Figure S1: Contact angle of a) W-SnO2 on ITO without prior cleaning b) After cleaning with DI water c) B-SnO2 on ITO without prior cleaning d) After cleaning with DI wáter. -- Figure S2: SEM cross-section images of perovskite layer on a) B-SnO2 b) W-SnO2. -- Figure S3: Scanning electron microscopy -top view images a) ITO substrate; b) B-SnO2 on ITO ;C) W-SnO2 on ITO. -- Figure S4: Contact angle of perovskite solution on a) W-SnO2 without UV-ozone treatment b) W-SnO2 with UVozone treatment c) B-SnO2 without UV-ozone treatment d) B-SnO2 with UV-ozone treatment. -- Figure S5: Images of slot die coated SnO2 a) W-SnO2 b) B-SnO2 Corresponding power conversion efficiency v/s pump rate graph c) W-SnO2 based cell d) B-SnO2 based cell. -- Figure S6: X-Ray Photoelectron spectroscopy of SnO2 in comparison with bare ITO. -- Figure S7: X-Ray Photoelectron spectroscopy of B-SnO2 before and after soft touch. -- Figure S8: Best JV curves for different amounts of KF addition to SnO2 dispersion. -- Table S1 Parameters extracted from best JV Curves (Figure S8). -- Figure S9: Stability of solar cells over several weeks. Conditions: storage in dry nitrogen atmosphere (< 10% RH) in the dark. -- Figure S10: Statistical distribution of solar cell parameters (PCE, FF, Jsc and Voc) B-SnO2 (Black), W-SnO2(Red), WKF-SnO2(Green). -- Fig. S11 UPS spectra of valence band region (left) and secondary electron cutoff region (right) (a) WSnO2, (b) W-SnO2-KF (c) B-SnO2 energy. -- Fig. S12 Tauc plot a) B-SnO2 b) W-SnO2 c) WKF-SnO2. -- Table S2: UPS parameters for SnO2 films. -- Fig S13: Energy diagram respect to the vacuum energy (Evac) summarizing the energy level extracted UPS spectra, optical bandgap (Eg) (by UV-vis spectroscopy). -- Fig. S14 Nyquist plot of SnO2 measured at 0.80 V under the dark. -- Table S3. Series resistance and recombination resistance of Solar cells.

Peer reviewed