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Supporting Information

Efficient, Hysteresis Free, Inverted Planar Flexible Perovskite Solar Cells via Perovskite Engineering and Stability in Cylindrical Encapsulation

Manish Pandey1,#,*, Gaurav Kapil2, Kazuhiko Sakamoto3, Daisuke Hirotani1, Muhammad Akmal Kamrudin1, Zhen Wang1, Kengo Hamada1, Daishiro Nomura3, Hyo-Gyoung Kang3, Hideaki Nagayoshi3, Masaki Nakamura4, Masahiro Hayashi5, Takatoshi Nomura5, Shuzi Hayase1,*

1Division of Green Electronics, Graduate School of LSSE, Kyushu Institute of Technology,2-4 Hibikino, Wakamatsu, Kitakyushu, 8080196, JapanEmail: manish.iitp12@gmail.com; hayase.syuzi859@mail.kyutech.jp

2Research Center for Advanced Science and Technology, The University of Tokyo4-6-1, Komaba, Tokyo,153-8904, Japan

3FUJICO CO. LTD., 4-31 Makiyamashinmachi, Tobata, kitakyushu, 804-0054, Japan

4Power System Department, Corporate R&D Division, USHIO.INC, 1194, Tosa, Besshomachi, Himeji, Hyogo, 671-0224 Japan

5CKD Corporation, 2-250, Ouji, Komaki, Aichi, 485-8551, Japan

# Present Address: Laboratory for Organic Electronics, Division of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan

*Corresponding Authormanish.iitp12@gmail.comhayase.syuzi859@mail.kyutech.jp

Electronic Supplementary Material (ESI) for Sustainable Energy & Fuels.This journal is © The Royal Society of Chemistry 2019

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0.0 0.2 0.4 0.6 0.80

4

8

12

16

20

J (m

A/cm

2 )

Voltage (V)

0 0.1 0.2 0.3

FAXMA1-XPbI3X

(a)

(b)

FAXMA1-XPbI3

6

8

10

12

14

PCE

(%)

0 0.1 0.2 0.312

14

16

18

20

X

Jsc

(mA/

cm2 )

0.70

0.75

0.80

0.85

0.90

0.95

1.00

Voc

(V)

0 0.1 0.2 0.30.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

FF

X

FAXMA1-XPbI3

FAXMA1-XPbI3 FAXMA1-XPbI3

(c)

(d)

(e)

(f)

Nor

mal

ized

PL

FAXMA1-XPbI3

X

Wavelength (nm)

0 0.1 0.2 0.3

700 750 800 850 900

0

0.5

1

Fig. S1 (a) Normalized steady-state photoluminescence films FAXMA1-XPbI3 by 1-step method using toluene as anti-solvents. (b) JV characteristics and (c-f) box plot of the electrical parameters of flexible PSCs prepared using FAXMA1-XPbI3 through 1-step deposition method using toluene as anti-solvents.

0 50 100 150 200

1

10

100

1000

PL In

tens

ity (a

. u.)

Time (ns)

0 0.2 0.3

FAXMA1-XPbI3X

4.5 5.0 5.5 6.0 6.5 7.0

0.00

0.01

0.02

0.03

0.04

Yiel

d 1/

3 (a

. u.)

Energy (eV)

X = 0 X = 0.1 X = 0.2 X = 0.3

(a)

(b) (c)

Fig. S2 IPCE spectra (a), Time-resolved PL decay (b) and photoelectron yield spectroscopy (c) of FAXMA1-XPbI3 perovskite films.

S3

10 12 14 16 40 42 44 46 48 50

FA0.2MA0.8 PbI3

FA0.2MA0.8 PbI3 + 56 mM Pb(SCN)2

PbI 2

Inte

nsity

(a. u

.)

2

110

Fig. S3 X-ray diffraction pattern of the FA0.2MA0.8PbI3 perovskite with and without Pb(SCN)2 additives. The diffraction pattern from 18 to 40 is intensely removed where intense peak originates from the PET substrates. Here 56 mM refers to 3 wt% of Pb(SCN)2.

8

10

12

14

PCE

(%)

0 3 4.5 6

14

16

18

20

Jsc (

mA/

cm2 )

Pb(SCN)2 conentration (wt%)

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

Voc (

V)

0 3 4.5 6

0.6

0.7

0.8

0.9

FF

Pb(SCN)2 conentration (wt%)

Fig. S4 Box-plot for electrical parameters flexible PSCs fabricated with FA0.2MA0.8PbI3 with varying Pb(SCN)2 concentration by 1-step method using toluene as anti-solvents.

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700 750 800 850 900

Wavelength (nm)

undoped 3 wt% 6 wt%

PL In

tensit

y (a

. u.)

0 100 200 300 400 500

1

10

100

1000

PL In

tensit

y (a

. u.)

Time (ns)

undoped 3 wt% 6 wt%

(a) (b)

Fig. S5 Photoluminescence response of FA0.2MA0.8PbI3 with varying conc. of Pb(SCN)2 additives fabricated dripped with toluene as anti-solvents. (a) steady-state PL and (b) time-resolved PL decay transients.

ETAC CBToluene2 m

2 m

2 m 2 m

2 m 2 m

Fig. S6 SEM image and AFM images of the perovskite film prepared with FA0.2MA0.8PbI3 having 3 wt% doped Pb(SCN)2 utilizing different anti-solvents. Scale length in each image is 2 m. Presence of pin-holes in films treated with TOL and CB were often seen as present in the SEM images and indicated by red-circles.

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8

10

12

14

16

18

PCE

(%)

ETAC Toluene CB8

12

16

20

24

Jsc

(mA/

cm2 )

0.80

0.85

0.90

0.95

1.00

Voc

(V)

ETAC Toluene CB

0.70

0.75

0.80

FF

Figure S7. Box-plot for electrical parameters flexible PSCs fabricated with FA0.2MA0.8PbI3 having varying 3 wt% of Pb(SCN)2 additives by various antisolvents ethyl acetate (ETAC), Toluene and chlorobenzene (CB).

ETAC Toluene CB0123456789

Rs (o

hm)

Figure S8. Box-plot for series resistance of flexible PSCs prepared with different antisolvents ethyl acetate (ETAC), Toluene and chlorobenzene (CB) with FA0.2MA0.8PbI3 having varying 3 wt% of Pb(SCN)2 additives.

The prepared devices were almost hysteresis free, calculated hysteric index was 0.0014 as

shown in Figure S9, Therefore confirmation of this behavior was also carried out by

measuring JV curves of the flexible devices taken under different scan rates of 10 to 1000

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mV/s, and almost no differences in the electrical characteristics were observed as shown in

Figure S10. These results suggest that the devices offered a well-balanced electron and hole

flux with less traps in the bulk perovskite as well as at the film interfaces. Such behavior can

be attributed to the various factors like grain size, film uniformity, absence of pin-hole in

ETAC dripped perovskite films.[1]

0.0 0.2 0.4 0.6 0.8 1.00

5

10

15

20

FF 0.79.18 78.82 PCE (%) 15.53 15.44

Jsc (mA/cm2) 21.41 21.42 Reverse

J (m

A/cm

2 )

Voltage (V)

Forward

Voc (V) 0.916 0.915

Figure S9. JV characteristics of flexible PSCs in forward and reverse direction scan prepared by FA0.2MA0.8PbI3 with 3 wt% of Pb(SCN)2 additives using ethyl acetate as anti-solvents.

0.0 0.2 0.4 0.6 0.8 1.00

5

10

15

20

J (m

A/cm

2 )

Voltage (V)

1000 mV/s 500 mV/s 200 mV/s 100 mV/s 50 mV/s 33.33 mV/s 25 mV/s 20 mV/s 10 mV/s

Figure S10. JV characteristics of flexible PSCs in forward direction at different scan rates prepared by FA0.2MA0.8PbI3 with 3 wt% of Pb(SCN)2 using ethyl acetate as anti-solvents.

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Figure S11. SEM image of the PET/ITO substrate after bending 500 times at a radius of 4mm. The blue arrow indicate the crack formation in the ITO electrode.

Table S1. Photovoltaic parameters of the flexible PSCs prepared with FAXMA1-XPbI3. Box plot of the devices is given in the Figure S1.

FAXMA1-XPbI3 JSC (mA/cm2) VOC (V) FF PCE (%)

X = 0 15.98 1.26 0.86 0.02 0.71 0.04 9.78 1.14

X = 0.1 15.66 1.66 0.87 0.03 0.76 0.01 10.34 0.76

X = 0.2 17.28 0.47 0.85 0.02 0.76 0.01 11.13 0.36

X = 0.3 16.98 0.62 0.84 0.057 0.70 0.04 8.97 0.69

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Table S2. Photovoltaic parameters of the FA0.2MA0.8PbI3 with varying amount of Pb(SCN)2.

Pb(SCN)2 conc. JSC (mA/cm2) VOC (V) FF PCE (%)

0 17.28 0.47 0.85 0.02 0.76 0.01 11.13 0.36

3 wt% 19.02 0.34 0.903 0.009 0.721 0.01 12.50408 0.38

4.5 wt% 17.89 0.76 0.895 0.012 0.73 0.03 11.79444 0.88

6 wt% 16.98 ± 0.62 0.908 ± 0.006 0.69 ± 0.02 10.79714 ± 0.43

Table S3: Comparison chart of recently reported efficiency in inverted flexible PSCs on flexible substrates.

Device Key Improvement Area (cm2) PCE Ref.

PET/ITO/PEDOT:PSS/PVK/P(NDI2DT-TTCN)-BCP/Au Use of polymeric ETM 0.09 12.5 % [1]

PET 57 um with embedded Ag mesh/ PEDOT:PSS/PVK/PCBM/Al

Low resistance with high transmittance substrate 0.1 14.2 % [2]

PEN/ITO/PEDOT:PSS/PVK/PCBM/Al Pin-hole free perovskite film 0.2 12.1 % [3]

c-ITO/metal NW-GFRHybrimer/ PEDOT:PSS/PVK/PCBM-BCP/Ag

indium tin oxide/metal nanowire composite

electrode- 14.15 % [4]

PET/ITO/NiOx/PVK/PCBM/Ag Use of NiOx as HTM 0.07 13.43 % [5]

PET/ITO/PhNa-1T/PCBM/Ag Use of new polymeric HTL 0.12 14.7 % [6]

PET/ITO/PEDOT:PSS/PEI.HI/PVK/PCBM-LiF/Ag - 0.096 13.8 % [7]

PET/ITO/PEDOT:PSS/PVK/C60/BCP/Ag

Perovskite Engineeringby optimizing

multication, Pb(SCN)2 additives and anti-

solvent

0.1 16.13% This Work

PEN/ITO/PTAA:F4-TCNQ/PVK/PCBM-BCP/Ag

Pseudohalide induced recrystallization of

perovskite0.09 17.04 [8]

PEN/ITO/Cu:NiO/PVK/C60-BCP/Ag Doping of NiO nanopaticle with Cu 0.08 17.31 [9]

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Table S4: Comparison of the bending test results of PSCs fabricated on PET/ITO and PEN/ITO substrates in recent years.

Flexible PSCs Architecture Radius (mm) Cycles PCE

retained Ref.

PEN/ITO/nTi-MOF/PCBM/PVK/Spiro-MeOTAD/Au 6 700 67.88 % [10]

PEN/ITO/SnO2/PVK/ Spiro-MeOTAD/Au 4 1000 ~80% [11]

PET/ITO/PEDOT:PSS/PVK/PCBM/Al 5 1000 ~35% [2]*

PET/ITO/PEDOT:PSS/PVK/C60/BCP/LiF/Al 4 1000 ~30% [12]*

PET/ITO/ ZnO/MAPbI3/PTAA/Au 4 100 ~80% [13]*

PEN/ITO/Au embedded-NiXO/PVK/PCBM-PEI/Ag 13.5 1000 ~93% [14]

PEN/ITO/C60-PAA-PVK/ Spiro-MeOTAD/Ag 10 600 83% [15]

PET/ITO/ZnO/PVK/ Spiro-MeOTAD/Au 12.5 400 40% [16]*

PEN/ITO/SnO2/PVK/ Spiro-MeOTAD/Au 8 800 80% [17]

PEN/ITO/TiO2-C60/PVK/ Spiro-MeOTAD/Ag 5 500 80% [18]

PET/Graphene/PEDOT:PSS/PVK/PCBM/Al 4 1000 20% [19]*

PET/ITO/PVK/P(NDI2DT-TTCN)-BCP/Au 10 500 74% [1]

MgF2/PET/ITO/Nb2O5/PVK/ Spiro-MeOTAD/Au 4(a) 5000 83% [20]

PET/ITO/PEDOT:PSS/PVK/C60-BCP/Ag 6 1000 92% This work

*These work has other electrodes in reference to ITO/PET, which shows better mechanical flexibility. (a)As claimed by the authors, they have used thin ITO (160 nm) electrodes, and this prevent the crack formation even when bent at radius of 4 mm, whereas commercially available ITO substrates had thickness of 400 nm which breaks even quicker due to high thickness at below 5mm.

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