Harnessing Nature's Colors

Hardeli, et al.

Articles

MOLEKUL

eISSN: 2503-0310

https://doi.org/10.20884/1.jm.2025.20.2.14891

Harnessing Nature's Colors: Combining Plant Pigments and Metal Coatings for Dye-Sensitized
Solar Cell
Hardeli1, Hary Sanjaya1, Lasmi Yunita1, Indri Panca Novita1, Nurul Fadilah Agdisti1,
Rahmaneta Luli1, Putri Permatasari2*
Department of Chemistry, Universitas Negeri Padang, Padang 25131, Indonesia
Department of Materials Science and Processing, Gifu University, Gifu 501-1113, Japan
1

2

*Corresponding author email: putri.permatasari.s4@s.gifu-u.ac.jp

Received February 07, 2025; Accepted May 08, 2025; Available online July 20, 2025
ABSTRACT. This study aims to improve the efficiency of dye-sensitized solar cells (DSSCs). To overcome the recombination
problem in the commonly used TiO2 semiconductor, we performed electrodeposition of ferrous metal (Fe) on TiO 2. XRD
characterization showed that after Fe electrodeposition, the crystal structure of TiO₂ remained in the anatase phase without
significant changes compared to before deposition while based on SEM-EDS results, Fe was dispersed to form small
agglomerates that functioned as metal contacts to reduce electron recombination. We also investigated the use of
anthocyanins from various natural sources, including jengkol skin, senduduk fruit, mangosteen skin, and red grape skin.
These anthocyanins were copigmented with salicylic acid. UV-Vis spectroscopy revealed that copigmentation caused a
bathochromic shift and FTIR spectrum confirmed strong interaction between anthocyanins and salicylic acid through
hydrogen bond formation. The combination of TiO2-Fe layers with pigmented dyes resulted in diverse DSSC efficiencies,
with mangosteen peel showing the best performance (4.123%), followed by senduduk fruit (3.495%), grape peel (2.569%),
and jengkol peel (1.925%). The increase in efficiency from 1.189% (without Fe coating) to 1.700% (with Fe coating)
demonstrates the potential of this technique. The small TiO 2 crystal size (about 61.8 nm) also contributes to the increased
surface area, enhancing dye absorption and solar cell performance. The electrical efficiency showed that the combination
of TiO2-Fe with copigmented anthocyanins from mangosteen skin produced DSSCs with the highest efficiency,
demonstrating the potential of this approach to improve the performance of natural dye-based solar cells.
Keywords: Co-pigmentation, dye-sensitized solar cell, Fe electroplating, natural dye.

INTRODUCTION
Energy is one of the biggest challenges we face
in this modern era (Sofian et al., 2024; Gorinanet al.,
2024; Jiglau et al., 2024; LaBelle, 2023; Pashiri et al.,
2022). Along with rapid economic and population
growth, energy demand continues to rise sharply
(Ahmed et al., 2023; Mombekova et al., 2024;
Wang et al., 2023). While fossil fuels still dominate
the main energy sources, we are on the verge of a
major shift towards the era of renewable energy
(Nijsse et al., 2023; Sahin et al., 2024). Amidst
various renewable energy options such as wind,
hydro, and biomass, solar energy is emerging as
a very promising candidate, especially in a tropical
country like Indonesia (Pambudi et al., 2023;
Silalahi et al., 2021). Indonesia's geographical
location on the equator provides the advantage of
abundant sun exposure throughout the year, making
it an ideal location for the development of solar cell
technology (Bernabé-Poveda et al., 2024; Pollin,
2023; Wuryanti & Megawati, 2019).
One exciting innovation in solar cell technology is
the Dye-Sensitized Solar Cell (DSSC) (Badawy et al.,

2024; Badawy et al., 2022; Dragonetti & Colombo,
2021; Muñoz-García et al., 2021; Rahman et al.,
2023). DSSCs offer a unique and efficient approach in
converting solar energy into electricity. Unlike
conventional silicon solar cells, DSSCs use organic
dyes to absorb light (Badawy et al., 2024; Barichello et
al., 2024; D’Amico et al., 2023; Zdyb & Krawczak,
2021). The advantages of DSSCs lie in their flexibility
and relatively low production costs (Badawy et al.,
2024; Mariotti et al., 2020). The cell does not require
high-purity materials, making the production process
simpler and more economical (Hardeli et al., 2023;
Kusuma, 2017). The working principle of DSSCs is also
interesting: dye molecules absorb photons, while
nanocrystalline inorganic semiconductors play a role in
charge separation (Badawy et al., 2024; Darmawan &
Nuzuluddin, 2023; Rahman et al., 2023; Sharma et
al., 2018a; Widiatmoko et al., 2024). This approach
differs from silicon-based solar cells, where silicon
plays a dual role in light absorption and charge
separation (Lee et al., 2014).
Titanium dioxide (TiO2) is often the first choice as a
semiconductor in DSSCs. Its nature as an n-type

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semiconductor with a relatively wide band gap (around
3.2 eV) makes it ideal for this application (Abdullah et
al., 2017; Benesperi et al., 2018; Longo & De Paoli,
2003; Sharma et al., 2018b). The lower conduction
band position of TiO2 from the LUMO (Lowest
Unoccupied Molecular Orbital) level of the dye
facilitates efficient electron transfer (Badawy et al.,
2024; Elmorsy et al., 2023; Leela Devi, De, Kuchhal,
& Pachauri, 2024; Mustafa et al., 2023). In addition,
TiO2 also excels in terms of price and minimal
environmental impact (Chauke et al., 2024; Gatou et
al., 2024; R. Li et al., 2020; Racovita, 2022;
Rodríguez-Rojas et al., 2024). However, the use of
TiO2 also faces challenges, especially the problem of
electron recombination (Bonomo et al., 2020). This
phenomenon occurs when free electrons release
energy and return to the valence band, reducing cell
efficiency (Leijtens et al., 2016; Sherkar et al., 2017).
To address this, metal electrodeposition techniques
on TiO2 layers are emerging as a promising solution.
In this study, we explored the use of ferrous metal (Fe)
to improve the performance of DSSCs. The selection of
Fe was based on several considerations. Fe's electron
configuration like that of ruthenium and osmium metals that have been shown to yield high efficiencies
in dye solar cells - was the main reason (Chen et al.,
2024; Nyamukamba et al., 2018; Rahman et al.,
2023; Thu et al., 2016). In addition, Fe has
advantages in terms of abundance, ease of access,
and lower cost (Baruah et al., 2024; Emerson et al.,
2024). Fe's characteristics of being soluble in polar
solvents and having a UV-Vis wavelength of 551 nm
also favor its use in DSSCs (Bella et al., 2015; Mauri et
al., 2022; Setyawati et al., 2017; Tuharin et al., 2020).
Another key aspect in DSSC optimization is dye
selection (Arjmand et al., 2022; Badawy et al., 2024;
Azra et al., 2024; Rahman et al., 2023; Triyanto et al.,
2024). Although TiO2 can only absorb 5% of the solar
light spectrum in the UV range, the use of appropriate
dyes can significantly increase the light absorption
efficiency (Augustowski et al., 2021; Chauke et al.,
2024; Elmorsy et al., 2023; Gnida et al., 2021; Hsu et
al., 2024). In this context, natural dyes offer several
advantages, including abundant availability, low cost,
and simple extraction process (Li et al., 2022; Novita
et al., 2024; Salauddin et al., 2021). Anthocyanins, as
one of the natural dyes, have attracted the attention of
researchers to be developed as sensitizers in DSSCs
(Hardeli et al., 2022; Mulijani et al., 2020; Setyawati
et al., 2017). Its ability to expand the light absorption
area has the potential to increase cell efficiency. The
presence of carbonyl and hydroxyl groups in the
anthocyanin molecular structure facilitates good
attachment to the TiO2 layer, which in turn increases
the energy conversion efficiency (Calogero et al.,
2012; Dai & Rabani, 2002; Maurya et al., 2016;
Prabavathy et al., 2017; Subramanian & Wang,
2012). In this study, we explored the use of
anthocyanins from various natural sources, including

jengkol (Pithecellobium jiringa B.) skin, senduduk
(Melastoma malabathricum L.) fruit, mangosteen
(Garcinia mangostana L.) skin, and red grape (Vitis
vinifera) skin. However, given the easily oxidized and
degraded nature of anthocyanins, we applied a copigmentation technique with salicylic acid to improve
their stability (Zhu et al., 2020).
The main objective of this study is to evaluate the
effect of Fe electrodeposition on the performance of
TiO2-based DSSCs, using co-pigmented anthocyanins
from various natural sources as colorants. Through this
approach, we hope to make significant contributions in
the development of more efficient and sustainable
DSSCs, opening new avenues in the utilization of solar
energy in the future.

EXPERIMENTAL SECTION
Materials
Red grape peel (Vitis vinifera), mangosteen peel
(Garcinia mangostana L.), senduduk fruit (Melastoma
malabathricum L.), and jengkol peel (Pithecellobium
jiringa B.) were among the natural materials that were
used as samples. Fe(NO₃)₃·9H₂O (≥99%, SigmaAldrich), TiO₂ Degussa P-25 (≥99%, Evonik), distilled
water, ethanol (≥99.8%, Merck), salicylic acid (≥99%,
Sigma-Aldrich), hydrochloric acid (HCl, 37%, Merck),
KCl (≥99.5%, Sigma-Aldrich), KI (≥99%, SigmaAldrich), I₂ (≥99.8%, Sigma-Aldrich), polyethylene
glycol (PEG, MW 6000, Sigma-Aldrich), Whatman filter
paper No.42, and indium tin oxide (ITO) glasses (8–
12 Ω/sq, Sigma-Aldrich) were among the materials
used. ITO (Indium Tin Oxide) glass is a transparent
glass coated with indium-tin oxide, which is electrically
conductive and transparent to visible light, so it is
widely used as an electrode in DSSC.
Preparation of ITO Glass and TiO2 Layer
After getting cut to 1.25 x 1.25 cm, ITO glass was
cleaned with an ultrasonic cleaner and immersed in
70% alcohol for 60 minutes. The purpose was to get
rid of anything that would interfere with the ITO glass
coating process. 0.5 grams of polyvinyl alcohol (PVA)
were dissolved in 50 milliliters of distilled water. To
make a suspension, the mixture was heated to 80 °C
on a hot plate while being agitated. 0.5 grams of
powdered TiO2 were added to the solution. To create
a fine paste for the coating procedure, the mixture was
then crushed using a mortar and pestle. The doctor
blade procedure was then used to smooth the TiO2
paste. After that, the glass was heated for half an hour
on a hot plate to remove the water content of TiO2.
Fe Metal Electroplating
A carbon electrode and a TiO2 electrode are used in
the procedure. A 0.2 M electrolyte of Fe(NO3)3 was
utilized. Following the electroplating procedure, the
TiO2 layer containing Fe was dried for 30 minutes at
100 degrees Celsius on a hot plate. The titanium used
was TiO2 Degussa P-25, which has a nanoparticle size
and has two phases, 80% anatase, and 20% rutile. In
the prepared DSSC, titanium dioxide was coated on

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Hardeli, et al.

the ITO glass using the Doctor Blade method. Titanium
dioxide was coated on the ITO substrate in a paste
form using polyvinyl alcohol and water. The TiO2 layer
was then heated to 100C to form a TiO2 layer that is
firmly attached to the ITO glass. Electrodeposition
was carried out in the prepared TiO2 layer using
Fe(NO3)3 as an electrolyte solution and Fe metal
as an electrode with 9V for 20 seconds. The reactions
that occur at the anode and cathode can be seen in
Figure 1. The layer deposited with Fe metal was
dried in an oven at 70C for 10 minutes, then put in
a desiccator. Heating at a low temperature was
done to prevent damage to the layer that has been
deposited with Fe metal.
Thin Film Characterization on Glass Surface
X-ray diffraction (XRD) was used to determine the
crystal structure of both Fe-TiO2 and TiO2 powder by
comparing their peaks. The physical form of the active
layer and the presence of Fe metal on the TiO2 layer
were both examined with Scanning Electron
Microscopy (SEM). Characterization was carried out at
a compression of 10 pa and a voltage of 20 kV.
Preparation of Dye
50 milliliters of 96% ethanol and 10 milliliters of 1M
HCl were used to extract 100 grams of each of the
peels from jengkol, senduduk fruit, mangosteen, and
red wine. The extraction procedure was conducted
in a dark environment. To separate the residue, the

extraction was filtered using Whatman filter paper No.
42 after a 24-hour period. The solvent was then
extracted from the filtrate using a rotary evaporator.
The extract was kept in opaque. To check if
anthocyanins were still present, the residue was heated
to 100°C for five minutes while 2M HCl was added.
The results were said to be good when a crimson color
appeared. Anthocyanin extraction methods are
generally carried out using polar solvents such as
ethanol, methanol, or dilute acids to increase the
solubility and stability of the pigment (Zhu et al., 2020;
Salauddin et al., 2021). Previous studies have shown
that the use of acidic solvents can help maintain the
anthocyanin structure and increase extraction efficiency
(Calogero et al., 2012).
Dyes Characterization
The absorbance of the dye that had been copigmented with salicylic acid was measured using the
Ultraviolet-Visible (UV-Vis) Spectroscopy. Additionally,
the impacts of the dye co-pigmentation procedure were
also identified.
The
Agilent
8435
UV-Vis
spectrophotometer was used to assess. The light's
wavelength ranges from 400 to 800 nm. The purpose
of the PerkinElmer FTIR was to identify the kinds of
bonds and functional groups present in the
anthocyanins that were extracted. An analysis was
carried out by examining a certain spectrum or peak
that denoted a specific functional group.

Anode : Fe (s) → Fe2+ (aq) + 2e- (unstable)
Fe2+ (aq) → Fe3+ (aq) + e-

Cathode: Fe3+(aq) + e- → Fe2+(aq)
Fe2+(aq) + 2e- → Fe (s)

Anode :
Carbon

Cathode:
TiO2 layer on
ITO surface

Fe(NO3)3
Figure 1. Schematic of the electrodeposition of Fe on TiO2

eꟷ

ITO Glass as Substrate
TiO2-Fe soaked with Anthocyanins Co-pigmented
with Salicylic Acid as Dye

Load

Electrolyte
Graphite as Counter Electrode

eꟷ

ITO Glass as Substrate

Figure 2. Structure of the dye-sensitized solar cells (DSSC) with TiO2-Fe and natural dye
co-pigmented with salicylic acid.
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Preparation of Semi-Solid Electrolyte
First, 6 mL of acetonitrile was used to dissolve 0.498
g of KI. Separately, 6 mL of acetonitrile and 0.076 g of
I₂ were combined and stirred until the mixture was
uniform. The electrolyte solution was then created by
combining these two solutions. 2.4 g of PEG was then
added, and the mixture was stirred until a gel was
formed.
Preparation of Counter Electrode
The carbon source for the counter electrode was
graphite. It was applied on ITO glass by heating the
conductive surface with a candle. After 30 minutes of
heating at 450°C, the coated glass was progressively
cooled to 70°C and allowed to cool down to room
temperature.
Solar Cell Fabrication
Following the creation of the DSSC's component
parts, the solar cells were assembled. The sandwichlike structure of the DSSC components was put together
in the sequence seen in Figure 2. The bottom layer is
ITO glass substrate that has been coated with graphite
as an electrode counter. then the electrolyte is the next
layer. after that the TiO2-Fe layer that has been soaked
with Anthocyanins Co-pigmented with Salicylic Acid is
coated on the surface using the doctor blade method
which is then covered with ITO glass again as the
outermost layer.
Solar Cell Electric Current Testing
Solar cell voltage and current was monitored using
an automated multimeter. UV rays were used as a light
source. Because it is feared that varied light intensities
will be produced if tested directly under the sun,
influencing computing efficiency, light sources from
ultraviolet lamps are used to get an exact and
consistent
source.
The
DSSC's
photovoltaic
performance was assessed by measuring currentvoltage (I-V) under a simulated solar light source (AM
1.5G, 100 mW/cm²). A digital source meter was used
to measure electrical current and voltage while altering
the external load resistance. The short-circuit current
(Isc) and open-circuit voltage (Voc) were calculated
directly from the I-V curve. The photocurrent
generation was examined using the conventional diode
(equation 1). I₀ represents the reverse saturation
current, q the electron charge, V the applied voltage, k
the Boltzmann constant, and T the absolute
temperature. Equations 2 and 3 were used to obtain
the fill factor (FF) and total power conversion efficiency
(η). where Vmp and Imp are the voltage and current at
the maximum power point, respectively, and Pin
represents the incident light power.
𝒒𝑽

𝑰 = 𝑰𝟎 (𝒆𝒌𝑻 − 𝟏)

(1)

𝑽𝒎𝒑 𝑰𝒎𝒑

(2)

𝑭𝑭 =
𝜼=

𝑽𝒐𝒄 𝑰𝒔𝒄
𝑷𝒐𝒖𝒕
𝑽𝒐𝒄 𝑰𝒔𝒄 𝑭𝑭
𝑷𝒊𝒏

=

𝑷𝒊𝒏

× 𝟏𝟎𝟎%

(3)

RESULTS AND DISCUSSION
Dye Characterization
Dye-sensitized solar cells (DSSCs) use dyes to
enhance their ability to absorb sunlight. The ideal dye
should be able to absorb visible light strongly, stick to
the semiconductor surface, and have high stability
when oxidized. Anthocyanins are one of the natural
dyes that can potentially be used in DSSCs. However,
anthocyanins have the disadvantage of being easily
damaged and oxidized. To overcome this problem, a
co-pigmentation
method,
which
combines
anthocyanins with other molecules such as salicylic
acid to improve their quality can be used. Through the
co-pigmentation process, anthocyanins can experience
significant improvements in terms of thermal stability,
light-absorbing ability and durability. This process
shifts the light absorption to longer wavelengths,
thereby increasing the efficiency of the solar cell. In this
study, we used various natural dye sources such as
jengkol skin, senduduk fruit, mangosteen skin, and red
grape skin. Characterization of the dyes was done
using two main instruments: UV-Vis spectrophotometer
to analyze the optical properties and FTIR to identify the
functional groups present in the dyes. Figure 3 shows
that co-pigmentation successfully enhances the
performance of anthocyanins as photosensitizers in
dye-sensitized solar cells.
It was discovered that the dye spectrum produced
by the four samples was almost the same. The
infrared interpretation revealed the presence of the
alcohol (ꟷOH) group, as indicated by a sharp
absorption at 3341.11cm-1. Anthocyanins are
compounds with a conjugated phi system that can
absorb visible light. An alkene bond (C═C) was
demonstrated at 1626.11cm-1, supported by an
aromatic C-H bond at 779.19 cm-1 and an aromatic
ether bond at 1247.82 cm-1, both of which indicated
the presence of a flavilum group in anthocyanidins.
Furthermore,
the
presence of CꟷOꟷC bonds
suggests the formation of bonds between
anthocyanidins and sugar groups, supported by CꟷH
bonds from the 1440.35 cm-1 methyl group, which
indicates the formation of a bond on R1 or R2 of
anthocyanins. Based on the results of FTIR
identification, it can be concluded that there were
anthocyanin compounds in the jengkol skin, senduduk
fruit, mangosteen peel, and grape skin dye extract.
Therefore, it can be used as dyes in DSSC.
The UV-Vis spectrophotometer test aims to observe
the effect of salicylic acid copigmentation in the dye
extract. The interaction between copigment and dye is
an
intermolecular
interaction.
Salicylic
acid
copigmentation will produce anthocyanins with better
thermal stability and the bathochromic effect, where
there is a shift in maximum absorbance. The UV-Vis
test results show that the dye extracts from different
sources have different maximum wavelengths (λmax.).

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Hardeli, et al.

2,0

Pure Mangosteen peel

Absorbance (A)

Pure Jengkol Skin

1,5
1,0
0,5
0,0

405
425
445
465
485
505
525
545
565
585
605
625
645
665
685
705
725
745
765
785

0,7
0,6
0,5
0,4
0,3
0,2
0,1
0,0

400
420
440
460
480
500
520
540
560
580
600
620
640
660
680
700
720
740
760
780
800

Absorbance (A)

Figure 3. Spectra FTIR interpretation of various salicylic acid pigmented dyes: mangosteen peel (blue), jengkol
skin (orange), senduduk fruit (black), and grape skin (green).

Wavelength (nm)
Pure Senduduk Fruit

Absorbance (A)

1,0

Wavelength (nm)
5,0

Pure Grape Skin

Absorbance (A)

1,5

4,0

3,0
2,0

0,5

1,0

0,0

405
425
445
465
485
505
525
545
565
585
605
625
645
665
685
705
725
745
765
785

405
425
445
465
485
505
525
545
565
585
605
625
645
665
685
705
725
745
765
785

0,0
Wavelength (nm)

Wavelength (nm)

4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0,0

Copigmented Grape Skin
copigmented Mangosteen peel

Copigmented Jengkol Skin
Copigmented Senduduk Fruit

400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
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630
640
650
660
670
680
690
700
710
720
730
740
750
760
770
780
790
800

Absorbance (A)

Figure 4. The absorbance of various salicylic acid pigmented dyes: mangosteen peel, jengkol skin, senduduk
fruit, and grape skin

Wavelength (nm)

Figure 5. Comparison of the results of co-pigmentation of anthocyanins from various natural sources
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For jengkol skin, the absorbance is shifted from a
maximum wavelength of 515 nm without
copigmentation to 520 nm for the copigmented dye.
Senduduk fruit shifts from 505 nm to 510 nm,
mangosteen shifts to 515 nm with increased intensity,
and grape skin shifts from 525 nm to 535 nm. This
increase happens because salicylic acid adds π
electrons to anthocyanins so that light absorption will
shift to longer wavelengths. Copigments will increase
the coordination between anthocyanins and others,
resulting in interactions. The absorption of light at
longer wavelengths can increase the absorption of
sunlight by DSSC. The complex formation between
copigments and anthocyanins also affects the
absorption of dyes. Based on the data, copigmentation
shows an increase in absorption intensity at longer
wavelengths, thereby increasing light absorption and
enhancing the positive effect on DSSCs.
Fe-TiO2 Layer
ITO glass is a transparent conductive glass (TCO).
It will serve as both a framework and a layer through
which electrons can flow. The counter electrode used
was black carbon. As a cell photocatalyst, titanium
dioxide was utilized as a semiconducting layer. Heating
the TiO2 layer used in the Doctor Blade method at a

low temperature can prevent damage to the heatsensitive ITO glass so that the resistance of the cell can
be reduced.
In the electrodeposition process, the Fe electrode
acts as the anode. The electrochemical reaction that
occurs at the anode was the oxidation of Fe metal to
Fe2+ ions, but Fe2+ ions were less stable, and Fe3+ ions
were formed. At the cathode, precursor solution Fe3+
ions reduced Fe metal and deposited on the surface of
the TiO2 layer.
The XRD characterization aims to determine the
structure and crystal size of TiO2 coated on ITO glass
before and after Fe metal electrodeposition. The crystal
structure and size of TiO2 significantly affect the
efficiency of the resulting DSSC because it affects the
surface area of dye absorption. The characterization
results using XRD are in the form of a diffraction pattern
(diffractogram) consisting of peaks characterization of
TiO2, as shown in Figure 6 with the interpretation of the
data in Tables 1 and 2.
Based on Figure 6, there were characteristic peaks
of TiO2. The peak with the highest intensity of TiO2 was
at 25.33. The data interpretation card d(Å) for crystals
was close to 3.5154, 2.3732, and 1.8935. The d(Å)
peaks of TiO2 were close to the interpretation card of
3.5157 (Table 1).

Tabel 1. TiO2 layer interpretation
d(Å)
I/I0
Β
2θ
25.33 3.5157 1000.00 0.0023
37.83 2.3783
121.59 0.0023
48.06 1.8931
140.44 0.0023
48.21 1.8877
106.93 0.0023
54.07 1.6960
71.50 0.0017

Tabel 2. TiO2-Fe layer interpretation
D (nm)
61.8439
63.7834
66.0648
66.1034
91.6499

2θ
25.23
37.73
47.97
53.82
55.00

d(Å)
I/I0
3.5266 1000.00
2.3821 140.27
1.8950 148.28
1.7017
83.43
1.6683
85.53

Β
D (nm)
0.0023 61.8317
0.0035 41.9023
0.0017 89.3500
0.0023 67.6661
0.0023 68.0252

Figure 6. Difratogram of XRD analysis for TiO2 before and after electrodeposition

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The crystal size of TiO2 affects the surface area,
which affects the efficiency of the cell. The crystal size
of the XRD data can be calculated using the Scherrer
equation.
𝑲𝝀
𝑫=
(1)
𝜷𝒄𝒐𝒔𝜽

Where D is the crystallite size in nanometers (nm), K is
the Scherrer constant, λ = 1.5406 Å. The parameter β
indicates the full width at half maximum (FWHM) of the
diffraction peak in radians, while θ is the diffraction
angle (Bragg angle) in degrees. This equation is used
to determine the crystallite size based on the
broadening of the diffraction peaks in the XRD pattern,
which provides important information about the
crystallinity of the material.
The calculated crystal size of TiO2 was 61.8439
nanometers. The nanometer-sized titanium dioxide
crystals enhance the performance of the DSSC.
Titanium dioxide is a crystal with a tetragonal
structure and anatase phase. The small size of TiO2
crystals with the anatase phase causes the surface
area
to increase so that the absorption of

anthocyanins will be higher, and the performance of
solar cells will increase.
The TiO2 layer deposited with the highest intensity
Fe metal was found at 2θ = 25.23, with a d(Å) value
of 3.5266. From the calculation result, the crystal size
of TiO2 was 61.8317 nm. When compared with the
size of the crystal before the deposition of Fe metal,
there was no significant change in the crystal size. It
was possible because Fe metal only forms metal
contacts with TiO2.
The crystal size of TiO₂ influences the surface area,
which in turn affects the efficiency of the DSSC. As
shown in our XRD results, the TiO₂ crystal size is
approximately 61.84–91.65 nm. Smaller crystal sizes
provide a larger surface area for dye adsorption,
enhancing light absorption and electron injection. This
improves charge separation and reduces electron
recombination, leading to better DSSC efficiency. Our
findings, as shown in Table 3, confirm that smaller
TiO₂ crystals contribute to higher photocurrent and
overall efficiency.

Clumps formed due to
Fe electrodeposition

Element
Weight %
Atomic %
Net Int.
Error %
Kratio
Z
A
F

OK
45.060
71.420
480.610
10.280
0.059
1.125
0.116
1.000

Ti K
48.14
25.49
2296.87
1.53
0.43
0.88
1.00
1.00

Fe K
6.80
3.09
185.94
3.49
0.05
0.87
0.94
1.01

Figure 7. SEM-EDS Test Results
355

Molekul, Vol. 20. No. 2, July 2025: 349 – 361

Figure 8. I-V characteristic curves for TiO2 electrodes with and without Fe deposition and when the dye is added.
Table 3. DSSC efficiency of Fe electrodeposition on TiO2 and dye extracts from natural ingredients.
TiO2
TiO2-Fe

Jengkol peel

Efficiency (%)

Grape peel
Senduduk fruit
Mangosteen Peel
4
3,5
3
2,5
2
1,5
1
0,5
0

Voc
0.35
0.45
0.35
0.5
0.48
0.36

Isc (mA)
2.17
1.84
2.40
1.62
1.75
2.39

Jsc
0.11
0.11
0.16
0.15
0.21
0.32

FF
0.76
0.83
0.84
0.81
0.84
0.86

efisiensi
1.189
1.700
1.925
2.569
3.495
4.123

4.123
3.459
2.569

1.925

Jengkol peel

Senduduk fruit

Mangosteen peel

Grape peel

Figure 9. Curve comparison of various anthocyanin sources on the efficiency of DSSC
356

Harnessing Nature's Colors

Hardeli, et al.

SEM-EDS analysis was performed to understand the
surface structure of the TiO2-Fe layer, especially how
Fe is dispersed on it. The observations show that Fe
forms small clumps that are evenly distributed over the
TiO2 layer. These Fe clumps play an important role as
metal contacts that prevent the electrons in the dye
from recombining with the electrolyte, while
accelerating the flow of electrons towards the ITO glass
which has high conductivity. The presence of Fe in this
layer was confirmed through EDS analysis, which
revealed the composition of the materials in the
sample. The results show that the coating consists of
45.06% Oxygen (O), 48.14% Titanium (Ti), and 6.8%
Iron (Fe). This analysis provides a better understanding
of the structure and composition of the TiO2-Fe layer,
which plays an important role in improving solar cell
performance.
Efficiency Measurement
Performance
measurements
of
SubstanceSensitized Solar Cells (DSSCs) are carried out using
careful methods to ensure accurate results.
Researchers used a 24-watt UV lamp as a stable light
source, replacing direct sunlight whose intensity can
fluctuate. A multimeter was used to measure voltage
and current, while a 100K potentiometer was used to
measure electrical power. The efficiency of the solar
cell was determined by calculating the maximum
power point (MPP) from the I-V curve and fill factor (FF).
The values of Voc, Isc, Jsc, FF, and efficiency in
Table 3 were obtained from the I-V curves shown in
Figure 8. These values were extracted using Equations
(1)–(3), where Voc is determined as the x-intercept of
the curve, and Isc as the y-intercept. The fill factor (FF)
and efficiency were calculated based on the maximum
power point (Vmp, Imp) derived from the I-V
characteristics. To enhance clarity, we have labeled key
parameters in Figure 8, highlighting Voc and Isc values
for each condition.
The results showed an increase in DSSC efficiency
from 1.189% without Fe coating to 1.700% with the
addition of Fe coating. This Fe layer plays a role in
reducing electron recombination, thus increasing the
efficiency of solar cells. In addition, the smaller TiO2
crystal size also contributes to the increase in efficiency
as it provides a larger surface area to absorb the dye.
Although there is an improvement, this increase in
efficiency is not very significant. Further analysis
revealed that the amount of Fe attached to the TiO2
surface was very small and uneven, forming incoherent
clumps. This results in less than optimal protection
against electron recombination. In conclusion, the
addition of the Fe layer did increase the efficiency of
the DSSC, but there is still room for improvement in the
manufacturing process to achieve more optimal
results. The electrical properties of the DSSC were also
measured after the addition of anthocyanin dyes from
various natural sources. The results obtained are
shown in Figure 9.

This study revealed that the combination of TiO2-Fe
with various dye copigments produced DSSCs with
diverse performance. The DSSC efficiencies of the
different dye sources showed significant variations,
with jengkol skin producing the lowest efficiency of
1.925%, followed by grape skin (2.569%), senduduk
fruit (3.495%), and mangosteen skin achieving the
highest efficiency of 4.123%. The superiority of
mangosteen peel can be explained by several key
factors. First, copigmentation with salicylic acid
increases the absorbance and absorbance intensity of
the dye. Second, the maximum wavelength of
mangosteen peel at 515 nm indicates that the
anthocyanin-salicylic acid complex requires relatively
low energy to excite electrons. This process begins
when electrons are excited from the conduction band
to the valence band in the mangosteen peel extract,
then flow to TiO2. This low excitation energy allows for
more efficient electron transfer from the dye to the TiO2
and the outer circuit of the DSSC, ultimately improving
the overall performance of the solar cell. These results
demonstrate the significant potential of mangosteen
peel as an effective natural dye source for DSSC
applications, especially when combined with
copigmentation techniques using salicylic acid.
CONCLUSIONS
This study demonstrates the potential of Fe
electrodeposition on TiO₂ combined with pigmented
natural dyes to enhance the efficiency of dye-sensitized
solar cells (DSSCs). The copigmentation of
anthocyanins with salicylic acid was found to improve
thermal stability by forming hydrogen bonds and metal
complexes that reduce degradation. Furthermore, this
copigmentation induces a bathochromic effect, shifting
the absorption towards longer wavelengths due to
changes in the electronic environment of anthocyanins.
Electrodeposition of Fe on the TiO₂ layer reduces
electron recombination, enhancing DSSC efficiency.
The combination of TiO₂-Fe layers with pigmented
dyes resulted in varied DSSC performances, with
mangosteen peel showing the highest efficiency
(4.123%), followed by senduduk fruit (3.495%), grape
peel (2.569%), and jengkol peel (1.925%). The
superior performance of mangosteen peel is attributed
to its high anthocyanin content, particularly cyanidin
and delphinidin, which have extensive conjugation and
strong light absorption in the DSSC wavelength range.
The increase in efficiency from 1.189% (without Fe
coating) to 1.700% (with Fe coating) highlights the
potential of this approach. Additionally, the small TiO₂
crystal size (61.8 nm) enhances the surface area,
improving dye adsorption and solar cell performance.
These findings suggest that Fe electrodeposition on
TiO₂, combined with anthocyanin-rich natural dyes
(particularly from mangosteen peel), presents a
promising strategy for developing more efficient and
sustainable DSSCs.

357

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