Blade-Coating of High Crystallinity Cesium-Formamidinium Perovskite Formulations

Up-scalable coating processes need to be developed to manufacture efficient and stable perovskite-based solar modules. In this work, we combine two Lewis base additives (N,N′-dimethylpropyleneurea and thiourea) to fabricate high-quality Cs0.15FA0.85PbI3 perovskite films by blade-coating on large areas. Selected-area electron diffraction patterns reveal a minimization of stacking faults in the α-FAPbI3 phase for this specific cesium-formamidinium composition in both spin-coated and blade-coated perovskite films, demonstrating its scaling potential. The underlying mechanism of the crystallization process and the specific role of thiourea are characterized by Fourier transform infrared spectroscopy and in situ optical absorption, showing clear interaction between thiourea and perovskite precursors and halved film-formation activation energy (from 114 to 49 kJ/mol), which contribute to the obtained specific morphology with the formation of large domain sizes on a short time scale. The blade-coated perovskite solar cells demonstrate a maximum efficiency of approximately 16.9% on an aperture area of 1 cm2.

Figure S6 shows typical heatmaps obtained from in situ optical measurements.Figure S7 shows typical absorption spectra at different times.For the kinetic analysis, the absorbance values are averaged between 600 and 800 nm and plotted versus time.

Figure S4 :
Figure S4 : (a, b) BF TEM micrographs for Cs0.15FA0.85PbI3perovskite blade-coated thin films (reference, target) indexed to a cubic superstructure FAPbI3 phase oriented near [011]C zone axis and the associated selected-area electron diffraction patterns (yellow circles indicate the position of the selected-area for SAED pattern acquisition).(c, d) BF TEM micrographs for Cs0.15FA0.85PbI3perovskite blade-coated thin films (reference, target) indexed to a cubic superstructure FAPbI3 phase oriented near [112]C zone axis and the associated selected-area electron diffraction patterns (yellow circles indicate the position of the selected-area for SAED pattern acquisition).

Figure S6 :
Figure S6: Heatmaps derived from in situ optical measurements for blade-coated Cs0.15FA0.85PbI3films (reference) annealed at 80°C (a) light intensity corrected with bright reference and dark reference (b) absorbance.

Figure S7 :
Figure S7: Absorbance spectra at different times during the annealing step for bladecoated Cs0.15FA0.85PbI3films (reference) annealed at 80°C.The legend indicates the values of time (in s).

Figure S10 :
Figure S10 : Spectra derived from in situ optical measurements for blade-coated Cs0.15FA0.85PbI3films (reference) annealed at different temperatures.The legend indicates the values of time (in s).

Figure S11 :
Figure S11 : Spectra derived from in situ optical measurements for blade-coated Cs0.15FA0.85PbI3films (target) annealed at different temperatures.The legend indicates the values of time (in s).

Figure S14 :
Figure S14 : Spectra derived from in situ optical measurements for spin-coated Cs0.15FA0.85PbI3films (reference) annealed at different temperatures.The legend indicates the values of time (in s).

Figure S15 :
Figure S15 : Spectra derived from in situ optical measurements for spin-coated Cs0.15FA0.85PbI3films (target) annealed at different temperatures.The legend indicates the values of time (in s).

Figure S17 :
Figure S17 : Plots constructed from equation (1) to extract the activation energy EA for spin-coated film (with TU additive in DMF/DMSO), slope of the line is 27 ± 3 kJ/mol.