Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites


Perovskite solar cells are remarkably efficient; however, they are prone to degradation in water, oxygen and ultraviolet light. Cation engineering in 3D perovskite absorbers has led to reduced degradation. Alternatively, 2D Ruddlesden–Popper layered perovskites exhibit improved stability, but have not delivered efficient solar cells so far. Here, we introduce n-butylammonium cations into a mixed-cation lead mixed-halide FA0.83Cs0.17Pb(IyBr1−y)3 3D perovskite. We observe the formation of 2D perovskite platelets, interspersed between highly orientated 3D perovskite grains, which suppress non-radiative charge recombination. We investigate the relationship between thin-film composition, crystal alignment and device performance. Solar cells with an optimal butylammonium content exhibit average stabilized power conversion efficiency of 17.5 ± 1.3% with a 1.61-eV-bandgap perovskite and 15.8 ± 0.8% with a 1.72-eV-bandgap perovskite. The stability under simulated sunlight is also enhanced. Cells sustain 80% of their ‘post burn-in’ efficiency after 1,000 h in air, and close to 4,000 h when encapsulated.

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Figure 1: Morphology and crystal phases.
Figure 2: BA-enhanced 3D perovskite crystalline growth.
Figure 3: 2D–3D perovskite heterostructure.
Figure 4: Device performances of the BA/FA/Cs perovskite solar cells.
Figure 5: Device stability.


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This work was part-funded by EPSRC, UK, the European Union Seventh Framework Program under grant agreement number 604032 of the MESO project and AFOSR through project FA9550-15-1-0115. We thank A. A. Haghighirad for discussions concerning XRD analysis, and D. P. McMeekin for discussion concerning device fabrication and film composition analysis. We would also like to thank M. T. Klug and R. Xiang for helping with illustrations.

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H.J.S. and Z.W. conceived the project. Z.W. designed the experiments, and fabricated the devices and thin-film samples. Q.L. performed optical spectroscopy and EQE measurements and analysed the data. Z.W. and F.P.C. performed the XRD measurement and analysed the XRD data. N.S. performed SEM measurement and contributed to device fabrication. L.M.H. supervised the optical spectroscopy experiments. H.J.S. supervised the whole project. Z.W. wrote the first draft of the paper. All authors discussed the results and contributed to the writing of the paper.

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Correspondence to Henry J. Snaith.

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Wang, Z., Lin, Q., Chmiel, F. et al. Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites. Nat Energy 2, 17135 (2017). https://doi.org/10.1038/nenergy.2017.135

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