Supporting Information

Highly stable and efficient solid state solar cells based on methylammonium lead bromide

(CH3NH3PbBr3) perovskite quantum dots

Sawanta S. Mali Chang Su Shim, Chang Kook Hong*

*Polymer Energy Materials Laboratory, School of Applied Chemical Engineering, Chonnam

National University, Gwangju, 500-757 (South Korea),

S1 Characterizations

The surface morphology of the prepared samples was recorded by a field emission

scanning electron microscope (FESEM; S-4700, Hitachi). Transmission electron microscopy

(TEM) micrographs, selected area electron diffraction (SAED) pattern and high-resolution

transmission electron microscopy (HRTEM) images were obtained by TECNAI F20 Philips

operated at 200 KV. The TEM sample was prepared by drop casting of ethanolic dispersion

of the sample onto a carbon coated Cu grid. X-ray diffraction (XRD) measurements were

carried out using a D/MAX Uitima IIIXRD spectrometer (Rigaku, Japan) with CuK line of

1.5410 Å. The elemental information regarding the deposited samples was analyzed using

an STEM and EDS analysis which is connected with TEM.

The cells were illuminated using a solar simulator at AM 1.5 G for 10 s, where the

light intensity was adjusted with an NREL-calibrated Si solar cell with a KG-5 filter to 1 sun

intensity (100 mW cm-2). The IPCE spectra were measured as a function of wavelength

from 300 to 1100 nm on the basis of a Spectral Products DK240 monochromator.

Photoluminescence measurements were carried out on a PL mapper (Accent Opt. Tech. UK,

Model:RPM 2000, 532nm ND-YAG laser excitation).

Figure S1 Plane view of STEM micrographs of CH3NH3PbBr3 decorated mp-TiO2 and EDS

mapping of each elements. The elements are mentioned as per respective colors. Carbon-

green, titanium-red, oxygen-cyan, lead-yellow, bromine-cyan.

Figure S2 TEM analysis of CH 3NH3PbBr3+mp-TiO2 composite having ~10nm CH3NH3PbBr3

particle size (a) TEM micrograph of the perovskite CH3NH3PbBr3 deposited on mp-TiO2

nanoparticles (b-c) Highly magnified TEM images of CH3NH3PbBr3 coated TiO2

nanoparticles at different magnification. (d) HRTEM image of CH3NH3PbBr3 +mpTiO2.

Figure S3 TEM analysis of CH 3NH3PbBr3+mp-TiO2 composite having ~7-6nm particle size

(a) TEM micrograph of the perovskite CH3NH3PbBr3 deposited on mp-TiO2 nanoparticles

(b-c) Highly magnified TEM images of CH3NH3PbBr3 coated TiO2 nanoparticles at different

magnification. Inset shows FFT analysis of single CH3NH3PbBr3 nanoparticle (d) HRTEM

image of CH3NH3PbBr3 +mpTiO2.

Figure S4 TEM analysis of CH 3NH3PbBr3+mp-TiO2 composite having ~5-4nm

CH3NH3PbBr3 particle size (a) TEM micrograph of the perovskite CH3NH3PbBr3 deposited

on mp-TiO2 nanoparticles (b-c) Highly magnified TEM images of CH3NH3PbBr3 coated TiO2

nanoparticles at different magnification. (d) HRTEM image of CH3NH3PbBr3 +mpTiO2.

Figure S5 Normalized photoluminescence spectra of MAPbBr 3 nanoparticles/quantum dots with different size.

550 600 650 700

Nor

mal

ized

PL

Wavelength (nm)

MAPbBr3 (~10nm)

MAPbBr3 (~7nm)

MAPbBr3 (~5nm)

MAPbBr3 (~3nm)

Figure S6 J-V curves of forward and reverse bias sweep and respective JV curves for spiro- MeOTAD using CH3NH3PbBr3 perovskite absorber layer with different size. J-V curves measured by forward and reverse scans with 10mV voltage steps and 50ms delay times under AM 1.5 G illumination.

0.0 0.2 0.4 0.6 0.8 1.00

2

4

6

8

10

12

FTO/Bl-TiO2/mp-TiO

2+MAPbBr

3/spiro-MeOTAD/Au

10nm Forwad 10nm Reversed 7nm Forward 7nm Reversed 5nm Forward 5nm Reversed

Curr

ent

den

sity

(m

A.c

m-2

)

Voltage (V)

Figure S7 J-V curves of forward and reverse bias sweep and respective JV curves for PTAA

using CH3NH3PbBr3 perovskite absorber layer with different size. J-V curves measured by

forward and reverse scans with 10mV voltage steps and 50ms delay times under AM 1.5 G

illumination.

0.0 0.2 0.4 0.6 0.8 1.0 1.20

2

4

6

8

10

12

Curr

ent

den

sity

(mA

cm-2

)

Voltage (V)

10nm Forward 10 reversed 7nm Forward 7nm Reversed 5 nm Forward 5nm Revesred

FTO/Bl-TiO2/mp-TiO

2+MAPbBr

3/PTAA/Au

Figure S8 Cross-sectional field emission scanning electron microscopic images of FTO/Bl-

TiO2/mp-TiO2+MAPbBr3/HTM/Au. (a-d) cross sectional images of PTAA based devices (e-f)

spiro-MeOTAD based perovskite devices. The mp-TiO2 layer has been deposited at different

spin coating speed. (a) 2500, (b) 3000, (c) 4000, (d) 5000, (e) 3000 (f) 4000rpm. Figure (e)

(e) and (f) show spiro-MeOTAD HTM based devices. Figure (e) shows ~80nm Au contact.

Figure S9 Average solar cell efficiencies were obtained from different MAPbBr 3

nanoparticles/quantum dots with different HTM materials.

2 4 6 8 103

4

5

6

7

8 spiro-MeOTAD PTAA

MAPbBr3 size (nm)

Effi

cien

cy fo

r sp

iro-

MeO

TA

D

4

5

6

7

8

9

10

Efficiency for P

TA

A

Table S1: Solar cell properties of MAPbBr 3 based perovskite solar cells having different

size. Device configuration FTO/Bl-TiO 2/mp-TiO2/CH3NH3PbBr3/spiro-MeOTAD/Au

HTM Particle

size

Scan

direction

VOC

(V)JSC

(mAcm -2 ) FF

( ) Average

Spiro-MeOTAD

~10nm Forward 0.839 8.37 0.43 3.02 3.47

Reverse 0.888 8.15 0.54 3.91

Spiro-MeOTAD

~7-8nm Forward 0.904 9.11 0.49 4.04 4.13

Reverse 0.873 8.97 0.54 4.22

Spiro-MeOTAD

~5-7nm Forward 0.862 10.06 0.46 4.45 4.5

Reverse 0.894 9.79 0.52 4.55

Table S2: Solar cell properties of MAPbBr 3 based perovskite solar cells having different

size. Device configuration FTO/Bl-TiO 2/mp-TiO2/CH3NH3PbBr3/PTAA/Au

HTM Particle

size

Scan

direction

VOC

(V)JSC

(mAcm -2 ) FF

( ) Average

PTAA ~10nm Forward 1.071 8.10 0.42 3.64 4.02

Reverse 1.069 8.41 0.49 4.40

PTAA ~7-8nm Forward 1.043 09.21 0.52 4.99 5.36

Reverse 1.047 09.44 0.58 5.73

PTAA ~5-7nm Forward 1.032 10.62 0.53 5.81 6.73

Reverse 1.082 10.85 0.59 6.93