Electrochromic properties of phenantrene centered EDOT polymers

Article abstract of DOI:10.1016/j.polymer.2017.07.035

A series of phenantrene centered donor-acceptor type electroactive 3,4-ethlenedioxythiophene (EDOT) monomers (EP-X) containing N, S and Se heteroatom on the bezophenantra-X-diazole acceptor unit have been synthesized by Stille coupling reaction. These monomers were electrochemically polymerized by potentiodynamic method to obtain electrochromic polymer films. Spectro-electrochemical properties were also investigated by UV-vis absorption connected with the cyclic voltammetry measurements. The polymer films exhibited a remarkable trend of visible color (yellow, orange, red) at the neutral state due to changing the central acceptor moiety. These polymer films have multielectrochromic properties by means of moderately changing the absorbance/transmittance at the visible regime upon applied positive potentials. The donor-acceptor interaction at the neutral state correlated by DFT calculations was also supported by the interesting trend in the colors of these polymers. Finally, the electrochromic performance of EP-X polymer films represented a high redox stability, reasonable contrast ratio, coloration efficiency and response times.

Full text of DOI:10.1016/j.polymer.2017.07.035

Accepted Manuscript
Electrochromic properties of phenantrene centered EDOT polymers
Betül Colak, Ahmet Büyükkoyuncu, Fatma Baycan Koyuncu, Sermet Koyuncu
PII:
S0032-3861(17)30702-4
10.1016/j.polymer.2017.07.035
JPOL 19847
DOI:
Reference:
To appear in: Polymer
Received Date: 3 May 2017
Revised Date: 7 July 2017
Accepted Date: 11 July 2017
Please cite this article as: Colak Betü, Büyükkoyuncu A, Koyuncu FB, Koyuncu S, Electrochromic
properties of phenantrene centered EDOT polymers, Polymer (2017), doi: 10.1016/
j.polymer.2017.07.035.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Graphical Abstract
Electrochromic properties of phenantrene centered EDOT polymers
Betül Colak, Ahmet Büyükkoyuncu, Fatma Baycan Koyuncu, Sermet Koyuncu
1

ACCEPTED MANUSCRIPT
Electrochromic properties of phenantrene centered EDOT polymers
a
b
b
a,b
Betül Colak , Ahmet Büyükkoyuncu , Fatma Baycan Koyuncu , Sermet Koyuncu
a
Department of Energy Resources and Management, Çanakkale Onsekiz Mart University, 17020
Çanakkale, Turkey
b
Department of Chemistry, Faculty of Arts and Sciences, Çanakkale Onsekiz Mart University,
1
7020 Çanakkale, Turkey
d
Department of Chemical Engineering, Çanakkale Onsekiz Mart University, Canakkale, Turkey
*
Corresponding author: Sermet Koyuncu
Fax: +90-286-2180541; Tel: +90-286-2180018; e-mail: skoyuncu@comu.edu.tr
1

ACCEPTED MANUSCRIPT
Abstract
A series of phenantrene centered donor-acceptor type electroactive 3,4-ethlenedioxythiophene
EDOT) monomers (EP-X) containing N, S and Se heteroatom on the bezophenantra-X-diazole
(
acceptor unit have been synthesized by Stille coupling reaction. These monomers were
electrochemically polymerized by potentiodynamic method to obtain electrochromic polymer films.
Spectro-electrochemical properties were also investigated by UV-vis absorption connected with the
cyclic voltammetry measurements. The polymer films exhibited a remarkable trend of visible color
(
yellow, orange, red) at the neutral state due to changing the central acceptor moiety. These polymer
films have multielectrochromic properties by means of moderately changing the
absobance/transmitance at the visible regime upon applied positive potentials. The donor-acceptor
interaction at the neutral state correlated by DFT calculations was also supported by the interesting
trend in the colors of these polymers. Finally, the electrochromic performance of EP-X polymer
films represented a high redox stability, reasonable contrast ratio, coloration efficiency and response
times.
Keywords: Electrochromic polymers, Phenantrene, EDOT
2

ACCEPTED MANUSCRIPT
1
. Introduction
Electrochromism is one of the important properties of the electroactive materials that can be defined
as reversible and visible change in color of such materials under an externally applied potential.[1]
Studies and interest on the electrochromic materials have been increasing due to their potential
applications, such as information storage,[2] electrochromic displays,[3] optical switch,[4] smart
windows[5, 6], antiglare mirrors [7, 8] and camouflage materials[9, 10]. Despite the fact that the
first studies about electrochromic materials started with the inorganic semiconductors (e.g. metal
oxide materials) [11, 12]. Recently organic semiconductors have been more popular than the
inorganic ones due to their some superior features such as low driving voltage, high coloration
efficiency and low cost [13]. The main advantage of organic materials in electrochromic technology
are simple and inexpensive in the solution processing thin film formation[14, 15]. Another
advantage is the observation of different colors in these materials between their redox steps under
applied potentials [16, 17]. Among organic electrochromic materials, conjugated polymers have
superior characteristics due to their excellent color efficiency[18], fast color change capacity[19],
observation of many colors in same material [20] and the ability to adjust band gap values by
modifying chemical structure of the material [21]. Although many studies are realized with
electrochromic polymers, their commercialization has not been widespread yet. Long term stability
is the main problem of the polymeric electrochromic materials like other polymers that use in the
such applications [22]. Planar structures like perylene [23, 24], phenantrene [25], xanthene[26] and
pyrene[27, 28] are good candidates to improve the stability of thin film based organic
electrochromic devices due to rigidity and strong π-stacking interactions on the film surface. These
type polymers were also used in the other optoelectronic applications such as organic field effect
transistors (OFETs)[29], organic light-emitting diodes (OLEDs)[30] and organic photovoltaic
devices (OPVs)[31].
3

ACCEPTED MANUSCRIPT
Poly(3,4-ethylenedioxithiophene) (PEDOT) and its derivatives are widely used in
electrochromic materials due to low oxidation potential and good film forming ability [32, 33].
PEDOT derivatives is the one of the most important member of the neutral state blue
electrochromic materials. Another important property of PEDOT derivatives is high transmissivity
at the oxidized state[34]. These properties provide that PEDOT and its derivatives are very
interesting members for electrochromic application to complete the RGB main color space [35, 36].
Furthermore, in order to complete CMYK color space, PEDOT based donor-acceptor polymers are
generally used in the literature[37].
Herein, a series of planar phenantra-X-diazole centered donor acceptor monomer with EDOT
moiety were synthesized. Furthermore, optical, electrochemical properties and also electrochromic
performance were compared according to differentiated acceptor center moieties. The stepwise red
shift was observed both absorbance and photoluminescence of the donor-acceptor monomers by
changing the acceptor ability. Because of this property, the neutral state color on the thin film
surface was varied from yellow to red. All polymer films have multielectrochromic behaviors in
order to intensify the new band in the visible regime upon applied positive potential. Cihaner et al.
was also synthesized EDOT-benzothiadiazole based donor acceptor polymer to investigate the
donor-acceptor interaction effect on the electrochromic performance [21]. In this work, the center
planarity of the donor-acceptor electrochromic polymers is expanded for the first time by using
phenantrene center unit instead of phenylene. Kinetic study reveals that all electrochromic EP-X
polymer films are very stable against the applied sequential potential between oxidized and reduced
state.
4

ACCEPTED MANUSCRIPT
2
2
. Experimental
.1. Materials
All chemicals supplied from Aldrich and TCI Chemical Co. were used without further purification.
Phenantrene centered EDOT electroactive monomers were prepared according to synthetic route on
the Scheme 1. Synthetic procedures of initial compounds, M1-4 were given in the Supporting
Information.
O
O
H N
NH2
HO
N
N
OH
2
b
a
M2
c
M1
X
X
X
N
N
N
N
N
N
S
S
e
d
I
I
O
O
O
O
M3-X (X: S, Se, N-C H )
6 13
M4-X (X: S, Se, N-C H )
6
13
X: N-C H ---EP-1
6
13
S-------------EP-2
Se-----------EP-3
a) NH OH.HCl,pyridine/ethyl alcohol, 130 C, 3 h; b) Pd/C,ethyl alcohol, 110 °C, 3 h; c) for M3-N---i)Acetic acid,
2
NaNO , ii) methanol,potassium tertbutoxide, 60 °C, 12 h; for M3-S: S Cl , DMF, 2 h, r.t.; for M3- Se: SeO , Ethyl
2
2
2
2
Alcohol, 80 °C, 2 h. d) NIS, H
2
SO
4
, r.t., 2 h; e) Pd(PPh
3
)
4
, Toluene, 110 °C, 5 h;
Scheme 1. Synthetic route to EP-X monomers
5

ACCEPTED MANUSCRIPT
2
.2. Synthesis of 5,10-bis(3,4-ethylenedioxythienyl)phenantro[9,10-c][1,2,5]-X-azole (EP-X)
monomers
M4-X (0.5 mmol), 2-(tri-n-butylstannyl)-3,4-ethylenedioxythiophene (0,7 g, 1.5 mmol) and 15 mL
toluene were added in a 100 ml flask and stirred under argon atmosphere, for 30 min. After adding
o
the Pd(PPh ) (5 mol %) as a catalyst, the reaction mixture was refluxed at 110 C for 24 h. Finally,
3
4
the reaction mixture was cooled and precipitated in 500 mL of ethanol. Column chromatography
[
silica gel, CHCl :Hexane (1:1)] was carried out for the final purification. The pure yellow product
3
o
(
EP-X) was obtained and then dried at 40 C in vacuum oven.
X
N
d
N
b
S
S
a
O
O
e
c
O
O
f
6
EP-X, X: -N-C H5, S, Se
1
EP-N; (yellow powder; 0,19 g; yield:37%); H-NMR (CDCl
3
): δ ppm, 6.04 (a,2H, Haa’); 8.03 (d,
2
H, H ’); 7.5 (d, 2H, H ’); 8.84 (d, 2H, H ’), 4,26 (t, H ’, 2H), 4.66 (t, 4H, -CH -); 2.44 (m, 8H, -
bb cc dd ee 2
CH -); 1.61 (m, 4H, -CH ); 1.25 (m, 8H, -C H -); 0.88 (t, 6H, -CH ).
2
2
2
4
3
1
EP-S; (yellow powder; 0,20 g; Yield:45%); H-NMR (CDCl ): δ ppm, 6.04 (d, 2H, H ’); 7.95 (d,
3
aa
2
H, Hbb’); 7.61 (d, 2H, Hcc’), 8.71(d, 2H, Hdd’), 4.25 (t, 2H, Hee’), 4.26 (t, 2H, Hff’).
1
EP-Se; (yellow powder; 0,25 g; Yield:52%); H-NMR (CDCl ): 6.04 (d,2H, H ’); 8.14 (d, 2H,
3
aa
H ’); 7.42 (d, 2H, H ’), 8.76 (d, 2H, H ’), 4.25 (t, 2H, H ’), 4.30 (t, 2H, H ’).
bb
cc
dd
ee
ff
6

ACCEPTED MANUSCRIPT
2
.3. Instrumentation
FT-IR spectra were measured by a Perkin Elmer FT-IR Spectrum Two by using an ATR attachment
-1
1
(
4000–650 cm ). H-NMR (Bruker Avance DPX-400) data were recorded at 25 °C by using TMS
as internal standard and CHCl -d as solvent. CH Instruments 617D electrochemical workstation was
3
used in the cyclic voltammetry and chronoamperometry measurements. The electrochemical cell
2
consists of platinum disk (0.02 cm ) as a working electrode (WE), a Pt wire as counter electrode
6 2 2
(CE), a Ag wire as reference electrode (RE) immersed in 0.1 M TBAPF in CH Cl as the
supporting electrolyte. All measurements were carried out under argon atmosphere. Oxidation and
reduction potential onsets of EP-X monomers and polymers calibrated to the ferrocene redox couple
o
E (Fc/Fc+) = +0.41 V were used for the calculation HOMO-LUMO energy levels, and the
potentials. Analytic Jena Speedcord S-600 diode-array spectrophotometer was used in the UV-Vis
g
absorption and spectro-electrochemical measurements. The optical band gap (E ) of EP-X
monomers and polymers were calculated from their absorption edges. The spectro-electrochemical
cell consist of a quartz cuvette, an Ag wire as RE, Pt wire counter electrode as CE and ITO/glass as
transparent WE. These measurements were carried out in 0.1 M TBAPF as supporting electrolyte
6
in acetonitrile (ACN). Colorimetry measurements were carried out by using the same
spectrophotometer which consisted of a chromameter module (standard illuminator D65, field of
o
with 10 observer) with viewing geometry as recommended by CIE. According to the CIE color
measurements system, the color is obtained of three attributes; luminance (L), hue (a), and
saturation (b). Platinum cobalt DIN ISO 621, iodine DIN EN 1557, and Gardner DIN ISO 6430 are
the references of colorimetric measurement [38]. These parameters were measured for the neutral
and oxidized states of the polymers on the ITO/glass surface. To investigate surface morphology of
7

ACCEPTED MANUSCRIPT
the EP-X polymer films, a Nanosurf Naio-AFM were used at room temperature and ambient
condition., the non-contact mode was used in this system to obtain phase and topographic images.
The system was covered by acoustic chamber to avoid electromagnetic noises.
2
.4. Electrochemical polymerization of EP-X monomers
Electrochemical polymerization of EP-X monomers were carried out by using potentiodynamic
method. During the electrochemicaly coating process, the peak currents intensified after each cycle
between the redox potentials of the EP-X monomers. Finally, prepared polymer films on the
ITO/glass surface were rinsed with ACN to remove the electrolyte salts.
Fig. 1. Repeated potential scans of EP-X monomers (a: EP-N; b: EP-S; c: EP-Se) in 0.1 M TBAHF
6
in CH Cl , scan rate 100 mV/s.
2
2
8

ACCEPTED MANUSCRIPT
3
3
. Results and discussion
.1. Synthesis and Characterization
Electroactive EP-X monomers were synthesized in 5 steps (Scheme 1). First, 9,10-N,N'-
dihydroxyphenanthrene-9,10-diimine (M1) was prepared by the condensation reaction between
hydroxylamine hydrochloride and Phenantroquinone in ethanol-pyridine mixture. This compound
was reduced to its diamine derivative by using Pd/C as reducing agent in ethanol. Then, five
membered ring closing reactions were performed by using S, Se and N-hegzyl based reagents.
After that, synthesized phenantra-X-diazole compounds was iodinated by using N-iodosuccinimide.
Finaly, synthesis of EP-X electroactive monomers were achieved by Stille-coupling reaction
between Tributyl(2,3-dihydrothieno[3,4][1,4]dioxin-5-yl)stannane and diiodo-phenantra-X-dizole
compounds in presence of Pd(PPh ) as a catalyst. Then, chemical structure of initial compounds
3
4
1
and EP-X monomers were clarified by H NMR.
3
.2. Optical properties
The optical characterization of EP-X monomers were carried out by using UV-Vis absorption and
fluorescence spectroscopy techniques. Absorption spectra of EP-X monomers represented a
characteristic peak at λmax = 350 nm attributed to π-π* transition of the conjugated system (Fig. 2a).
Weak charge transfer bands occurred at 375-450 nm, due to the basic electronic interaction between
EDOT donor and the phenantra-X-diazole-acceptor moieties. The reason for the weak charge
transfer bands was partially blocked the intramolecular electron localization of the phenanthrene
moiety and hindered the charge transfer from the EDOT donor unit to the phenantra-X-diazole
acceptor unit. On the other hand, as the acceptor character increased from EP-N to EP-Se, the
charge transfer bands were shifted to the red region. Therefore, the optical band gap values
9

ACCEPTED MANUSCRIPT
calculated from the absorption onset were found to be 3.10 eV for EP-N, 2.75 eV for EP-S and 2.69
eV for EP-Se, respectively.
Similar effects were observed in UV-Vis absorption spectra of polymer films obtained by
electrochemical polymerization method (Fig. 2b). When compared to the EP-X monomers, a red
*
shift was observed in all spectra as a result of the increase of
π
-π
conjugation in the main chain
after polymerization process. The optical band gap values were calculated as 2.33 eV for poly(EP-
N), 1.92 eV for poly(EP-S) and 1.87 eV for poly(EP-Se) like monomeric structures.
On the other hand, the photoluminescence properties of EP-X electroactive molecules were
investigated by excitation at the maximum wavelength of the lowest energy absorption peak (Fig.
2
c). Like the absorption bands, the photoluminescence of EP-X linearly red shifted due to the
exchange of heteroatoms on the center of the phenantrene connected to the EDOT donor moiety.
The emission colors changed as blue, cyan and yellow upon varying the central acceptor unit.
1
0

ACCEPTED MANUSCRIPT
Figure 2. UV-vis absorption spectra of EP-X monomers in CH Cl (a), EP-X polymer films on
2
2
ITO/glass surface (b) and photoluminescence spectra of EP-X monomers in CH Cl .
2
2
3
.3. Electrochemical properties
The cyclic voltammograms of the EP-X monomers and corresponding polymers were measured in
the ACN electrolyte solution on the platinum disk WE surface (Fig 3 and 4). The EP-X polymers
were electrochemically coated onto the platinum disk electrode surface, while the monomers were
coated as drop casting process from the CH Cl solution. Due to the presence of the different
2
2
electron-acceptor phenantra-X-diazole moieties, the reduction peaks were shifted positively upon
changing the center atom from N-C H , S to Se, respectively. Obtained results clearly showed that
6
5
1
1

ACCEPTED MANUSCRIPT
the center heteroatom on the phenantra-X-diazole derivative was directly effective the
electrochemical reduction potentials for all molecules. According to these results, the LUMO levels
obtained from the reduction potential onsets were calculated as 2.84 eV for EP-N, 2.91 eV for EP-S
and 2.98 eV for EP-Se, respectively (Table 1). On the other hand, it was observed that the
oxidation potential did not change too much due to electron localization on the phenantrene center
containing triple condensed phenylene moieties. The HOMO levels was calculated from the
oxidation onsets was found as about 5.3 eV for all molecules.
6 2 2
Figure 3. Redox behavior of EP-N (a) EP-S (b) and EP-Se (c) in 0.1 M TBAPF /CH Cl electrolyte
solution at scan rate 100 mV/s, vs. Ag wire
1
2

ACCEPTED MANUSCRIPT
The same redox behaviors were observed for the EP-X polymers. Because of increasing
conjugation on the polymer backbone, the oxidation peak was observed as reversible and shifted
positively upon compared to the corresponding monomers. The HOMO level of poly(EP-N) was
observed higher than the other polymers. This might be happened due to having higher conjugation
degree of pol(EP-N) containing extra hexyl side chain. On the other hand, the band gap calculated
from the HOMO and LUMO levels was reduced from the 2.25 eV to 1.98 eV when changing the
heteroatom on the phenantra-X-diazole unit.
Figure 4. Redox behavior of EP-N (a) EP-S (b) and EP-Se (c) in 0.1 M TBAPF /ACN electrolyte
6
solution at scan rate 100 mV/s, vs. Ag wire
1
3

ACCEPTED MANUSCRIPT
Table 1. Optical and Electrochemical Values of EP-X monomers and corresponding polymers
Oxidation
Potantial
Reduction
Potantial
(V)
Optical
Band Gap
(eV)
Electrochem.
Band Gap
(eV)
HOMO LUMO
eV) (eV)
Molecule
(
(
V)
ox
red
EP-N
m,a
m,c
-5.29
-5.29
-2.84 3.1
2.45
E
E
E
E
E
= 1.13
= 1.05
= 1.30
= 1.07
= 1.11
E
E
E
E
E
= -1.58
= -1.74
= -1.34
= -1.26
= -1.78
ox
m,a
red
m1,c
EP-S
-2.91 2.75
2.38
ox
m,a
red
m,a
EP-Se
-5.31
-4.87
-5.03
-5.04
-2.98 2.69
-2.62 2.33
-2.99 1.92
-3.06 1.87
2.33
2.25
2.04
1.98
ox
m,c
red
m,c
ox
p,a
red
p,a
poly(EP-N)
poly(EP-S)
poly(EP-Se)
ox
p,c
red
p,c
E = 1.04
E = -1.55
ox
p,a
red
p,a
E
= 1.18
E
= -1.58
ox
p,c
red
p,c
E = 0.73
E = -1.56
ox
p,a
red
p,a
E
= 1.25
E
= -1.24
ox
red
p,c
p,c
E = 1.13
E = -1.13
3
.4. DFT calculations
Theoretical HOMO-LUMO charge distribution of the EP-X electroactive molecules were carried
out by using DFT calculations. The calculations were performed by Spartan10 program at the
parameters of B3LYP and 6-31 + G* basis set. It was clearly seen that all molecules were very flat
due to planar structure of the phenantrene center. The planar structures of the electroactive
molecules could positively affect the film forming property during the electrochemically coating
process on the WE surface. As a result of this approach, high-performance and highly stable
1
4

ACCEPTED MANUSCRIPT
polymer films could be obtained in the optoelectronic applications [25, 27, 39, 40]. According to
DFT calculations, the charges at HOMO orbital were localized on the EDOT-Phenanthene main
chain as electron donor moieties. On the other hand, the charges orbital were delocalized on the
electron-accepting phenantro-X-diazole subunit at LUMO. Due to weak acceptor property of the
triazole moiety, the charge on the EP-N could not much transfer to the acceptor unit when
compared to EP-S and EP-Se. The weak charge transfer band at UV-Vis absorption of EP-N also
supported this situation. Moreover, all theoretical calculated HOMO-LUMO orbitals were
compatible for the experimental values from the UV-Vis and CV measurements.
1
5

ACCEPTED MANUSCRIPT
Table 2. Molecular orbital diagrams and the HOMO-LUMO levels of EP-X electroactive
molecules.
Band Gap
Molecule
HOMO
LUMO
(eV)
3
.56 eV
EP-N
-4.98 eV
-1.42 eV
EP-S
3
.23 eV
-5.14 eV
-1.91 eV
EP-Se
3
.17 eV
-5.18 eV
-2.01 eV
3
.4. Surface properties
Surface characterization of electrochemically coated EP-X polymer films was performed by atomic
force microscopy (AFM). The thicknesses of EP-X polymer films coated under the same conditions
were arranged between 104 nm and 186 nm (Table 3). The roughness was very low according to
electrochemically coated polymer films in the literature [41, 42]. This was probably due to self-
1
6

ACCEPTED MANUSCRIPT
assembly behavior of the planar phenantrene center on the polymer repeating unit[25]. In addition,
EP-N polymer film roughness was partially higher than the other EP-X polymers due to consisting
of side alkyl chain on the triazole unit on the polymer backbone. On the other hand, EP-N polymer
film has smaller particles than that of other EP-X polymer films because of the long alkyl chain
partly prevent packing by creating a steric hindrance in the three dimensional plane among the
polymer chains. Therefore, EP-Se polymer film has large and non-uniform crystalline domains
when compared the other EP-X polymer films (Fig 5).
Figure 5. AFM images of a) poly(EP-N), b) poly(EP-S) and c) poly(EP-Se)films; i) height image,
ii) phase image, and iii) topography image.
1
7

ACCEPTED MANUSCRIPT
Table 3. Surface properties of EP-X polymer films obtained from AFM measurements
Polymer film
Poly(EP-N)
Poly(EP-S)
Poly(EP-Se)
Thickness (nm) Roughness(RMS)(nm)
Average particle diameter (nm)
174
142
146
9.08
6.76
8.31
124
316
188
3
.6. Electrochromic properties
Electrochromic properties of EP-X polymer films were investigated by spectro-electrochemical
measurements in 0.1M TBAPF -ACN electrolyte. The EP-N polymer film color was yellow
6
because of having a weak shoulder absorption band connected with the π-π transition band at the
visible regime until 500 nm. When scanned between its redox potentials (0-1.8V), the new band
was intensified the 550 nm and the yellow color (L*:97.7; a: -2.24; b: 24.9) of the film was
converted to purple (L*: 76.1; a: 11.2; b: -5.5). On the other hand, the same trend was observed for
the EP-S and EP-Se polymer films. As mentioned in the optical properties section, the neutral state
absorption band was bathochromically shifted upon changing the acceptor unit on the EP-X
polymer structure. For EP-S polymer film, the orange color of the film (L*:86.1; a: 14.3; b: 28.4)
was converted to dark purple (L*:71.8; a: 9.8; b: -9.9) when observed a new band centered at about
6
00 nm at the oxidized state (1.6V). Due to having phenantra-selenadiazole as a stronger acceptor
moiety, the sharp charge transfer absorption band at the neutral state was observed. When applied
positive potentials between 0-1.6V, the new band was seen at about 600 nm like EP-S polymer and
the red coloured polymer film at the neutral state (L*:74.6; a: 26.7; b: 13.3) turned into violet
(
L*:67.8; a: 13.7; b: -20.4). Consequently, all EP-X polymer films had multielectrochromic
behavior due to dramatically changing their absorption behavior at the visible regime when applied
positive potential.
1
8

ACCEPTED MANUSCRIPT
Figure 6. UV-Vis spectrum and the color changes during the applied potential of poly(EP-X) films on
6
ITO/glass surface in 0.1 M TBAPF /ACN.
The electrochromic performances of EP-X polymer films were determined by applying a
chronoamperometry technique (Fig. 7). When the polymer films were analyzed with the changes in
transmittance (increments or decrements of the absorption band with respect to time) while
switching the potential step wisely between the neutral and oxidized states with a residence time of
1
0 s. According to these measurements, it has been determined that all EP-X polymer film maintain
the optical activity of above 95% after 5000 cycle (Table 4, Fig 7 and Fig. S1-3). Thin film
morphology is an important issue for organic optoelectronic device performance [39]. AFM results
also revealed that EP-X polymer thin films had uniform structure and low roughness degree
1
9

ACCEPTED MANUSCRIPT
according to electrochemical coating process due to self-organization property of phenantrene
center by strong π-π interaction at the solid state. Cihaner et al synthesized a series of benzo-X-
diazole---EDOT based electroactive structures for electrochromic applications [21]. When our work
was compared to that work, blue shifts were detected at the neutral state absorption bands and also
colors after the planarity was increased on the electroactive monomer center by attached
phenantrene moiety instead of phenylene. In our previous paper, the planar center effect on the
electrochromic performance was also investigated [25]. It was concluded that the planar center
moiety on the electroactive structure had a great impact especially on the electrochemical also
electrochromic stability of the polymers. Finally, the coloration efficiency values calculated for the
2
-1
2
-1
EP-N polymers (214 cm C ) were found to be about three times higher than the EP-S (62 cm C ,
2
-1
and EP-Se (58 cm C ) (Table 4). These values were very low except for EP-N when compared to
the literature [21]. EP-N has an extra alky chain on the triazole acceptor center and the electrolyte
dopant ions can more move in and out of the space between polymer chains owing to steric
hindrance of the alkyl chain of the electrochromic material during redox switching.
2
0

ACCEPTED MANUSCRIPT
Figure 7. Electronic absorption spectra for poly(EP-N) at 545 nm (a), poly(EP-S) at 650 nm (b) and
poly(EP-Se) at 650 nm (c) films in anodic regime between their redox potentials in a monomer-free 0.1 M
TBAPF /ACN solution.
6
2
1

ACCEPTED MANUSCRIPT
Tablo 4. Electrochromic Parameters for EP-X polymer films
Optical
Optical
Optical
activity after
5000 cycles
(%)
contrast
change
Responce
Time
Coloration
Efficiency
(cm /C)
contrast
change
Molecule
2
wavelength
(s)
(
∆
T%)
(nm)
Oxidation
∆
T: 48%
2
.4 s
Reduction
.7 s
Oxidation
.8 s
Reduction
,7 s
Oxidation
.2 s
Reduction
.0 s
poly(EP-N)
poly(EP-S)
poly(EP-Se)
545
650
650
Tneut.: 95%
T : 47%
%97
%96
%98
214
62
oxi.
1
∆
T: % 18
1
Tneut.: %99
T : %81
oxi.
0
∆
T: % 17
1
Tneut.: %96
T
58
oxi.: %79
1
4
. Conclusion
Herein for the first time we reported a series of phenantrene centered donor acceptor electroactive
monomers substituted with two EDOT unit by Stile coupling reaction. Then EP-X monomers were
electrochemically polymerized onto transparent ITO/glass surface to give very stable
electrochromic polymer films against to applied potential. Optical and electrochemical properties of
EP-X monomers and corresponding polymers were greatly influenced by changing central
heteroatom on the phenantra-X-diazoleacceptor unit. Besides, AFM results revealed that the
polymer particles have uniform structure thus well-organized polymer films could be obtained
owing to self-organization property of the planar phenantrene centers. Multielectrochromic
behavior could be obtained by the changing the absorbance/transmittance at the visible regime upon
applied positive potentials. Moreover, it was concluded that the planar center moiety was greatly
affected on the electrochromic stability performance of the electroactive polymer films.
2
2

ACCEPTED MANUSCRIPT
Acknowledgements
We also gratefully acknowledge to Scientific and Technical Research Council of Turkey
TUBITAK, project #: 113Z581) for financial support.
(
References
1
2
.
.
Mortimer RJ
Kojima K and Terao M
Notes & Review Papers 2004;43(10):7058-7064.
Green M and Kang K Displays 1988;9(4):166-&.
Chandrasekhar P Journal of the Electrochemical Society 1988;135(8):C395-C395.
Svensson JSEM and Granqvist CG Solar Energy Materials 1985;12(6):391-402.
Granqvist CG Renewable Energy 1994;5(1-4):141-153.
Tajima K, Hotta H, Yamada Y, Okada M, and Yoshimura K
012;100(9).
Richardson TJ
Yu HT, Shao S, Yan LJ, Meng H, He YW, Yao C, Xu PP, Zhang XT, Hu WP, and Huang
Journal of Materials Chemistry C 2016;4(12):2269-2273.
Beaupre S, Breton AC, Dumas J, and Leclerc M Chemistry of Materials 2009;21(8):1504-
513.
.
Chemical Society Reviews 1997;26(3):147-156.
.
Japanese Journal of Applied Physics Part 1-Regular Papers Short
3
4
5
6
7
.
.
.
.
.
.
.
.
.
.
Applied Physics Letters
2
8
9
.
.
. Solid State Ionics 2003;165(1-4):305-308.
W
.
1
1
1
0.
1.
2.
.
1
Shay JL, Beni G, Dautremontsmith WC, and Schiavone LM. Journal of the Electrochemical
Society 1979;126(8):C338-C338.
Cantao MP, Lourenco A, Gorenstein A, Detorresi SIC, and Torresi RM
and Engineering B-Solid State Materials for Advanced Technology 1994;26(2-3):157-161.
Beaujuge PM and Reynolds JR Chemical Reviews 2010;110(1):268-320.
Witker D and Reynolds JR Macromolecules 2005;38(18):7636-7644.
Bulloch RH, Kerszulis JA, Dyer AL, and Reynolds JR Acs Applied Materials & Interfaces
015;7(3):1406-1412.
Sonmez G, Meng H, and Wudl F
Sonmez G, Shen CKF, Rubin Y, and Wudl F
004;43(12):1498-1502.
. Materials Science
1
1
1
3.
4.
5.
.
.
.
2
1
1
6.
7.
.
Chemistry of Materials 2004;16(4):574-580.
Angewandte Chemie-International Edition
.
2
2
3

ACCEPTED MANUSCRIPT
1
1
2
2
2
2
2
2
2
2
8.
9.
0.
1.
2.
3.
4.
5.
6.
7.
Wu CG, Lu MI, Chang SJ, and Wei CS
070.
Ikenoue Y, Tomozawa H, Saida Y, Kira M, and Yashima H
991;40(3):333-340.
Wei HY, Hsiao YS, Huang JH, Hsu CY, Chang FC, Chen PL, Ho KC, and Chu CW
. Advanced Functional Materials 2007;17(7):1063-
1
.
Synthetic Metals
1
.
Rsc
Advances 2012;2(11):4746-4753.
Icli M, Pamuk M, Algi F, Onal AM, and Cihaner A
.
Chemistry of Materials
2
010;22(13):4034-4044.
Hsiao SH, Wang HM, Guo WJ, and Sun CH
011;212(8):821-830.
Sefer E, Bilgili H, Gultekin B, Tonga M, and Koyuncu S
28.
.
Macromolecular Chemistry and Physics
2
.
Dyes and Pigments 2015;113:121-
1
Ma WT, Qin LQ, Gao Y, Zhang WQ, Xie ZQ, Yang B, Liu LL, and Ma YG
Communications 2016;52(93):13600-13603.
.
Chemical
Polymer
Doyranli C, Colak B, Lacinel G, Can M, Koyuncu FB, and Koyuncu S
017;108:423-431.
Olech K, Gutkowski R, Kuznetsov V, Roszak S, Soloducho J, and Schuhmann W
.
2
.
Chempluschem 2015;80(4):679-687.
Sefer E, Hacioglu SO, Tonga M, Toppare L, Cirpan A, and Koyuncu S
Chemistry and Physics 2015;216(8):829-836.
. Macromolecular
2
2
8.
9.
Liaw DJ, Wang KL, and Chang FC
Zhang HJ, Wang Y, Shao KZ, Liu YQ, Chen SY, Qiu WF, Sun XB, Qi T, Ma YQ, Yu G, Su
ZM, and Zhu DB Chemical Communications 2006(7):755-757.
Salunke JK, Wong FL, Feron K, Manzhos S, Lo MF, Shinde D, Patil A, Lee CS, Roy VAL,
Sonar P, and Wadgaonkar PP Journal of Materials Chemistry C 2016;4(5):1009-1018.
. Macromolecules 2007;40(10):3568-3574.
.
3
3
3
3
0.
1.
2.
3.
.
Alqurashy BA, Cartwright L, Iraqi A, Zhang YW, and Lidzey DG. Polymers for Advanced
Technologies 2017;28(2):193-200.
Wang F, Wilson MS, Rauh RD, Schottland P, Thompson BC, and Reynolds JR
Macromolecules 2000;33(6):2083-2091.
.
Heuer HW, Wehrmann R, and Kirchmeyer S
002;12(2):89-94.
. Advanced Functional Materials
2
2
4

ACCEPTED MANUSCRIPT
3
3
4.
5.
Amb CM, Beaujuge PM, and Reynolds JR
.
Advanced Materials 2010;22(6):724-+.
Durmus A, Gunbas GE, Camurlu P, and Toppare L
. Chemical Communications
2
007(31):3246-3248.
Karabiyik E, Sefer E, Koyuncu FB, Tonga M, Ozdemir E, and Koyuncu S
014;47(24):8578-8584.
Dyer AL, Thompson EJ, and Reynolds JR
011;3(6):1787-1795.
Thompson BC, Schottland P, Zong KW, and Reynolds JR
000;12(6):1563-1571.
Liu F, Gu Y, Shen XB, Ferdous S, Wang HW, and Russell TP
013;38(12):1990-2052.
Tang C, Liu F, Xia YJ, Lin J, Xie LH, Zhong GY, Fan QL, and Huang W
3
3
3
3
4
4
4
6.
7.
8.
9.
0.
1.
2.
. Macromolecules
2
.
Acs Applied Materials & Interfaces
2
.
Chemistry of Materials
2
.
Progress in Polymer Science
2
.
Organic
Electronics 2006;7(3):155-162.
Ming SL, Feng ZL, Mo DZ, Wang ZP, Lin KW, Lu BY, and Xu JK
.
Physical Chemistry
Chemical Physics 2016;18(7):5129-5138.
Carbas BB, Odabas S, Turksoy F, and Tanyeli C. Electrochimica Acta 2016;193:72-79.
2
5

ACCEPTED MANUSCRIPT
Highlights
We report a series of phenantrene centered donor−acceptor type electroactive
polymer for electrochromic applications
►
►
A remarkable trend of visible color (yellow, orange, red) at the neutral state can
be obtained by changing the central acceptor moiety
►
It is observed that planar center unit is greatly affected on the electrochromic
stability performance of the electroactive polymer films.