Gaining Further Insight into the Effects of Thermal Annealing and Solvent Vapor Annealing on Time

12 Pages·2017·1.21 MB·English

by  Jie Min

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.
This journal is © The Royal Society of Chemistry 2017
Gaining Further Insight into the Effects of Thermal Annealing and Solvent Vapor
Annealing on Time Morphological Development and Degradation in Small Molecule
Solar Cells
Jie Min1,2*，Nusret S. Güldal2, Jie Guo1, Chao Fang1, Xuechen Jiao3, Huawei Hu3, Thomas
Heumüller2, Harald Ade3, Christoph J. Brabec2,4
1The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
2Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander-
University Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany
3Department of Physics and Organic and Carbon Electronics Laboratory (ORaCEL), North
Carolina State University, Raleigh, North Carolina 27695, United States
4Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstraße 2a, 91058 Erlangen,
Germany
*E-mail: [email protected] (J. Min)
0
-2
2)
-m
c -4
A
m
( -6
y
t
si
n -8
e
d
nt -10
e
r WO
r
u
C -12 TA
SVA
-14
0.0 0.2 0.4 0.6 0.8 1.0
Voltage (V)
Figure S1. Current density-voltage (J-V) characteristics of the relevant cells evaluated under
illumination with a solar simulator.
Table S1. Photovoltaic parameters of DRCN5T:PC BM BHJ solar cells fabricated under
70
different processing conditions. Cells were tested in air without encapsulations, illumination
intensity was 100 mW cm-2.
Processing conditions V [mV] J [mA cm-2] FF [%] PCE [%]
oc sc max
WO 982 7.53 48.24 3.57
TA 932 12.27 58.81 6.73
SVA 952 12.58 55.45 6.64

0,4
WO
TA
SVA
0,3
)
u.
a.
(
e
c
n 0,2
ba
r
o
s
b
A 0,1
0,0
400 500 600 700 800
Wavelength (nm)
Figure S2. Absorption spectrum of films without any treatments and with TA and SVA
treatments, respectively.
WO RMS = 1.0 nm TA RMS = 0.8 nm SVA RMS = 1.4 nm
Figure S3. AFM images (5×5 μm2; 1×1 μm2) of DRCN5T:PC BM BHJ layers without and
70
with TA and SVA treatments.

WO
1011
TA
SVA
)
u.
(a. 1010
y
t
si
n
e
t
n
I
109
0.1 1
-1
Q vector [A ]
Figure S4. Circular 1D GIWAXS profiles of DRCN5T:PC BM films under various annealing
70
conditions. The curves are vertically shifted for better comparison about PC BM scattering
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peak around 1.3 Å-1.
60
WO
TA
21) 50 SVA
-0
1

; 40
u.
a.
2 ( 30
q
y
t
si 20
n
e
nt
I 10
0
0.01 0.1
q (nm-1)
Figure S5. Lorentz-corrected and thickness normalized circular RSoXS profiles of
DRCN5T:PC BM films with different processing conditions. All data were takend under 284.2
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Ev, which maximizes inter-domain scattering and eliminates fluorescence background.
(a) (b) (c)
WO TA
SVA
Figure S6. Multi-peak fitting results of films with various processing conditions, implemented
to all RSoXS profiles.
(a) (b) (c)
WO TA SVA
Figure S7. Quantitative comparison between RSoXS and AFM images. The power spectral
density (PSD) of AFM images is converted from FFT of the direct images, weighted by q2. The
low-q peak from 270 eV RSoXS originates from mass-thickness variation, while the high q
peak in 270 eV RSoXS correlated well with the dominant peak of 284.2 eV RSoXS. The PSD
of AFM phase images matche well with 284.2 eV RSoXS, indicating that the phase images
reflect the material contrast between donor-rich domains and acceptor-rich domains within the
bulk of the films. The AFM height images exhibit large discrepancy with RSoXS results due to
the fact that AFM height measurement is only sensitive the topography of films.
Figure S8. Schematic illustration of the experimental chamber for in situ measurements of thin
film drying from the side view; the horizontal purple line on the sample represents the X-ray;
the red line indicates the measurement sequence of PL and LS.
Figure S9. Schematic of fitting model used for the thickness calculation of swollen films.
A layer (d ) under a solvent vapor which is a good solvent for one or all components in the
total
layer would induce a swelling behavior. The vapor starts to be absorbed by the film surface,
and creates a ‘second’ layer (d ) on the dry film (d ). This solvent-soaked layer can
blend+solvent blend
be modelled with effective medium approximation (EMA).[1] Three assumptions were made for
the thickness calculations: (1) the effect of re-evaporation is omitted. (2) Constituent molecules
are randomly distributed and are smaller than the wavelength. (3) It is assumed that the EMA
layer has high fraction of solvent molecules. Hence, the fraction of solvent molecules in the
EMA layer is taken as 90 v% and kept at this value for all calculations. The film optical
constants were determined by NIKA software,[2] which is a calculation method based on the
reflection and transmission behavior of a flat layer. Since SVA has induced changes in
crystallinity (i.e. change in refractive index), 2 sets of film optical constants were used in the
EMA and d layer modelling: (1) optical constants from the film without any treatment and
blend
(2) optical constants from the film with SVA treatment. Hence, the optical constants were
changed accordingly for the thickness calculation when reflection spectrum of the layer has
indicated crystallinity changes. The optical constants for chloroform molecules used in EMA
layer were modelled with a Cauchy dispersion[3] due to their transparency.
0.30
(a)
Fit Spectrum
0.25 Reflectometry data
EMA
u.) 0.20
a.
Blend n ( 0.15
o
ecti 0.10
efl
SiO = 2 nm R
2 0.05
Si Wafer = 650 µm 0.00
400 500 600 700 800
Wavelength (nm)

0.30
(b)
Fit Spectrum
0.25 Reflectometry data
0.20
Blend (dry layer, 111 nm) n (a.u.)0.15
ectio0.10
SiO = 2 nm Refl
2 0.05
Si Wafer = 650 µm 0.00
400 500 600 700 800
Wavelength (nm)

(c) 0.30
Fit Spectrum
0.25 Reflectometry data
EMA (blend + 5%CF, 116 nm) a.u.) 0.20
n ( 0.15
o
ecti 0.10
efl
SiO = 2 nm R
2 0.05
Si Wafer = 650 µm 0.00
400 500 600 700 800
Wavelength (nm)
(d)
0.30
Fit Spectrum
0.25 Reflectometry data
EMA (blend + 10%CF, 122 nm) a.u.) 0.20
n (
o 0.15
cti
e
SiO = 2 nm Refl 0.10
2
0.05
Si Wafer = 650 µm
0.00
400 500 600 700 800
Wavelength (nm)
Figure S10. Schematic of four different fitting models, including (a) the bilayer model as
mentioned above, (b) the single model with respect to the film layer without any chloroform,
(c) the single model with respect to the completely swelled film layer with 5% chloroform after
60 seconds, and (d) the single model with respect to the completely swelled film layer with 10%
chloroform after 60 seconds. While the right column presents the relevant fits of the reflection
spectrums.
Here Figure S10a is the EMA model as mentioned in Figure S9. Absorption peak (right column)
fits much better as compared to the other three models. As shown in Figure S10b, optical
constants of the model without any chloroform in film layer does not fit to the measured
reflectometry data of SVA 60th second. Absorption peak is blue-shifted, while n and k data of
the dray layer do not fit to that of SVA treated layer. We also used another model, showing that
the DRCN5T:PC BM layer is swelled completely with 5% chloroform after 60 seconds SVA.
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Theoretically, a dry non-porous layer with 111 nm dry thickness would be 116 nm after soaking
5 vol.% chloroform. Further checking the corresponding graph shows that the absorption peak
fits good from the position, but the intensity is too different between fit spectrum and
reflectometry data (see Figure S10c). In addition, when the film layer is swelled completely
with 10 vol.% chloroform, the thicknesses of swelled layer changes from 111 nm to 122 nm
after soaking. Compared with the reflectometry data, the absorption peak from the fit starts to
red shift with this model (see Figure S10d). In short, we selected this bilayer model (Figure S9)
to analysis the in situ PL data, resulting from the better fitting curve as compared to the other
three models.

0 s
0,25
10 s
20 s
0,20 30 s n [%]
40 s o
%] 50 s ecti
n [ 0,15 60 s Refl
o
ti 120 s
c
e 0,10
efl 550 600 650 700
R
Wavelength [nm]
0,05
0,00
400 500 600 700 800
Wavelength [nm]
Figure S11. The reflection spectra of TA film are plotted from 0 seconds till 120 seconds. The
inset is a zoom to the wavelength range of 550-750 nm for a better clarity of the spectral
changes.
0,35
0 s
0,30 60 s
90 s
%]
0,25 100 s n [
n [%] 0,20 111258000 sss Reflectio
o
cti 0,15 221400 ss
e 600 650 700
fl
e 0,10 Wavelength [nm]
R
0,05
0,00
400 500 600 700 800
Wavelength [nm]
Figure S12. The reflection spectra of SVA film are plotted from 0 seconds till 240 seconds.
The inset is a zoom to the wavelength range of 575-725 nm for a better clarity of the spectral
changes.

30
WO
TA
SVA
) 20
u.
a.
3
0
1
*
(
s
s 10
a
M
0
0.0 0.2 0.4 0.6 0.8 1.0
t /t
max
Figure S13. SIMS ion yield as a function of sputtering time for (a) WO sample, (b) TA sample and
(c) SVA sample, the depth distribution of DRCN5T molecules is shown here. The blue dashed line
is an indicator for the bottom interface between active layer and cathode.
(a) (b)
104
104
103
103
102
2) 2)
m 102 m
A/ A/101
J ( J (
101 100
100 HEloelcet rOonnl yO Dnleyv Diceev i ceh = e = cm2cVm-21Vs--11s-1 10-1 Ele cHtorolen OOnnllyy DDeevviiccee   he == ccmm22VV--11ss--11
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7
Vin (V) Vin (V)
Figure S14. The dark J-V characteristics of devices with TA and SVA treatments, including
hole-only devices and electron-only devices, respectively. The inset mobility data are average
values of each sample within 6 devices.

(a) (b)
1.00 1.00
0.95 0.95
Voc Jsc
orm. 0.90 orm. 0.90
n n
0.85 0.85
TA TA
SVA SVA
0.80 0.80
0 100 200 300 400 500 0 100 200 300 400 500
Time (h) Time (h)

(c) (d)
1.00 1.00
0.95
0.95
0.90
FF CE
norm. 0.90 orm. P 00..8805
n
0.75
0.85
TA 0.70 TA
SVA SVA
0.80 0.65
0 100 200 300 400 500 0 100 200 300 400 500
Time (h) Time (h)
Figure S15. Changes of normalized (a) V , (b) J , (c) FF and (d) PCE losses over
oc sc
illumination time for TA and SVA treated solar cells.