Supplementary Information

Low-Temperature Solution-Processed Li-Doped SnO2 as an

Effective Electron Transporting Layer for High-Performance

Flexible and Wearable Perovskite Solar Cells

Minwoo Park1,2

, Jae-Yup Kim1, Hae Jung Son1, Chul-Ho Lee3, Seung Soon Jang4, and Min Jae

Ko1,3

1Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST),

Seoul 02792, Korea2Department of Chemical and Biological Engineering, Sookmyung Women’s University, Seoul

04310, Korea3KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul

02841, Korea4Computational NanoBio Technology Laboratory, School of Materials Science and

Engineering, Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332‐0245, USA

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Figure S1. (A) X-ray diffraction (XRD) of CH3NH3PbI3 thin film. Inset shows the photograph of

the as-coated perovskite on FTO/Li:SnO2. (B) SEM image of perovskite.

Figure S2. Steady-state current density of SnO2- and Li:SnO2-device at the maximum power

voltages (Vmax), Vmax = 0.789 V and 0.848 V for SnO2- and Li:SnO2-device, respectively.

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Figure S3. J-V curves and parameters of Li:SnO2-device for different annealing times (1 h and 2

h).

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Figure S4. XPS spectra of Li:SnO2 thin film. Sn-3d, O-1s, and Cl-2p spectra and atomic

percentage correspond to (A), (B), and (C), respectively.

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Figure S5. (A) Transmittance graph of FTO/SnO2 and FTO/Li:SnO2. (B) Tauc plots of SnO2 and

Li:SnO2. From the equation of αhν = B(hν-Eg)n ,where α is the absorption coefficient, B is the

proportionality constant, hν is the photon energy, and n is the constant (n = 0.5 for direct band

gap), band gap (Eg) was estimated to be 3.95 eV.

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Figure S6. AFM images of bare FTO (A), FTO/SnO2 (B), and FTO/Li:SnO2 (C).

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Figure S7. (A, B) AFM image and height profile of SnO2 on ITO/glass. (C, D) AFM image and

height profile of Li:SnO2 on ITO/glass.

Rs [Ω] Rtr [kΩ] Rrec [kΩ] Ctr [μF] Crec [μF]

SnO2 0.93 8.3 3.0 0.0128 0.0343Li:SnO2 0.91 6.5 6.8 0.0311 0.0192

Table S1. EIS parameters of the perovskite solar cells.

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Figure S8. (A) Schematic of device architecture of flexible and wearable perovskite solar cell.

(B) J-V curve and parameters of the device.

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