Supplementary information for Understanding how excess lead iodide precursor improves halide perovskite solar cell performance Byung-wook Park et. al. 1
(a) (b) Film Thickness (nm) type Au ~ 80 PTAA 20-50 HaP 350-650 mp-tio2 80 200 d-tio2 40 60 FTO 600-660 Supplementary Figure 1 Side-by-side comparison of morphology (a) and atomic number (b) contrast of the device cross section. The characteristic thickness of the various layers was not affected by the presence of excess of PbI 2 in the deposition solution. 2
Supplementary Figure 2 Illustration of the fitting process to extract diffusion lengths. 3
EQE The number of samples a 25 b 25 20 20 Current density [ma/cm 2 ] 15 10 5 Revers Forward Revers Forward V oc (V) 1.05 1.03 J sc (ma/cm 2 ) 22.53 22.51 Fill factor (%) 76.22 46.77 Efficiency (%) 17.98 10.82 Control-HaP Current density [ma/cm 2 ] 15 10 5 Revers Forward Revers Forward V oc (V) 1.10 1.06 J sc (ma/cm 2 ) 23.14 22.42 Fill factor (%) 77.27 80.86 Efficiency (%) 19.63 19.17 w/-pbi 2 -HaP 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Potential [V] 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Potential [V] c 1.0 22.7 ma/cm 2 d 24 22 20 Control HaP w/-pbi 2 HaP 0.8 0.6 0.4 0.2 0.0 Control-HaP w/pbi 2 -HaP 22.2 ma/cm 2 350 400 450 500 550 600 650 700 750 800 850 Wavelength [nm] 18 16 14 12 10 8 6 4 2 0 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 Solar cell efficiency [%] Supplementary Figure 3. J-V curves for two representative HaP solar cells: (a) high hysteresis of J-V curves for control-hap, (b) low hysteresis of J-V curves for w/-pbi 2-HaP, (c) External quantum efficiency for cells made with control- and w/-pbi 2-HaP, and (d) Histogram of efficiencies for the cells fabricated with and without excess PbI2. Details on the PV cell fabrication are given in the main text. 4
Supplementary Figure 4 Side by side SE and EBIC images of cross-sections of cells with (a) Control-HaP and (b) w/pbi 2-HaP. The paths of the line profiles are marked with thin blue horizontal lines with arrows. The EBIC signal distributions are summarized in (c) and (d), for the two samples, using the results from the (a) and (b) images, respectively. 5
α[300] c α[311] c α[310] c α[220] c PbI 2 [003] t α[221] c FTO α[211] c FTO 3.1 α[210] c FTO δ[202] h α[200] c δ[112] h q z (Å -1 ) FTO α[111] c PbI 2 [002] t α[110] c 2.1 δ[101] h α[100] c δ[201] h PbI 2 [001] t δ[002] h δ[100] h δ[101] h 0.1-2.0-1.0 0.0 1.0 2.0 q xy (Å -1 ) Supplementary Figure 5. Miller indexes on 2D GIWAXS pattern for FA cation-substituted HaP film on FTO. 6
Ek = 11.6 kev Penetration Depth (nm) 100 10 1 0.0 0.1 0.2 0.3 0.4 0.5 Incidence angle, ( o ) Supplementary Figure 6. X-ray penetration depth to α-fapbi 3 film with x-ray incidence angles which were reported previously. 1 7
a Intensity [A. U.] -FAPbI 3 [100] PbI 2 [001] -FAPbI 3 [200] PbI 2 excess B A Control sample 10 15 20 25 30 35 X-ray diffrection angle [2 ] Supplementary Figure 7. Full (2θ range) XRD spectra for control-hap and w/-pbi 2-HaP films on FTO. (XRD measurements were done on a Rigaku D/MAX2500V/PC X-ray diffractometer at 40 kv, 200 ma with a Cu target.) 8
Intensity (a.u.) Intensity (a.u.) (a) Intensity (a.u.) α-fapbi 3 [100] c Control-HaP = 0.15 o = 0.2 o = 0.3 o (b) Intensity (a.u.) α-fapbi 3 [100] c w/-pbi 2 -HaP = 0.15 o = 0.2 o = 0.3 o 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 Azimuthal angle ( o ) Azimuthal angle ( o ) (c) α-fapbi 3 [100] c (d) α-fapbi 3 [100] c Substrate Substrate (e) PbI 2 [001] t Control-HaP = 0.15 o = 0.2 o = 0.3 o (f) PbI 2 [001] t w/-pbi 2 -HaP = 0.15 o = 0.2 o = 0.3 o 0 20 40 60 80 100 120 140 160 180 Azimuthal angle ( o ) 0 20 40 60 80 100 120 140 160 180 Azimuthal angle ( o ) Supplementary Figure 8. (a and b) One-dimensional (1D) patterns of α-hap [100]c at q xy of 1.0/Å, (c and d) schemes of texturing of crystal domains for control- and w/-pbi 2-HaP, and (e and f) 1D patterns of PbI 2 [001] t at q xy of 0.9/Å obtained from 2D-GIWAXS (Fig. 3). 9
Supplementary Figure 9. 2D GIWAXS images of as-prepared w/pbi 2-HaP film observed over 6 s to 40 s with heating up to 150 C. 10
(a) (b) 20 m 10 m (c) (d) 10 m 5 m (2) (1) Supplementary Figure 10. HR-TEM images (a) PbI 2 located 200 nm deep from HaP film surface for control-hap, (b) α-hap crystal orientation (blue: out-of-plane, red: in-plane), and (c and d) magnified images for the remnant PbI 2. 11
(a) Area β 200 m Area α (b) Area α (c) Area β TiO 2 A B 10 m 5 m HaP Supplementary Figure 11. HR-TEM images (a) low-magnified image for w/-pbi2-hap, (b) magnified image of area for δ-hap located between PbI 2 and α-hap phase, (c) magnified image of area for the observation of interface between TiO 2 and HaP in w/pbi 2 sample. 12
Control HaP precursor PbI2 excessed HaP precursor Supplementary Figure 12. Comparison of size and distribution of iodoplumbate complex measured by dynamic light scattering spectroscopy in control and w/pbi 2 precursor solution. 13
Supplementary References (1) Liu, J., Saw, Robert E., Kiang, Y.-H., Calculation of Effective Penetration Depth in X-Ray Diffraction for Pharmaceutical Solids, J. Pharm. Sci. 99, 3807 3814 (2010). 14