Supporting Information
Parameters influencing the deposition of methylammonium
lead halide iodide in hole conductor free perovskite-based solar cells
Bat-El Cohen, Shany Gamliel, Lioz Etgar*
Experimental
Material synthesis
CH3NH3I was synthesized as described previously1, by reacting 30 mL of methylamine
(40% in methanol, TCI) and 32.3 mL of hydroiodic acid (57 wt% in water, Aldrich) or
23.32 mL of hydrobromic acid (48wt% in water, Aldrich) in a 250 mL round bottom
flask at 0°C for 2 h with stirring. The precipitate was recovered by putting the solution on
a rotavap and carefully removing the solvents at 50°C. The yellowish raw product of
methylammonium iodide (CH3NH3I ) was washed with ethanol by stirring the mixture for
30 min. Then the mixture was filtered and washed three times with diethylether. After
filtration, the solid was collected and dried at 70°C in a vacuum oven for 24 h.
PbI2 was synthesized in the lab by reacting Pb(NO3)2, and KI with a ratio of 1 :2 in
distilled water at 100oC. The product was filtered and washed with distilled water; after
filtration the solid was collected and dried at 70° in a vacuum oven for 24 h.
Pb(NO3)2 + 2KI
PbI2+ 2K++ 2NO3-
Device fabrication
The substrate of the device was a SNO2:F (FTO) conducting glass (15Ω∙cm-1),
Pilkington). A blocking layer was deposited on the FTO glass using a solution of titanium
diisopropoxidebis(acetylacetonate) (TiDIP, 75% in isopropanol, Aldrich) in ethanol. The
TiDIP solution was spin coated and then annealed at 450°C for 35 min. The TiO2 solution
was spin coated and annealed at 500°C for 30 min subsequent to TiCl4 treatment for 30
min at 70°C and annealing at 500°C for 30 min.
The synthesis of the CH3NH3PbI3 on the TiO2 surface was carried out by a two-step
deposition technique.
First, PbI2 was dissolved in DMF and dropped onto the TiO2 film and spin coated at
different spin velocities, followed by annealing at 70°C for 30 min. In the second step, the
cell was dipped into methylammonium solution. Following the dipping step, the samples
were annealed at different temperatures for another 30 min.
During the dipping and the annealing, the CH3NH3PbI3was formed, indicated by the dark
brown color of the electrode. Finally, the back contact was deposited by evaporating 50
nm of gold under pressure of 5*10-6Torr. The active area was 0.09 cm2.
X-ray diffraction
X-ray powder diffraction measurements were performed in grazing incidence X-ray
diffraction (GIXRD) mode on the D8 advance diffractometer (Bruker AXS, Karlsruhe,
Germany) with a goniometer radius of 217.5 mm, a secondary graphite monochromator,
2° Soller slits and a 0.2 mm receiving slit. XRD patterns within the range 5 ° to 60°2θ
were recorded at room temperature using CuKa radiation (l ¼ 1.5418 °A) with the
following measurement conditions: tube voltage of 40 kV, tube current of 40 mA, stepscan mode with a step size of 0.02°2θ and counting time of 1 s–3 s per step. The value of
the grazing incidence angle was 2.5°.
Photovoltaic characterization
Photovoltaic measurements were made on a New Port system, composed of an Oriel I–V
test station using an Oriel Sol3A simulator. The solar simulator is class AAA for spectral
performance, uniformity of irradiance, and temporal stability. The solar simulator is
equipped with a 450 W xenon lamp. The output power is adjusted to match AM1.5 global
sunlight (100 mWcm-2). The spectral match classifications are IEC60904-9 2007, JIC C
8912, and ASTM E927-05. I–V curves were obtained by applying an external bias to the
cell and measuring the generated photocurrent with a Keithley model 2400 digital source
meter. The voltage step and delay time of photocurrent were 10 mV and 40 ms,
respectively. Oriel IQE-200 was used to determine the monochromatic incident photonto-electric current conversion efficiency. Under full computer control, light from a 150 W
xenon arc lamp was focused through a monochromator in the 300–1800 nm wavelength
range onto the photovoltaic cell under test. The monochromator was incremented through
the visible spectrum to generate the IPCE (λ) as defined by IPCE (λ) = 12,400 (Jsc/λ
φ),where λ is the wavelength, Jsc is the short-circuit photocurrent density (mA cm-2), and
φ is the incident radiative flux (mWcm-2). Photovoltaic performance was measured by
using a metal mask with an aperture area of 0.09 cm2.
Absorption measurements – the UV-vis absorption spectra were performed by using a
Jasco V-670 spectrophotometer.
Extra High Resolution Scanning Electron Microscopy (XHR-SEM) – the images
were obtained by using Magellan XHR SEM of FEI (Field Emission Instruments), The
Netherlands. The measurement conditions were 5 kV at various magnifications, as seen
on the data bar of the images.
Ultra High Resolution Scanning Electron Microscopy (UHR-SEM) – the images were
obtained by using Sirion UHR SEM of FEI (Field Emission Instruments), The
Netherlands. The measurement conditions were 5 kV at various magnifications, as seen
on the data bar of the images.
XPS data of the PbI2 synthesized in the lab and PbI2 purchased from Sigma-Aldrich.
Table S1:
Sample 1-PbI2- lab
Peak
Type
Position
FWHM
Raw Area
RSF
Atomic
Atomic
Mass
BE (eV)
(eV)
(cps eV)
Mass
Conc %
Conc %
I 3d
Reg
617.000
0.982
241777.3 10.343
126.904
43.02
O 1s
Reg
529.500
1.585
2560.3
0.780
15.999
6.11
N 1s
Reg
395.100
0.071
0.0
0.477
14.007
0.00
C 1s
Reg
282.200
1.382
4215.2
0.278
12.011
29.29
Pb 4f
Reg
136.100
0.773
92018.4
8.329
207.206
21.58
RSF
Atomic
Atomic
Mass
Conc %
52.59
0.94
0.00
3.39
43.08
Sample 3- PbI2- SIGMA
Peak
Type
Position
FWHM
Raw Area
BE (eV)
(eV)
(cps eV)
Mass
Conc %
I 3d
Reg
617.000
0.993
240803.8 10.343
126.904
42.97
O 1s
Reg
529.300
1.491
2003.4
0.780
15.999
4.79
N 1s
Reg
403.900
0.169
0.0
0.477
14.007
0.00
C 1s
Reg
282.200
1.359
4450.7
0.278
12.011
31.02
Pb 4f
Reg
136.100
0.774
90229.6
8.329
207.206
21.22
52.95
0.74
0.00
3.62
42.69
Figure S1: XPS spectra of the PbI2 synthesized in the lab and PbI2 purchased from
Sigma-Aldrich.
N 1s/7
x 10
I 3d/5
1
Bat_El_30Dec2013_1.vms
Bat_El_30Dec2013_3.vms
Name
I 3d 3/2 (I2; PbI2)
I 3d 1/2 (I2; PbI2)
630
Pos.
619.9
631.374
Bat_El_30Dec2013_1.vms
Bat_El_30Dec2013_3.vms
Area
%Area
140459.5 60.11
93546.0 39.89
I 3d 3/2 (I2; PbI2)
Area
%Area
139507.0 60.11
92911.7 39.89
I 3d 3/2 (I2; PbI2)
I 3d 1/2 (I2; PbI2)
620
610
590
580
x 10
14
570
4
Name
I 3d 3/2 (I2; PbI2)
I 3d 1/2 (I2; PbI2)
Pos.
619.9
631.372
12
I 3d 1/2 (I2; PbI2)
10
560
CPS
CPS
600
8
6
550
4
2
404
402
400
398
Binding Energy (eV)
396
394
630
620
Binding Energy (eV)
Pb 4f/9
x 10
3
Bat_El_30Dec2013_1.vms
Bat_El_30Dec2013_3.vms
70
Name
Pb 4f 7/2 (PbO; PbI2)
Pb 4f 5/2 (PbO; PbI2)
Pos.
139
143.855
Area
%Area
49269.9 57.19
49631.6
36952.5 42.81
37223.7
60
50
CPS
40
30
20
10
148
1
146
144
142
140
Binding Energy (eV)
138
136
134
Jeong-HyoekIm; Jaehoon Chung; Seung-Joo Kim; Nam-Gyu Park. Synthesis, structure,
and photovoltaic property of a nanocrystalline 2H perovskite-type novel sensitizer
(CH3CH2NH3)PbI3, Nanoscale Research Letters 2012, 7, 353.