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All-perovskite tandem solar cells with improved grain surface passivation


All-perovskite tandem solar cells hold the promise of surpassing the efficiency limits of single-junction solar cells1,2,3; however, until now, the best-performing all-perovskite tandem solar cells have exhibited lower certified efficiency than have single-junction perovskite solar cells4,5. A thick mixed Pb–Sn narrow-bandgap subcell is needed to achieve high photocurrent density in tandem solar cells6, yet this is challenging owing to the short carrier diffusion length within Pb–Sn perovskites. Here we develop ammonium-cation-passivated Pb–Sn perovskites with long diffusion lengths, enabling subcells that have an absorber thickness of approximately 1.2 μm. Molecular dynamics simulations indicate that widely used phenethylammonium cations are only partially adsorbed on the surface defective sites at perovskite crystallization temperatures. The passivator adsorption is predicted to be enhanced using 4-trifluoromethyl-phenylammonium (CF3-PA), which exhibits a stronger perovskite surface-passivator interaction than does phenethylammonium. By adding a small amount of CF3-PA into the precursor solution, we increase the carrier diffusion length within Pb–Sn perovskites twofold, to over 5 μm, and increase the efficiency of Pb–Sn perovskite solar cells to over 22%. We report a certified efficiency of 26.4% in all-perovskite tandem solar cells, which exceeds that of the best-performing single-junction perovskite solar cells. Encapsulated tandem devices retain more than 90% of their initial performance after 600 h of operation at the maximum power point under 1 Sun illumination in ambient conditions.

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Fig. 1: Interaction between passivator and Pb–Sn perovskite surface.
Fig. 2: PV performance of Pb–Sn perovskite solar cells.
Fig. 3: Characterization of mixed Pb–Sn perovskite films with passivating agents.
Fig. 4: PV performance and stability of all-perovskite tandem solar cells with CF3-PA additive.

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Data availability

The data that support the findings of this study are available from the corresponding authors on reasonable request.


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This work was financially supported by the National Key R&D Program of China (grant no. 2018YFB1500102), the National Natural Science Foundation of China (grant nos. 61974063 and 61921005), the Natural Science Foundation of Jiangsu Province (grant nos. BK20202008 and BK20190315), the Technology Innovation Fund of Nanjing University, Fundamental Research Funds for the Central Universities (grant nos. 0213/14380206 and 0205/14380252), the Frontiers Science Center for Critical Earth Material Cycling Fund (grant no. DLTD2109), the Program A for Outstanding PhD Candidate of Nanjing University, and the Program for Innovative Talents and Entrepreneur in Jiangsu. The work at the University of Toronto was supported by the US Department of the Navy, Office of Naval Research (grant no. N00014-20-1-2572). SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada. K.R.G., S.M.P. and H.R.A. acknowledge the US Department of Energy, Office of Basic Energy Sciences under grant no. DE-SC0018208 for supporting the photoelectron spectroscopy measurements.

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Authors and Affiliations



H.T. conceived and directed the overall project. R.L. and Y.W. fabricated all the devices and conducted the characterization. Jian X. carried out the DFT simulation. M.W. performed Tof-SIMS, PL and PL-decay characterization. Z.Q. and C.Z. performed the terahertz measurements and analysis. Z.L. and G.C. carried out the grazing-incidence wide-angle X-ray scattering measurements. J.W., Z.L., K.X., B.C., Jun X., J.Z. and L.L. carried out device fabrication and materials characterization. S.M.P., H.R.A. and K.R.G. performed angle-dependent XPS characterization and analysis. E.H.S. and H.T. supervised the project and assisted in data analysis. R.L., M.W., Jian X., E.H.S. and H.T. wrote the manuscript. All authors discussed the results and commented on the paper.

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Correspondence to Edward H. Sargent or Hairen Tan.

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Extended data figures and tables

Extended Data Fig. 1 Optical simulation of all-perovskite tandem solar cells.

The implied photocurrent density (Jsc) of tandems was calculated as function of wide-bandgap and narrow-bandgap perovskite layer thicknesses.

Extended Data Fig. 2 PCEs of mixed Pb-Sn perovskite solar cells with various concentrations of passivating agents.

a, PEA; b, PA; c, CF3-PA. The absorber layer thickness is ~1,200 nm.

Extended Data Fig. 3 Performance of control and CF3-PA mixed Pb-Sn perovskite solar cells with various absorber thicknesses.

For regular thinner Pb-Sn perovskite solar cells (thicknesses of 750 and 900 nm), the diffusion lengths are sufficiently long to ensure charge transport within devices. This agrees with the finding that no obvious improvement was observed in regular thinner devices after we added the CF3-PA passivating agent. The abrupt drop in performance at the thickness of 1.45 μm comes because the precursor solution fails to form high-quality films, a result of finite solubility of metal halides in DMF/DMSO solvent.

Extended Data Fig. 4 Performance of champion mixed Pb-Sn perovskite solar cells.

a, EQE spectra of champion control and CF3-PA mixed Pb-Sn solar cells. The EQE values of CF3-PA device are substantially higher than those of previous works at wavelengths above 800 nm, mainly due to the use of thicker absorber while maintaining sufficient carrier transport. It is noted that such a high Jsc value is obtained herein together with high Voc and FF even when using a 1,200 nm absorber. b, Reverse and forward J-V curves of the champion CF3-PA mixed Pb-Sn solar cell. c, The steady-state PCE of the champion CF3-PA device.

Extended Data Fig. 5 Characterization of control and CF3-PA mixed Pb-Sn perovskite films.

a–b, Cross-sectional SEM images of 1200-nm-thick (a) control and (b) CF3-PA mixed Pb-Sn perovskite solar cells. c, The F 1s XPS spectra of the control and CF3-PA perovskite films. d, TOF-SIMS spectra of mixed Pb-Sn perovskite film with CF3-PA additive. The additive is accumulated on the top perovskite surface and at the perovskite/HTL interface.

Extended Data Fig. 6 Schematic of angle-dependent XPS measurements.

a, Schematic of angle-dependent XPS measurements with dashed yellow lines indicating the relative photoelectron probing depth. Angles were defined as normal of the sample to detector. b–c, Angle-dependent XPS spectra of the Sn 3d at detector take-off angle θ = 0, 45, and 75° for (b) control and (c) CF3-PA perovskite films. Red peaks are fitted to Sn2+ and the blue peaks are fitted to Sn4+.

Extended Data Fig. 7 Photovoltaic performance of wide-bandgap perovskite solar cells.

a, Statistics of PV parameters among 34 devices. b, c, J-V and EQE curves of the best-performing device.

Extended Data Fig. 8 Photovoltaic performance of all-perovskite tandem solar cells.

a, The PCE histogram of all-perovskite tandem solar cells (96 devices) with 1,200-nm-thick NBG subcell. The devices were measured with a mask having aperture area of 0.049 cm2. b, Steady-state output of the champion all-perovskite tandem solar over 600 s. The device exhibited a stabilized PCE of 26.6%.

Extended Data Fig. 9 Photovoltaic performance of large-area all-perovskite tandem solar cells.

a, EQE spectra of large-area tandem solar cell. b, PCE distribution of 21 large-area tandem devices.

Extended Data Table 1 Photovoltaic parameters of champion WBG subcell, NBG subcell and all-perovskite tandem solar cell

Supplementary information

Supplementary Information

Supplementary Notes 1–5, Figs. 1–21, Tables 1–5 and References.

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Lin, R., Xu, J., Wei, M. et al. All-perovskite tandem solar cells with improved grain surface passivation. Nature 603, 73–78 (2022).

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