advances.sciencemag.org/cgi/content/full/2/1/e1501170/DC1

Supplementary Materials for

Efficient luminescent solar cells based on tailored mixed-cation

perovskites

Dongqin Bi, Wolfgang Tress, M. Ibrahim Dar, Peng Gao, Jingshan Luo, Clémentine Renevier,

Kurt Schenk, Antonio Abate, Fabrizio Giordano, Juan-Pablo Correa Baena, Jean-David Decoppet,

Shaik Mohammed Zakeeruddin, Mohammad Khaja Nazeeruddin, Michael Grätzel, Anders Hagfeldt

Published 1 January 2016, Sci. Adv. 2, e1501170 (2016)

DOI: 10.1126/sciadv.1501170

The PDF file includes:

Fig. S1. Independent certification from Newport Corporation confirming PCEs of

19.90% (backward scan) and 19.73% (forward scan) and a normalized

electroluminescence quantum efficiency.

Fig. S2. Photograph of two real devices (front view and back view) showing the

active area of the solar cell, the high reflectivity of the smooth gold electrode, and

the densely opaque optical appearance of the perovskite film.

Fig. S3. Histogram of solar cell efficiencies for 40 solar cells, with the optimized

PbI2/FAI = 1.05.

Fig. S4. Initial stability test of PSCs sealed using epoxy and stored in a desiccator

in the dark.

Fig. S5. Absorption spectra of perovskite films on m-TiO2/c-TiO2/FTO substrate

with varying 2PbI /FAIR measured in transmission.

Fig. S6. Top-view SEM images of perovskite films on ms-TiO2/c-TiO2/FTO with

varying PbI2/FAI ratios (0.85, 1, 1.05, 1.1, 1.16, 1.23, 1.37, and 1.54) in the

precursor solutions.

Fig. S7. XRD patterns of perovskite films on ms-TiO2/c-TiO2/FTO with varying

PbI2/FAI ratios (0.85, 1, 1.05, 1.1, 1.16, 1.23, 1.37, and 1.54) in the precursor

solutions.

Fig. S8. Normalized (001) peaks of PbI2 phase showing the variation in full

widths at half maximum with increasing ratios of PbI2/FAPbI3 fraction.

Fig. S9. Cross-sectional SEM images of perovskite films on ms-TiO2/c-TiO2/FTO

with varying PbI2/FAI ratios (1, 1.05, 1.1, 1.23, 1.37, and 1.54) in the precursor

solution.

Fig. S10. External electroluminescence quantum efficiency as a function of the

injection current for the device with PbI2/FAI = 1.16.

Fig. S11. Normalized PL spectra of perovskite films on ms-TiO2/bl-TiO2/FTO

with varying PbI2/FAI ratios (1, 1.05, 1.1, 1.23, 1.37, and 1.54) in the precursor

solution.

Fig. S12. PL decay of perovskite films on ms-TiO2/bl-TiO2/FTO with varying

PbI2/FAI ratios (1, 1.05, 1.1, 1.16, 1.23, 1.37, and 1.54) in the precursor solution.

Table S1. Photovoltaic parameters for PSCs measured using forward scan (from

JSC to VOC) and backward scan (from VOC to JSC) at different scanning speeds (B,

backward; F, forward).

Table S2. Photovoltaic parameters for the stability of PSCs measured under AM

1.5 G illumination (solar cells were sealed with epoxy and stored in a dessicator).

Table S3. Composition of perovskite composite film determined by Rietveld

refinement.

Fig. S1 Independent certification from Newport Corporation confirming PCEs of 19.90 % (backward

scan) and 19.73% (forward scan) and a normalized electroluminescence quantum efficiency.

Fig. S2 Photograph of two real devices (front view and back view) showing the active area of the solar

cell, the high reflectivity of the smooth gold electrode, and the densely opaque optical appearance of

the perovskite film.

Fig. S3 Histogram of solar cell efficiencies for 40 solar cells, with the optimized PbI2/FAI = 1.05.

Fig. S4 Initial stability test of PSCs sealed using epoxy and stored in a desiccator in the dark.

Table S1. Photovoltaic parameters for PSCs measured using forward scan (from

JSC to VOC) and backward scan (from VOC to JSC) at different scanning speeds (B,

backward; F, forward).

Table S2. Photovoltaic parameters for the stability of PSCs measured under AM

1.5 G illumination (solar cells were sealed with epoxy and stored in a dessicator).

Scanning speed

（mV/s)

Voc Jsc

(mA/cm2)

FF PCE (%)

B-10 1.14 23.5 0.73 20.1

F-10 1.13 23.5 0.74 20.2

B-62 1.14 23.6 0.73 20.0

F-62 1.14 23.6 0.73 20.0

B-500 1.14 23.6 0.73 20.0

F-500 1.14 23.5 0.73 20.0

B-5000 1.14 23.6 0.73 20.1

F-5000 1.14 23.6 0.73 20.1

Voc Jsc

(mA/cm2)

FF PCE (%)

initially 1.16 24.4 0.72 20.5

After 216 h 1.17 23.1 0.74 20.2

After 360 h 1.15 23.6 0.74 20.4

After 648 h 1.15 23.5 0.73 20.1

After 768 h 1.15 23.6 0.73 20.2

Fig. S5 Absorption spectra of perovskite films on m-TiO2/c-TiO2/FTO substrate with varying

2PbI /FAIR measured in transmission. This data was used to estimate the relative amount of

perovskite by analyzing the absorbance spectra in the range between 550 and 700 nm after

subtracting a background absorption due to the substrate. This wavelength range was chosen

because PbI2 and other FAPbI3 phases do not show absorption in this range. The stoichiometric

device, which showed the largest absorbance in that wavelength range, was used as reference.

Dividing the other spectra by this spectrum gave a ratio independent of wavelength which

corresponds in first approximation to the perovskite thickness if the absorption coefficient of the

perovskite does not change.

Fig. S6 Top-view SEM images of perovskite films on ms-TiO2/c-TiO2/FTO with varying PbI2/FAI

ratios (0.85, 1, 1.05, 1.1, 1.16, 1.23, 1.37, and 1.54) in the precursor solutions.

Fig. S7 XRD patterns of perovskite films on ms-TiO2/c-TiO2/FTO with varying PbI2/FAI ratios (0.85, 1,

1.05, 1.1, 1.16, 1.23, 1.37, and 1.54) in the precursor solutions.

Table S3. Composition of perovskite composite film determined by Rietveld

refinement.

Sample

Ratio

PbI2/FAI

Film composition (Wt %) FWHM (001)

PbI2 [°]

Mean

Grain

Size

[nm]

FWHM

(011)/(101)

FAPbI3 [°]

Mean

Grain

Size

[nm]

Ratio of

grain

size

(PbI2/FA

I)

PbI2 Perovskite

compositesa

0.85 0 - - - 0.128551 88

1.00 0.003 99.997 0.140791 78 0.190116 54 1.44

1.05 3.87 96.13 0.13274 84 0.103681 118 0.71

1.1 1.35 98.65 0.159155 67 0.09390 137 0.49

1.16 7.52 92.48 0.192263 53 0.087688 153 0.35

1.23 7.10 92.90 0.193431 53 0.08960 148 0.36

1.37 26.13 73.87 0.162225 65 0.093064 139 0.47

1.54 40.53 59.47 0.137282 80 0.105093 116 0.69

PbI2 100 0 0.120232 96 - -

a. It is very difficult to quantify the amount of bromide perovskite due to the formation of several

different phases so we use perovskite composites to denote the rest of phases.

Fig. S8 Normalized (001) peaks of PbI2 phase showing the variation in full widths at half maximum

with increasing ratios of PbI2/FAPbI3 fraction. Open circles and solid lines represent measured data and

fit results, respectively.

Fig. S9 Cross-sectional SEM images of perovskite films on ms-TiO2/c-TiO2/FTO with varying

PbI2/FAI ratios (1, 1.05, 1.1, 1.23, 1.37, and 1.54) in the precursor solution.

1.54 1.37

1.23 1.1

1.05 1.00

Fig. S10 External electroluminescence quantum efficiency as a function of the injection current for the

device with PbI2/FAI = 1.16. The black line indicates a slope of 1.

Fig. S11 Normalized PL spectra of perovskite films on ms-TiO2/bl-TiO2/FTO with varying PbI2/FAI

ratios (1, 1.05, 1.1, 1.23, 1.37, and 1.54) in the precursor solution. Excitation wavelength is 460 nm.

The bandgap hardly shifts for samples with moderate PbI2 excess.

Fig. S12 PL decay of perovskite films on ms-TiO2/bl-TiO2/FTO with varying PbI2/FAI ratios (1, 1.05,

1.1, 1.16, 1.23, 1.37, and 1.54) in the precursor solution. Pulsed source at 406 nm, and the samples

were excited from perovskite side. The data shown in the main paper is corrected by subtracting the

time-independent (in the time window below 2 µs) background signal.