Abstract
Recent advances in the use of organic–inorganic hybrid perovskites for optoelectronics have been rapid, with reported power conversion efficiencies of up to 22 per cent for perovskite solar cells1,2,3,4,5,6,7,8,9. Improvements in stability have also enabled testing over a timescale of thousands of hours10,11,12,13,14. However, large-scale deployment of such cells will also require the ability to produce large-area, uniformly high-quality perovskite films. A key challenge is to overcome the substantial reduction in power conversion efficiency when a small device is scaled up: a reduction from over 20 per cent to about 10 per cent is found15,16,17,18,19,20,21 when a common aperture area of about 0.1 square centimetres is increased to more than 25 square centimetres. Here we report a new deposition route for methyl ammonium lead halide perovskite films that does not rely on use of a common solvent1,2,4,5,6,7,8,9,10,11,12,13,14,15 or vacuum3: rather, it relies on the rapid conversion of amine complex precursors to perovskite films, followed by a pressure application step. The deposited perovskite films were free of pin-holes and highly uniform. Importantly, the new deposition approach can be performed in air at low temperatures, facilitating fabrication of large-area perovskite devices. We reached a certified power conversion efficiency of 12.1 per cent with an aperture area of 36.1 square centimetres for a mesoporous TiO2-based perovskite solar module architecture.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (grant nos 11574199 and 11674219), the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, Natural Science Foundation of Shanghai (17ZR1414800). We thank B. Dai from Instrumental Analysis Center of SJTU and G. Lu from Shanghai Institute of Organic Chemistry for NMR measurements, and Y. Wu for discussions. M.G. thanks the European Research Council (ERC) for support of this work under a Proof of Concept project associated with his Mesolight Advanced Research Grant (ARF).
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L.H. and X.Y. designed and directed the study. H.C., F.Y. and W.T. conceived and performed the main experimental work. J.H., M.Y., Y.W., F.X. and E.B. contributed to the characterization. X.Y., H.C., F.Y. and W.T. analysed the data. X.Y., M.G. and L.H. wrote the manuscript. All authors reviewed the paper.
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Extended data figures and tables
Extended Data Figure 1 The appearance of CH3NH3X·mCH3NH2, PbX2·nCH3NH2 and the mixture of CH3NH3I·3CH3NH2 and PbI2·CH3NH2.
Vial diameter, 10 mm.
Extended Data Figure 2 NMR spectra of CH3NH3I and PbI2 individually and with interaction with CH3NH2.
Top, 1H NMR of CH3NH3I with and without CH3NH2, and bottom, 207Pb NMR of PbI2 and with or without CH3NH2, in different mixtures or in solution in DMSO.
Extended Data Figure 4 The effect of pressure on the thickness and the light absorbance of perovskite films.
a, The light absorbance spectra of perovskite films deposited at different pressures; the light absorption at 600 nm was chosen to calculate the film thickness. b, The light absorbance at 600 nm (red symbols and axis) and the film thickness (blue symbols and axis) as a function of pressure.
Extended Data Figure 5 Illustration of perovskite films deposited by the present pressure-assisted processing method and by the spin-coating method.
In both cases, 200 μl of precursor solution was used on a 64 cm2 substrate.
Extended Data Figure 6 The ultraviolet–visible light absorption spectra of 16 pieces of 2 cm × 2 cm perovskite films.
The films were made by cutting an 8 cm × 8 cm film into 16 pieces: the spectra of each piece was recorded individually. The perovskite film was deposited via the present pressure processing method.
Extended Data Figure 7 IPCE spectrum.
The IPCE (incident photon-to-current conversion efficiency) spectrum of a solar cell with a perovskite film deposited by the present pressure processing method (see Methods for details).
Extended Data Figure 8 Statistics of the device performance.
Shown are the efficiency of devices with different aperture area (a), precursor amount (b), pressure (c), temperature (d), and peeling speed (e). The measurement was carried out under AM 1.5G simulated solar light, 100 mW cm−2. All devices were made using the present pressure-processing method. 10 devices were measured for statistical analysis in each case. In the boxplots, the star represents the maximum and minimum values; the open square represents the mean value.
Extended Data Figure 9 Evolution of the photovoltaic stability of an encapsulated perovskite solar module fabricated by the present pressure-processing method.
The module (36.1 cm2) was aged under a 10 mW cm−2 UV-filtered simulated sunlight at 45 °C in ambient air and maintained at the maximum power point. The energy conversion efficiency was measured under simulated AM 1.5 solar light, 100 mW cm−2 intensity. The module retained 90% of the initial performance after 500 h.
Extended Data Figure 10 The performance of a perovskite solar module certified by a public test centre.
Red line, current–voltage curve; green line, power–voltage curve. ISC is the current value at short circuit condition; VOC is the voltage at open circuit condition; Pmax is the maximum power; Vpmax is the voltage at the point of Pmax; Ipmax is the current at the point of Pmax; F.F. is the fill factor; Eff(da) is the efficiency calculated with a light power that is defined by a designated aperture; DTemp. is the designed temperature; MTemp. is the measured temperature; DIrr. is the designed irradiation intensity; MIrr. is the measured irradiation intensity.
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Chen, H., Ye, F., Tang, W. et al. A solvent- and vacuum-free route to large-area perovskite films for efficient solar modules. Nature 550, 92–95 (2017). https://doi.org/10.1038/nature23877
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DOI: https://doi.org/10.1038/nature23877
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