 

  21. 21.

    Hu, T. et al. Indium‐free perovskite solar cells enabled by impermeable tin‐oxide electron extraction layers. Adv. Mater. 29, 1606656 (2017).

    Google Scholar 

  22. 22.

    Kílíç, C. & Zunger, A. Origins of coexistence of conductivity and transparency in SnO2. Phys. Rev. Lett. 88, 095501 (2002).

    Google Scholar 

  23. 23.

    Zhu, Z. et al. Enhanced efficiency and stability of inverted perovskite solar cells using highly crystalline SnO2 nanocrystals as the robust electron‐transporting layer. Adv. Mater. 28, 6478–6484 (2016).

    Google Scholar 

  24. 24.

    Rao, H.-S. et al. Improving the extraction of photogenerated electrons with SnO2 nanocolloids for efficient planar perovskite solar cells. Adv. Funct. Mater. 25, 7200–7207 (2015).

    Google Scholar 

  25. 25.

    Yang, G. et al. Effective carrier-concentration tuning of SnO2 quantum dot electron-selective layers for high-performance planar perovskite solar cells. Adv. Mater. 30, 1706023 (2018).

    Google Scholar 

  26. 26.

    Jarzebski, Z. M. & Marton, J. P. Physical properties of SnO2 materials: II. Electrical properties. J. Electrochem. Soc. 123, 299C–310C (1976).

    Google Scholar 

  27. 27.

    Li, C. et al. Reducing saturation‐current density to realize high‐efficiency low‐bandgap mixed tin–lead halide perovskite solar cells. Adv. Energy Mater. 9, 1803135 (2019).

    Google Scholar 

  28. 28.

    Zhao, D. et al. Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells. Nat. Energy 2, 17018 (2017).

    Google Scholar 

  29. 29.

    You, J. et al. A polymer tandem solar cell with 10.6% power conversion efficiency. Nat. Commun. 4, 1446 (2013).

    Google Scholar 

  30. 30.

    Dou, L. et al. Tandem polymer solar cells featuring a spectrally matched low-bandgap polymer. Nat. Photonics 6, 180–185 (2012).

    Google Scholar 

  31. 31.

    Chou, C.-H., Kwan, W. L., Hong, Z., Chen, L.-M. & Yang, Y. A metal‐oxide interconnection layer for polymer tandem solar cells with an inverted architecture. Adv. Mater. 23, 1282–1286 (2011).

    Google Scholar 

  32. 32.

    Zhang, K. et al. High‐performance polymer tandem solar cells employing a new n‐type conjugated polymer as an interconnecting layer. Adv. Mater. 28, 4817–4823 (2016).

    Google Scholar 

  33. 33.

    R. J Booth H. C Starkie M. C. R Symons R. S Eachus 1973 Unstable intermediates. Part CXXXV. The formation of Sn3+ and Pb3+ centres in irradiated tin and lead salts, and their electron spin resonance parameters J. Chem. Soc. Dalton Trans. 21 2233 2236.

  34. 34.

    Godinho, K. G., Walsh, A. & Watson, G. W. Energetic and electronic structure analysis of intrinsic defects in SnO2. J. Phys. Chem. C 113, 439–448 (2009).

    Google Scholar 

  35. 35.

    Arularasu, M. V. et al. Structural, optical, morphological and microbial studies on SnO2 nanoparticles prepared by co-precipitation method. J. Nanosci. Nanotechnol. 18, 3511–3517 (2018).

    Google Scholar 

  36. 36.

    Zhou, W., Liu, Y., Yang, Y. & Wu, P. Band gap engineering of SnO2 by epitaxial strain: experimental and theoretical investigations. J. Phys. Chem. C 118, 6448–6453 (2014).

    Google Scholar 

  37. 37.

    Normura, K., Kamiya, T. & Hosono, H. Ambipolar oxide thin‐film transistor. Adv. Mater. 23, 3431–3434 (2011).

    Google Scholar 

  38. 38.

    Togo, A., Oba, F., Tanaka, I. & Tatsumi, K. First-principles calculations of native defects in tin monoxide. Phys. Rev. B 74, 195128 (2006).

    Google Scholar 

  39. 39.

    Wang, Z., Nayak, P. K., Caraveo-Frescas, J. A. & Alshareef, H. N. Recent developments in p-type oxide semiconductor materials and devices. Adv. Mater. 28, 3831–3892 (2016).

    Google Scholar 

  40. 40.

    Varley, J. B., Schleife, A., Janotti, A. & Van de Walle, C. G. Ambipolar doping in SnO. Appl. Phys. Lett. 103, 082118 (2013).

    Google Scholar 

  41. 41.

    Ha, V.-A., Ricci, F., Rignanese, G.-M. & Hautier, G. Structural design principles for low hole effective mass s-orbital-based p-type oxides. J. Mater. Chem. C 5, 5772–5779 (2017).

    Google Scholar 

  42. 42.

    Ogo, Y. et al. Tin monoxide as an s-orbital-based p-type oxide semiconductor: electronic structures and TFT application. Phys. Status Solidi A 206, 2187–2191 (2009).

    Google Scholar 

  43. 43.

    Zheng, X. et al. Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations. Nat. Energy 2, 17102 (2017).

    Google Scholar 

  44. 44.

    Li, C.-Z. et al. Doping of fullerenes via anion-induced electron transfer and its implication for surfactant facilitated high performance polymer solar cells. Adv. Mater. 25, 4425–4430 (2013).

    Google Scholar 

  45. 45.

    Sun, X. et al. Halide anion–fullerene π noncovalent interactions: n-doping and a halide anion migration mechanism in p–i–n perovskite solar cells. J. Mater. Chem. A 5, 20720–20728 (2017).

    Google Scholar 

  46. 46.

    Bai, Y. et al. Enhancing stability and efficiency of perovskite solar cells with crosslinkable silane-functionalized and doped fullerene. Nat. Commun. 7, 12806 (2016).

    Google Scholar 

  47. 47.

    Bush, K. A. et al. Compositional engineering for efficient wide band gap perovskites with improved stability to photoinduced phase segregation. ACS Energy Lett. 3, 428–435 (2018).

    Google Scholar 

  48. 48.

    Chen, S. et al. Exploring the stability of novel wide bandgap perovskites by a robot based high throughput approach. Adv. Energy Mater. 8, 1701543 (2018).

    Google Scholar 

  49. 49.

    Leijtens, T. et al. Tin–lead halide perovskites with improved thermal and air stability for efficient all-perovskite tandem solar cells. Sustain. Energy Fuels 2, 2450–2459 (2018).

    Google Scholar 

  50. 50.

    Han, Q. et al. Low-temperature processed inorganic hole transport layer for efficient and stable mixed Pb-Sn low-bandgap perovskite solar cells. Sci. Bull. 64, 1399–1401 (2019).

    Google Scholar 

  51. 51.

    Yang, Z. et al. Enhancing electron diffusion length in narrow-bandgap perovskites for efficient monolithic perovskite tandem solar cells. Nat. Commun. 10, 4498 (2019).

    Google Scholar 

  52. 52.

    Wang, Q. et al. Qualifying composition dependent p and n self-doping in CH3NH3PbI3. Appl. Phys. Lett. 105, 163508 (2014).

    Google Scholar 

Download references


This material is based on work supported by the Office of Energy Efficiency and Renewable Energy (EERE) of the US Department of Energy under Solar Energy Technologies Office (SETO) agreement numbers DE-EE0006709 and DE-EE0008749, and by the Research Opportunities Initiative of the University of North Carolina System.

Author information




J.H. conceived the study. J.H. and Z. Yu designed the experiments. Z. Yu and Z. Yang fabricated the tandem devices and conducted the characterization. Z. Yang optimized the NBG perovskite solar cells. Z.N. studied the electronic structure and characterization of tin oxide. Z.N. and Y.S. performed the Hall effect measurement. B.C. measured the EQE spectra and took the SEM images. Y.L. and H.W. analysed the data. Z.J.Y. and Z.H. verified the JV curves of the tandem device by using their dual-lamp solar simulator. J.H. and Z. Yu wrote the paper, and all authors reviewed the paper.

Corresponding author

Correspondence to Jinsong Huang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Supplementary information

Supplementary Information

Supplementary Figs. 1–20 and Supplementary Tables 1–7.

Reporting Summary

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Yu, Z., Yang, Z., Ni, Z. et al. Simplified interconnection structure based on C60/SnO2-x for all-perovskite tandem solar cells. Nat Energy 5, 657–665 (2020).

Download citation


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