Results in Physics 13 (2019) 102355
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Results in Physics
journal homepage: www.elsevier.com/locate/rinp
Synergistic effect of poly(3,4-ethylenedioxythiophene), reduced graphene
oxide and aluminium oxide) as counter electrode in dye-sensitized solar cell
Wan Nor Azwani Wan Khalita, Muhammad Norhaffis Mustafaa, Yusran Sulaimana,b,
a
b
T
⁎
Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Functional Devices Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
ARTICLE INFO
ABSTRACT
Keywords:
Dye-sensitized solar cell
Aluminium oxide
Reduced-graphene oxide
Poly(3,4-ethylenedioxythiophene)
A new counter electrode which makes use of reduced graphene oxide (rGO), poly (3,4-ethylenedioxythiophene)
(PEDOT) and aluminium oxide (Al2O3) was developed to enhance the performance of dye-sensitized solar cell
(DSSC) device in replacing platinum as a counter electrode. PEDOT/rGO-Al2O3 was fabricated through the
deposition of rGO/Al2O3 on indium tin oxide (ITO) glass by cyclic voltammetry followed by the deposition of
PEDOT via chronoamperometry. The morphology of PEDOT/rGO-Al2O3 showed the combination of the wrinkled
paper-like structure of rGO and coral-like morphology of PEDOT with nanoparticles of alumina, which gave the
positive synergistic effects of the counter electrode to increase the performance of the DSSC. The electrochemical
analyses indicated that PEDOT/rGO-Al2O3 exhibited a good electrocatalytic activity to act as a counter electrode
in DSSC compared to PEDOT-rGO, PEDOT and rGO. The PEDOT/rGO-Al2O3 achieved power conversion efficiency (PCE) of 2.15%, which is higher compared to PEDOT-rGO (1.00%), PEDOT (0.69%) and rGO (0.09%).
Introduction
In these recent years, many developments have been recognized in
enhancing the natural resources for energy and power supply in order
to improve human life. Generally, dye-sensitized solar cell or known as
DSSC is one of the emerging photovoltaic (PV) devices that is said to be
considered beneficial to humankind. DSSC is used as one of the simplest
forms of PV device that is proved to be efficient in converting solar
energy into electrical energy.
Generally, DSSC consists of four main components i.e. counter
electrode, electrolyte, photoanode and dye [1]. The components work
together to give a positive synergistic effect to obtain high power
conversion efficiency (PCE). The principle of DSSC can be explained
when the photon from the light source that passes through the transparent electrode strike the sensitized photoanode and excited the dye
molecules. The dye molecules can produce electricity once sensitized by
the light. The photoanode will support the dye molecule and transfer
the electrons to the counter electrode. Counter electrode collects the
electrons and will eventually transport the electrons to the electrolyte
and complete the oxidation-reduction cycle [2]. A typical DSSC uses
TiO2 as the photoanode, platinum (Pt) as the counter electrode and
triiodide as the electrolyte [3].
Many types of research have been carried out to replace Pt as a
counter electrode because Pt has some disadvantages such as expensive,
⁎
involve high heat treatment in the fabrication process and it is one of
the rare metals. Metal oxides are one of the materials that are used to
act as a counter electrode in DSSC. Metal oxides are compounds that are
considered stable and environmental friendly [4]. A study reported that
tungsten oxide, WO3 as counter electrode prepared by chemical deposition displayed a PCE of 0.98%. It is found that the WO3 has a large
surface area which is 240.56 m2 g−1, and this helped in increasing the
efficiency of the device. WO3 has a comparable catalytic activity for the
reduction of redox species and is considered as a low cost and abundant
availability [5]. In addition, aluminium oxide doped with carbon nanofibers (CNFs), Al2O3/CNF that was prepared by electrospinning followed by calcination showed an efficiency of 2.84%. The structure of
Al2O3 is embedded to CNFs and it is said to be efficient to transfer the
electrons from the external circuit to triiodide and iodide in redox
electrolyte [6]. Alumina has moderate conductivity and when it was
incorporated with CNFs, the crystallinity of alumina and carbon increased. This will lead to a stronger binding strength between them and
resulted in an increasing conductivity [6]. In addition, this finding
proves that metal oxides do have remarkable properties that can be
used to replace Pt as counter electrodes for DSSC.
Reduced graphene oxide (rGO) can be obtained through several
ways including thermal, chemical or even by electrochemical approaches. The electrochemical methods can produce rGO through the
reduction of the graphene oxide and this method is capable of
Corresponding author at: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
E-mail address: yusran@upm.edu.my (Y. Sulaiman).
https://doi.org/10.1016/j.rinp.2019.102355
Received 6 April 2019; Received in revised form 15 May 2019; Accepted 15 May 2019
Available online 17 May 2019
2211-3797/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Results in Physics 13 (2019) 102355
W.N.A. Wan Khalit, et al.
producing a high quality of rGO [7]. In addition, rGO is resistant to
corrosion of iodide, good reactivity toward triiodide reduction and low
cost if compared to Pt [8]. According to [7], rGO is one of the most
practical to be studied among graphene derivatives because of their
excellent electrical conductivity. Many studies have reported the use of
rGO as counter electrodes in DSSC will help to enhance the PCE of the
photovoltaic device. Ref. [9] reported that tin oxide doped with reduced graphene oxide (SnO2/rGO) nanoparticles as a counter electrode
has PCE of 6.78% due to the positive synergetic effect displayed by
SnO2 that has uniform dispersion on the graphene sheets that lead to
the remarkable electrocatalytic activity for reducing triiodide in DSSC.
RGO exhibits high electron mobility that will improve the transportability of electrons to be reduced to obtain a good efficiency [10]. On
the other hand, a report on molybdenum disulphides/reduced graphene
oxide (MoS2/rGO) as a counter electrode displayed a PCE of 6.04% by
mixing of graphene oxide with ammonium tetrathiomolybdate. The
high PCE of MoS2/rGO as a counter electrode compared with the typical Pt counter electrode in DSSC is due to excellent electrochemical
stability of MoS2/rGO [11]. Copper cobaltite on reduced graphene
oxide (CuCo2O4/rGO) as a counter electrode resulted in a PCE of
6.11%. The counter electrode prepared by solvothermal followed by
annealing treatment of copper cobaltite, CuCo2O4 and dispersed it on
rGO. This high PCE indicated that CuCo2O4/rGO has good catalytic
properties on restoring triiodide [12].
Poly(3,4-ethylenedioxythiophene) (PEDOT) is widely used in the
fabrication of counter electrode in DSSC due to easy to process, remarkable conductivity, good stability and light weight [13–15]. This
conducting polymer is certainly known for having excellent conductivity and chemical stability [16]. Furthermore, [17] demonstrated
that PEDOT can improve the catalytic activity of the redox reaction of
triiodide. Another study conducted by [18] reported that PEDOT as the
counter electrode in DSSC can give a good PCE value where p-toluenesulfonate doped with PEDOT (TsO-PEDOT) and polystyrenesulfonate
doped PEDOT (PSS-PEDOT) showed efficiencies of 4.60% and 2.10%,
respectively.
A combination of metal oxide, carbonaceous material and conducting polymer has produced a synergistic effect that leads to a good
counter electrode with high surface area and high conductivity. A study
revealed that poly(3,4-ethylenedioxythiopheene)-graphene oxide/titanium dioxide (PEDOT-GO/TiO2) as a counter electrode in DSSC has
resulted in a low charge transfer resistance with an efficiency of 1.16%.
This indicated that the incorporation of those materials could enhance
the reduction of triiodide ion due to the excellent conductivity and
stability of PEDOT, high surface area of GO and good photocatalytic
activity of TiO2 [19].
In this study, PEDOT/Al2O3-rGO as a new counter electrode for
DSSC was prepared via two-step depositions i.e. deposition of Al2O3rGO through cyclic voltammetry followed by deposition of PEDOT on
Al2O3-rGO via chronoamperometry. The synergistic effect of high
conductivity PEDOT, high conductivity and high surface area rGO and
high surface area Al2O3 has yielded a higher PCE compared to the
PEDOT-rGO, PEDOT and rGO counter electrode.
was obtained from Graphenea and deionized water from Millipore
system (Mili-Q 18.2 MΩ·cm) was used to prepare solutions. Acetonitrile
and hydrochloric acid were purchased from Riendemann Schmidt.
Preparation of counter electrode for the DSSC
Prior to use, ITO glasses were sonicated using acetone, ethanol and
deionized water for 10 min. The counter electrodes were prepared via
two-steps depositions using a three-electrode system, where silver/
silver chloride (Ag/AgCl) electrode as the reference electrode, Pt wire
as the counter electrode and ITO glass as the working electrode.
Initially, aluminium oxide incorporated with rGO was deposited on ITO
glass from a solution containing 50 mM (Al(NO3)3·9H2O) and 1 mg/mL
of GO. The deposition was performed using cyclic voltammetry between −1.5 V and 1.2 V for 2 cycles at a scan rate of 0.05 V/s. PEDOT
was then deposited on Al2O3-rGO at a constant potential of 1.2 V for
100 s in a solution containing 10 mM of EDOT and 0.1 M of LiClO4 in
acetonitrile. Ag/Ag+ and Pt wire acted as the reference and counter
electrodes, respectively. Pt electrode was fabricated by spin coating as
described in the previous work [20].
Preparation of photoanode
The photoanode was prepared by mixing 25 wt% TiO2 (P25) and
2 mL of tert-butanol. The TiO2 powder was stirred for 30 min until it
fully dispersed and 0.12 mL of TTIP was added to the solution. The
mixture was stirred for 30 min followed by sonicating for 30 min. The
doctor blade technique was used to coat the paste onto the ITO glasses
that were heated for 2 h at 150 °C by using a hotplate. After cooling the
ITO glasses to room temperature, 0.2 mM dye bath N719 dissolved in an
equivalent ratio of acetonitrile and tert-butanol (1:1) was used to immerse the photoanode for 24 h.
Assembly of dye-sensitized solar cell
The TiO2 photoanode and the PEDOT/Al2O3-rGO counter electrode
were assembled together to form the DSSC device by sandwiching them
with I−/I3− based electrolyte. The electrodes were clipped together
properly to prevent the leaking of the electrolyte. The conductive part
of both photoanode and the counter electrode were facing each other,
and the effective area was 0.25 cm2.
Characterization
The counter electrodes were analyzed to determine their properties.
The Fourier Transform Infrared (FTIR) was carried out to determine the
functional groups present on the counter electrode. FTIR was analyzed
by using Shimadzu equipped with universal attenuated total reflectance
(UATR) with the wavenumber between 4000 and 400 cm−1. The X-ray
Diffraction (XRD) analysis was used to determine the diffraction peaks
of the counter electrode by using Shimadzu XRD Diffractometer with Cu
Kα radiation (λ = 1.54 Å) with the specified scan range of 20–60°. The
morphology of each counter electrode was examined using field emission scanning electron microscopy (FESEM JEOL JSM-7600F). A threeelectrode system was used to determine the electrocatalytic activity of
redox electrolyte using cyclic voltammetry (CV) analysis. The prepared
electrodes, platinum wire and Ag/Ag+ were used as working, counter
and reference electrodes, respectively. The CV measurements were
performed in a solution containing 1 mM triiodide and 0.1 M LiClO4 in
acetonitrile. The CV analysis was scan between −1.2 V to +1.2 V using
a scan rate of 50 mVs−1. The electrochemical impedance spectroscopy
(EIS) and Tafel polarization measurements were performed using two
electrode systems consisting of a symmetric counter electrode cell with
Iodolyte Z-100 as a source of electrolyte in dark condition. The open
circuit potential (OCP) and frequency range used in EIS were 0.8 V and
100 kHz to 1 Hz, respectively. Tafel polarization analysis was
Materials and methods
Materials
3,4-Ethylenedioxythiophene (EDOT), titanium dioxide (TiO2,
Degussa P25), titanium isopropoxide (TTIP), lithium perchlorate
(LiClO4), chloroplatinic acid hexahydrate and aluminium nitrate nonahydrate (Al(NO3)3·9H2O) were purchased from Sigma Aldrich. Tertbutanol and acetone were both received from Merck KGaA and indium
tin oxide (ITO) glasses (7 Ω/sq) were obtained from Xinyan Technology
Ltd. Ruthenizer 535-bis TBA (N719) and Iodolyte Z-100 were obtained
from Solaronix SA. Potassium chloride and ethanol were purchased
from Fisher Chemicals and HmbG®, respectively. Graphene oxide (GO)
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Results in Physics 13 (2019) 102355
W.N.A. Wan Khalit, et al.
Fig. 1. FTIR spectra of PEDOT, rGO, PEDOT-rGO and PEDOT/rGO-Al2O3 as
counter electrodes in DSSC.
performed at a scan rate of 10 mVs−1. J-V analysis was conducted with
the presence of light illumination on the counter electrode. This analysis makes use of a two-electrode system where the photoanode was
placed facing the light source with 100 mW·cm−2. From this analysis,
open circuit voltage (Voc) and short circuit current for the counter
electrode can be determined. All the electrochemical measurements
were carried out using potentiostat galvanostat (Autolab 101, Nova
1.11).
Fig. 2. XRD patterns of PEDOT, rGO, PEDOT/rGO and PEDOT/rGO-Al2O3 as
counter electrodes. ♣, ♦ and ♠ symbols represent PEDOT, Al2O3 and rGO, respectively.
plane indicated the presence of the alumina (JCPDS 00-038-0655) [27].
Field emission scanning electron microscopy
Field Emission Scanning Electron Microscopy (FESEM) was conducted to provide insights into the surface morphologies of the counter
electrodes. As shown in Fig. 3a, PEDOT shows the coral-like morphology with the adjoined branches of coral [21]. Fig. 3b shows the
wrinkled paper-like structure of rGO. Meanwhile, for PEDOT-rGO
(Fig. 3c), it indicates that PEDOT and rGO are well-incorporated on the
ITO substrate that eventually resulted in a combination of wrinkled
paper-like morphology of rGO and dense globular morphology of
PEDOT [28]. This morphology contributes to an increased surface area
of the counter electrode compared to solely rGO since the wrinkled
structure in PEDOT-rGO is more prominent. It is observed that PEDOT/
rGO-Al2O3 shows the presence of alumina, rGO and PEDOT as displayed
in Fig. 3d. The wrinkled paper-like structure of rGO and the coral-like
morphology of PEDOT with the nanoparticles of alumina give the positive synergistic effects of the counter electrode to increase the performance of the DSSC.
Results and discussion
Fourier transform infrared spectrum
FTIR was performed to determine the functional groups of the
counter electrodes and the FTIR spectra are shown in Fig. 1. PEDOT
spectrum show bands at 1622, 1174 and 765 cm−1 that are assigned to
the asymmetric stretching mode of C]C, CeOeC bending vibration in
ethylenedioxy group and CeS vibration mode of PEDOT [21]. In addition, a broad peak around 3500 cm−1 is observed which indicates the
OeH stretching vibration of H2O molecules [22]. These PEDOT bands
are also observed in the PEDOT-rGO and PEDOT/rGO-Al2O3 spectra.
Meanwhile, the rGO spectrum shows several peaks at 1543 and
1100 cm−1 that attributed to C]C and CeOH stretching, respectively
[23]. PEDOT-rGO shows a combination of PEDOT and rGO peaks, indicating a successful deposition of the materials. The spectrum of
PEDOT/rGO-Al2O3 shows a sharp peak at 480 cm−1, which is attributed
to the presence of alumina [6], proving that PEDOT/rGO-Al2O3 composite was successfully prepared.
Cyclic voltammetry analysis
CV measurements were carried out by using the three-electrode
system in the presence of triiodide and LiClO4 in acetonitrile solution.
The electrodeposited counter electrodes were analyzed using CV to
determine the electrocatalytic activity. The cathodic peak current
density (Icp) and peak to peak separation potential (Epp) can be obtained
from the CV to indicate the performance of the counter electrodes.
Based on the results obtained (Fig. 4), it is observed that the reduction
occurs between −0.75 and 0.23 V which corresponds to the reduction
of triiodide to iodide (Eq. (1)) while, the oxidation between 0.30 and
0.80 V, which corresponds to oxidation of iodide to triiodide (Eq. (2)).
X-ray diffraction
X-ray Diffraction (XRD) was conducted to determine the phase
identification of crystalline materials and Fig. 2 shows the XRD patterns
for the different counter electrodes. A broad diffraction peak at
2θ = 25° which is attributed to the interchain planar ring stacking of
conducting polymer indexed by (0 2 0) which corresponds to the reflection of PEDOT backbone [24]. A diffraction peak at 2θ = 25° for
rGO is attributed to the (0 0 2) crystal plane assigned as carbon [25].
Meanwhile, the PEDOT/rGO and PEDOT/rGO-Al2O3 composites reveal
a peak at 2θ ∼ 25°, which confirmed the presence of PEDOT and rGO
[26], in which both peaks are overlapped. In addition, PEDOT/rGOAl2O3 diffractogram show peaks at 26.12°, 28.21°, 30.38°, 38.78°,
44.60°, 47.76°, 51.12°, 55.27° and 57.01° which indexed by (0 1 2),
(0 2 1), (4 1 2), (1 1 1), (2 0 0), (6 0 0), (0 2 2), (1 5 1) and (7 2 4) crystal
I3 + 2e
3I
(1)
3I
(2)
I3 + 2e
−2
It is found that the Icp of PEDOT/rGO-Al2O3 (−2.45 mA·cm ) is
much higher compared to rGO (−1.20 mA·cm−2), PEDOT
(−1.50 mA·cm−2) and PEDOT-rGO (−1.98 mA·cm−2). These results
3
Results in Physics 13 (2019) 102355
W.N.A. Wan Khalit, et al.
Fig. 3. FESEM images of (a) PEDOT, (b) rGO, (c) PEDOT-rGO and (d) PEDOT/rGO-Al2O3.
activity toward redox reaction. This could be due to the positive synergetic effect displayed by Al2O3 that exhibits a good corrosion resistant [29] incorporated with PEDOT that has good conductivity [13]
together with the high surface area of rGO that enhance the redox reaction [30].
Electrochemical impedance spectroscopy
EIS measurements were performed to analyze the kinetics of
charge transfer of the counter electrodes. Charge transfer resistance
(Rct) indicates the charge transfer resistance between the electrolyte
and counter electrode interface that can be obtained from the diameter of the semicircles and the series resistance (Rs) can be obtained
from the interception of Z’ axis. As shown in Fig. 5, all the counter
electrodes show one semicircle and rGO shows the largest semicircle
while PEDOT/rGO-Al2O3 shows the smallest semicircle, implying
PEDOT/rGO-Al2O3 has the most excellent electrocatalytic activity for
the reduction of triiodide due to the high surface area of rGO and
Al2O3 provides more active sites for the reduction of triiodide that
enhances the efficiency of the device. Fig. 5 shows the trend for the Rct
as follow: rGO (45.0 Ω·cm2) > PEDOT (1.4 Ω·cm2) > PEDOT-rGO
(1.3 Ω·cm2) > PEDOT/rGO-Al2O3 (0.6 Ω·cm2), proving that PEDOT/
rGO-Al2O3 is the best counter electrode that exhibited a good electrocatalytic property. These results are in accordance with the CV
analysis which suggesting PEDOT/rGO-Al2O3 as the best counter
electrode in catalyzing redox reaction as a low Rct indicates superior
redox reaction toward the reduction of triiodide. However, the trend
of Rs is quite varied from the trend of Rct. The trend for Rs is as follow:
Fig. 4. CV analysis of PEDOT-rGO/Al2O3, PEDOT-rGO, PEDOT and rGO as the
counter electrode in DSSC in a solution of 1 mM triiodide and 0.1 M LiClO4 in
acetonitrile solution with a scan rate of 0.05 V/s.
indicate that PEDOT/rGO-Al2O3 has an excellent electrocatalytic activity compared to the other counter electrodes. In addition, the Epp of
PEDOT/rGO-Al2O3 (0.47 V) is smaller than PEDOT-rGO (0.52 V), rGO
(0.57 V) and PEDOT (0.95 V) suggesting a greater electrocatalytic
4
Results in Physics 13 (2019) 102355
W.N.A. Wan Khalit, et al.
Fig. 6. Tafel polarization measurement with the different counter electrodes
used which are PEDOT/rGO-Al2O3, PEDOT-rGO, PEDOT and rGO respectively.
Fig. 5. Electrochemical impedance spectra of different counter electrodes in
DSSC which are PEDOT/rGO-Al2O3, PEDOT-rGO, PEDOT and rGO. Insets graph
shows the EIS result for PEDOT/rGO-Al2O3, PEDOT-rGO and PEDOT counter
electrodes.
Table 2
The Tafel parameters for PEDOT, rGO, PEDOT-rGO and PEDOT/rGO-Al2O3.
Table 1
Rct and Rs data from various counter electrodes.
Counter electrode
Rct (Ω·cm2)
RS (Ω·cm2)
rGO
PEDOT
PEDOT-rGO
PEDOT/rGO-Al2O3
45.0
1.4
1.3
0.6
25.3
29.9
23.1
23.8
Counter electrode
Jlim (mA·cm−2)
Jo (mA·cm−2)
PEDOT
rGO
PEDOT-rGO
PEDOT/rGO-Al2O3
1.279
0.853
1.332
1.413
0.344
−0.015
0.449
0.708
EIS analyses, providing PEDOT/rGO-Al2O3 as a propitious counter
electrode in DSSC.
PEDOT > rGO > PEDOT/rGO-Al2O3 > PEDOT-rGO (Table 1).
PEDOT-rGO exhibit the lowest Rs value compared to the PEDOT/rGOAl2O3 because the former possesses a high conductivity than the latter.
Even though the addition of Al2O3 increases the surface area of the
counter electrode, the low conductivity of the Al2O3 affected the
electrons transferring process [6].
Photocurrent-voltage curve analysis
The photocurrent-voltage curve analysis (J-V) was performed for all
the counter electrodes as shown in Fig. 7 and the data are summarized
in Table 3. From the analysis, it is observed that the short circuit current
(Jsc) of PEDOT/rGO-Al2O3 is the highest compared to Pt, PEDOT-rGO,
PEDOT and rGO counter electrodes while PEDOT-rGO reveals the
highest open circuit voltage (Voc) followed by Pt, PEDOT/rGO-Al2O3,
PEDOT and rGO. These resulted in the power conversion efficiency of
Tafel polarization measurement
Tafel polarization measurements were conducted to further study
the electrocatalytic activity of the counter electrodes. Basically, Tafel
curve has three crucial zones which are polarization zone (curve at low
potential), Tafel zone (middle potential with sharp slope) and diffusion
zone (curve at high potential) [31]. Limiting diffusion current density
(Jlim) can be obtained from the intersection at the y-axis of the Tafel
curve whereas the exchange current density (Jo) can be obtained
through the intersection of the linear line at 0 V with the tangent line
from the polarization curve [32]. Jlim indicates the diffusion velocity of
I−/I3− in the electrolyte whereas Jo represents the reduction activity of
I3− [33]. Fig. 6 shows the Tafel curves and Table 2 summarizes the
value of Jlim and Jo for rGO, PEDOT, PEDOT-rGO and PEDOT/rGOAl2O3. Based on the results obtained, Jlim for PEDOT/rGO-Al2O3 is
1.413 mA·cm−2, which is the highest Jlim obtained compared to the
other counter electrodes, indicating PEDOT/rGO-Al2O3 has the best
performance in the diffusion velocity of I−/I3− compared to PEDOT,
rGO, PEDOT-rGO and PEDOT/rGO-Al2O3. From the Tafel curve, Jo of
rGO, PEDOT, PEDOT-rGO and PEDOT/rGO-Al2O3 yielded are
−0.015 mA·cm−2, 0.344 mA·cm−2, 0.449 mA·cm−2 whereas, PEDOT/
rGO-Al2O3 displays the highest value of Jo (0.708 mA·cm−2). These
results indicate that PEDOT/rGO-Al2O3 is the best for the reduction of
triiodide compared to other counter electrode s due to the synergistic
effect of the materials. The Tafel results are in agreement with CV and
Fig. 7. J-V analysis with different counter electrodes used; PEDOT/rGO-AL2O3,
Pt, PEDOT-rGO, PEDOT and rGO.
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Results in Physics 13 (2019) 102355
W.N.A. Wan Khalit, et al.
Table 3
Photovoltaic parameters of DSSC with different types of the counter electrode
fabricated and comparison with literature.
Counter electrodes
Jsc (mA·cm
PEDOT:PSS
PEDOT:PSS
rGO
PEDOT/rGO-Al2O3
11.00
3.36
3.23
7.40
−2
)
Voc (V)
FF (%)
ƞ (%)
Ref.
0.68
0.60
0.60
0.58
0.28
0.52
0.39
0.50
2.10
1.06
2.08
2.15
[18]
[37]
[36]
This work
[11]
[12]
[13]
[14]
[15]
PEDOT/rGO-Al2O3, which is 2.15% followed by Pt (1.14%), PEDOTrGO (1.00%), PEDOT (0.69%) and rGO (0.09). The results are in
agreement with CV, EIS and Tafel polarization measurements. Alumina
has a high surface area that enables more active sites for the redox
reaction and resulted in higher efficiency of the counter electrode.
While, rGO has a high surface area which improves the reduction of
triiodide to iodide [34]. Moreover, the deposited PEDOT on Al2O3 and
rGO improved the electrocatalytic activity of the fabricated counter
electrode due to the superior conductivity of PEDOT [35]. The combination of these materials proves that the synergistic effects of each
material lead to better efficiency of the device compared to an individual material. The PCE of the PEDOT/rGO-Al2O3 is higher that rGO
reported by [36] (2.08%), PEDOT:PSS counter electrode prepared by
[18] (2.10%) and [37] (1.06%).
[16]
[17]
[18]
[19]
[20]
[21]
[22]
Conclusion
PEDOT/rGO-Al2O3 was successfully fabricated via two steps deposition. PEDOT deposited on rGO-Al2O3 exhibited an excellent electrocatalytic activity that resulted in the efficiency of 2.15% of the DSSC
device compared to the other counter electrodes fabricated in this work.
This facile process and low-cost fabrication make PEDOT/rGO-Al2O3 as
a promising candidate toward a superior performance of DSSC for the
benefit of humankind.
[23]
Acknowledgement
[27]
This research work was supported by the Universiti Putra Malaysia
Research Grant (UPM/800-3/3/1/GPB/2018/9659200).
[28]
[24]
[25]
[26]
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