J. Nig. Soc. Phys. Sci. 3 (2021) 287–291

Journal of the
Nigerian Society

of Physical
Sciences

Fabrication and Characterization of a Dye-Sensitized Solar Cell
using Natural Dye Extract of Rosella (Hibiscus sabdariffa L.) as

Photosensitizer

A. A. Willoughbya, A. O. Sogea,∗, O. F. Dairoa, O. D. Olukannib, E. U. Durugboc, W. S. Michaela, T.
A. Adebayod

aRedeemer’s University, Faculty of Natural Science, Department of Physical Sciences, Gbongan-Osogbo Expressway, Akoda Ede, Osun State, Nigeria, 232102
bRedeemer’s University, Faculty of Basic Medical Sciences, Department of Biochemistry, Gbongan-Osogbo Expressway, Akoda Ede, Osun State, Nigeria, 232102
cRedeemer’s University, Faculty of Natural Science, Department of Biological Sciences, Gbongan-Osogbo Expressway, Akoda Ede, Osun State, Nigeria, 232102
dRedeemer’s University, Faculty of Natural Science, Department of Chemical Sciences, Gbongan-Osogbo Expressway, Akoda Ede, Osun State, Nigeria, 232102

Abstract

The relatively low energy conversion efficiency of dye-sensitized solar cells (DSSCs) is a key challenge hindering the commercialization of the
solar cell. The photochemical performance of the dye used as a photosensitizer for the DSSC greatly determines the efficiency of the solar cell.
This study demonstrates the suitability of dye extracted from rosella (Hibiscus sabdariffa L.) flowers as a photosensitizer for a DSSC. The natural
dye was extracted using the acid water extraction method and was characterized using FTIR spectroscopy and UV–vis spectrophotometry.The
absorption spectra of the dye were examined to determine the aptness of the dye as a photosensitizer inDSSCs. The IR absorption spectra of
the extracted dye confirmed both amine and hydroxyl compounds as functional groups in the natural dye, which established the suitability of the
dye as a photosensitizer in DSSCs.The UV-vis absorption spectra of the natural dye within the visible region illustrate that the aqueous extract
from rosella flowers has stable absorption of visible light, thus validating the natural dye as a good candidate for photosensitizer in a DSSC. The
fabricated DSSC delivered a short-circuit current of 5 µA and an open-circuit voltage of 0.637 V.

DOI:10.46481/jnsps.2021.346

Keywords: dye-sensitized solar cells, rosella flowers, natural dye, energy conversion efficiency, photosensitizers, absorption spectra

Article History :
Received: 13 August 2021
Received in revised form: 24 September 2021
Accepted for publication: 25 September 2021
Published: 29 November 2021

c©2021 Journal of the Nigerian Society of Physical Sciences. All rights reserved.
Communicated by: E. Etim

1. Introduction

Renewable energy sources can meet the growing energy de-
mand and are poised to supply the world with a reliable, envi-
ronmentally friendly, and sustainable energy system [1]. Dye-
sensitized solar cells (DSSCs), being a type of photovoltaic

∗Corresponding author tel. no: +2347069381694
Email address: sogea@run.edu.ng, ayosoge@gmail.com (A. O.

Soge )

(PV) device, have gained widespread attention in recent years
due to their comparative advantages over silicon PV cells –
easy fabrication procedures, low manufacturing cost, and com-
patibility with flexible substrates [2]. Besides, DSSCs have a
high potential for industrial-scale manufacturing due to their
production using established scalable manufacturing methods
[3, 4, 5, 6, 7]. Additionally, DSSCs display higher performance
under low- and indoor-light conditions than the other PV tech-
nologies [8]. The expanded option of designing DSSCs using

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A. A. Willoughby et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 287–291 288

various materials coupled with flexibility in shape, colours, and
transparency, has qualified DSSCs for potential applications in
PV windows and textiles [5, 9, 10].

The low photoelectric conversion efficiency and instability
of the solar cells have been identified as the major challenges
impeding the commercialization of DSSCs [8]. Although the
highest theoretical efficiency for DSSCs has been calculated to
be 32% [11], the maximum efficiency reported in the literature
is about 14.3% as measured by Kakiage et al. in 2015 [12].

The authors utilized carboxy-anchor organic dye (LEG4)
and alkoxysilyl-anchor dye (ADEKA-1) as co-sensitizers for
the photoelectrodes together with a cobalt-based electrolyte in
fabricating the devices [12]. Extensive research is being un-
dertaken to investigate the factors that regulate the performance
of DSSC to ultimately enhance its efficiency [2]. For instance,
research interests in this field have focussed on optimizing the
redox couple [13] and dye absorbance [14], modifying semi-
conductors with a wide band-gap as photo-electrodes [15, 16]
and developing high-performance counter-electrodes [17].

Moreover, natural and commercial synthetic dyes have been
reported as a good replacement for transition metal coordina-
tion compounds (rutheniumpolypyridyl complexes) which are
regarded as effective sensitizers but contain a costly heavy metal
that posed environmental challenges [18]. Besides, the process
of synthesizing the complexes is complicated and expensive
[19]. The advantages of natural dyes include their abundance
in nature, environmental friendliness, and affordability.On the
other hand, synthetic organic dyes, such as coumarin, xanthene,
phthalocyanine, and cyanine dyes exhibit poor performance in
DSSCs owing to weak anchorage with TiO2 film and low UV-
vis absorption capability [2]. However, these synthetic organic
dyes are inexpensive and easy to prepare [20].

The energy conversion efficiency of a DSSC is determined
mainly by the absorption spectrum of the dye couple with its
anchorage to the TiO2 surface [21]. Hence, the dye used as a
sensitizer in a DSSC plays a prominent role in the performance
of the solar cell [19]. To improve the performance of DSSCs
with natural dye as a sensitizer, several researchers have inves-
tigated a wide variety of plants, fruits, and flowers to determine
their effectiveness as sensitizers in DSSCs. For instance, Sud-
hakaret et al. [22] fabricated DSSCs using extracted dye from
Bauhinia purpurea L. flower as a sensitizer. According to the
experimental results, the as-prepared solar cells delivered a con-
version efficiency of 0.63%, with an open-circuit voltage of 0.7
V, short-circuit current density of 1.4mA/cm2,and a fill factor
of 0.64%.

Reda et al. [23] investigated anthocyanin extracts from mul-
berry (Morus alba L.) fruit and Akenchira (Striga hermonth-
ica(Delile) Benth.) flower as natural photosensitizers with a
TiO2 semiconductor. Anthocyanin raw pigments extracted from
M. alba fruits and S. hermonthicaflowers under acidic condi-
tions delivered incident photon to current conversion efficien-

cies (IPCEs) greater than 15%. However, both the IPCEs and
solar energy conversion efficiency of the DSSCs were enhanced
using acidified ethanol for dye extraction. The IPCEs obtained
for the dye extracted from M. alba and S. hermonthica were
27% and 17%, respectively, while conversion efficiencies of the
DSSCs fabricated using dyes extracted from M. alba and S. her-
monthica were 0.420% and 0.304%, respectively.

Abdou et al. [19] compared the performance of DSSCs fab-
ricated using three different dyes as photosensitizers - rosella
(Hibiscus sabdariffa L.) flowers, Remazole Red RB-133,and
merocyanin-like dye-based on 7-methyl coumarin. The high-
est conversion efficiency of 0.27% was obtained with the natu-
ral dye extracted from rosella flowers. Remazole Red RB-133
and merocyanin-like dye delivered lower conversion efficien-
cies of 0.14% and 0.001%, respectively. Additionally, Senthil
et al. [24] investigated the photochemical characteristics of
two natural dyes extracted from Eugenia jambolana L. and De-
lonix regia and reported efficiencies of 0.55% and 0.317 %,
respectively. In a similar study, Chang and Lo [25] prepared
DSSCs using dyes extracted from pomegranate leaves and mul-
berry fruits as photosensitizers. The DSSCs fabricated with the
dye mixture delivered the best conversion efficiency of 0.722%
while those of pomegranate leaves and mulberry fruits offered
relatively lower conversion efficiencies of 0.597% and 0.548%,
respectively.

Gomez-Ortiz et al. [26] prepared solar cells using TiO2
and ZnO nanostructured, mesoporous films sensitized with an-
natto, bixin, and norbixin dyes extracted from achiote seeds
(Bixaorellana L.). Best results were obtained for bixin-sensitized
TiO2 solar cell with conversion efficiency up to 0.53%. This
study investigates the performance of rosella (Hibiscus sabdar-
iffa L.) as a photosensitizer in a DSSC. Additionally, the IR
and UV-vis absorption spectra of the natural dye are examined
to validate the suitability of the dye as a photosensitizer in the
fabrication of a DSSC.

2. Materials and methods

Dye was extracted from rosella (H. sabdariffa) flowers (Fig-
ure 1) using the acid water (H2S O4 ) extraction method.

2.1. Preparation
The dye extract was prepared by grinding 12 g of dried

rosella flowers in 500 ml of acid water with pH = 5.7. The
extract was filtered and centrifuged separately to remove any
solid residue and stabilized at pH = 5.7 by adding an aqueous
solution of 0.1 M HCl. The half-time deactivation of the dye
solution was over 12 months provided they are correctly stored
at 4 ◦C in a refrigerator [27]. The natural dye extracted from
the rosella flowers was characterized using T60 UV-vis spec-
trophotometer (PG electronics, UK) by measuring their UV ab-
sorbance. Additionally, a Fourier transform infrared (FTIR)
spectroscopy analysis was carried out on the natural dye to
determine its chemical compositions using FTIR-8400S spec-
trophotometer (Shimadzu Scientific Instruments Inc., Japan).

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A. A. Willoughby et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 287–291 289

Figure 1: Rosella (H. sabdariffa) flowers .

The fabrication of DSSCs normally involves using materials
with properties that typically increase the performance and ef-
ficiency of the cells. This includes a porous film of nanocrys-
talline semiconductor such as titanium dioxide film, an elec-
trolyte, dye sensitizers, and conductive glasses as electrodes.

The electrolyte was prepared using 10 ml ethylene glycol,
0.127 g iodine, and 0.83 g potassium iodide. The electrolyte
solution was stirred thoroughly until no grains of iodine and
potassium iodide were visible. The photo-anode comprising
fluorine-doped tin oxide glass substrates annealed with a porous
TiO2 was synthesized by absorbing a small amount of the dye
extract on the TiO2 layer. The electrode was left for about 10
minutes for complete absorption of the dye, then rinsed first us-
ing deionized water and then a final rinse with ethanol (which
acts as a drying agent to remove any present water). Afterward,
the film was dried in an oven at 60 ◦C for 5 minutes. With this
approach, the dye extends the photoanode’s spectral sensitivity,
thereby enabling the collection of lower energy photons. The
counter-electrode (or cathode) was prepared by coating the con-
ductive side of the fluorine-doped tin oxide glass with graphite
after wiping the surface with ethanol. The DSSC was assem-
bled by placing the TiO2-coated anode facing upward, and the
conductive side of the graphite-coated cathode faced the TiO2
film. The electrodes were positioned slightly offset to allow
enough space for electrical contacts and were held together us-
ing binder clips, as shown in Figure 2. The electrolyte was
introduced into the space between the electrodes by capillary
action.

The open-circuit voltage and short-circuit current of the fab-
ricated DSSCs were determined under a laboratory condition
using a multimeter with a flash lamp (CTL – RL020) with an
intensity less than 100 mW/cm2 illumination.

3. Results and discussion

The FTIR result showing the infrared (IR) spectra of the
extracted dye from rosella flowers is presented in Figure 3. A
broad absorption typical of the hydroxyl group was observed at

Figure 2: Assembled dye-sensitized solar cells showing the electrodes being
held together with binder clips.

3421.83 nm for the natural dye. The second absorption band
was detected at 2359.02 nm (Figure 3). This relatively nar-
row absorption is attributed to the C-H stretch of a terminal
alkyne or acetylenic compound. Additionally, the prominent
absorption band for the dye at ∼ 3430 nm is broad and indi-
cates the presence of hydroxyl and N-H amine/amide groups.
Furthermore, the results show the presence of amide I (1600–
1800 cm−1) and amide II (1470–1570 cm−1) groups. Amide I
groups are products of C-O bonds while amide II groups are
associated with N-H bending typically of amino acids. Amino
acids are protein constituent which functional groups readily
increase electron transfer process in DSSC layer. They achieve
this by acting as acids in strong bases (donating protons) and
as bases (accepting protons from strong acids) [28]. Thus, the
IR spectra of the extracted dye confirmed the presence of amine
and hydroxyl groups in the natural dye which implies that the
dye is a suitable photosensitizer for DSSCs.

Figure 3: Infra-red spectra of the extracted dye from rosella (H. Sabdariffa)
flowers showing the IR transmission percentage (%T) versus wavelength in nm.

The UV-vis absorption spectra for the aqueous extract of
rosella (H. Sabdariffa) flowers are illustrated in Figure 4.

Absorbance is a measure of UV light absorbed by the dye.
The higher the value, the more a particular wavelength is be-
ing absorbed. Many organic compounds undergo electronic

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A. A. Willoughby et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 287–291 290

Figure 4: UV-vis absorption spectra of rosella (H. sabdariffa) flowers .

changes owing to shorter wavelengths and higher energy radia-
tion in the UV (200-400 nm) and visible (380-800 nm) ranges
of the electromagnetic spectrum [29]. The purple colour of the
dye extracted from rosella flowers (H. Sabdariffa) could be at-
tributed to both the absorption peak at 520 nm lying within the
green-cyan region (500 – 565 nm) and the absorption peaks at
230 and 290 nm falling within the UV region (200 – 400 nm).
The UV-vis absorption spectra of the natural dye within the vis-
ible region (380 – 800 nm) illustrates that the aqueous extract
from rosella flowers has stable absorption of visible light, im-
plying that the dye is a good candidate for photosensitizer in
DSSCs.

Moreover, the fabricated DSSC with the natural dye ex-
tracted from rosella flowers as a photosensitizer, demonstrated
promising photoelectrochemical performances delivering short-
circuit current of 5 µA and an open-circuit voltage of 0.637 V
using a liquid-state electrolyte composed of PEO-ethylene gly-
col, iodine, potassium iodide blend.

4. Conclusion

This work reports an investigation on the suitability of the
natural dye extracted from rosella (H. sabdariffa) flowers as a
photosensitizer in a DSSC. The IR spectra of the extracted dye
confirmed both amine and hydroxyl groups in the natural dye
suggesting that the dye is a suitable photosensitizer for DSSCs.
The UV-vis absorption spectra of the natural dye within the vis-
ible region (380 – 800 nm) demonstrate that the dye extracted
from rosella flowers has stable absorption of visible light, indi-
cating that the natural dye is a good candidate for photosensi-
tizer in a DSSC. The fabricated DSSC with the aqueous extract
of rosella flowers as photosensitizer displayed promising pho-
toelectrochemical performances delivering short-circuit current
of 5 µA and an open-circuit voltage of 0.637 V.

References

[1] M. S. Su’ait, M. Y. A. Rahman & A. Ahmad, “Review on polymer elec-
trolyte in dye-sensitized solar cells (DSSCs)”, Solar Energy 115 (2015)
452.

[2] S. Mozaffari, M. R. Nateghi & M. B. Zarandi, “An overview of the Chal-
lenges in the commercialization of dye sensitized solar cells”, Renewable
and Sustainable Energy Reviews 71 (2017) 675.

[3] H. Iftikhar, G. G. Sonai, S. G. Hashmi, A. F. Nogueira & P. D. Lund,
“Progress on electrolytes development in dye-sensitized solar cells”, Ma-
terials 12 (2019) 1998.

[4] F. Bittner, T. Oekermann & M. Wark, “Scale-up of the electrodeposi-
tion of ZnO/Eosin Y hybrid thin films for the fabrication of flexible dye-
sensitized solar cell modules”, Materials 11 (2018) 232.

[5] I. Juhász Junger, D. Wehlage, R. Böttjer, T. Grothe, L. Juhász, C. Grass-
mann, T. Blachowicz & A. Ehrmann, “Dye-sensitized solar cells with
electrospun nanofiber mat-based counter electrodes”, Materials 11 (2018)
604.

[6] S. Hashmi, D. Martineau, X. Li, M. Ozkan, A. Tiihonen, M. Dar, T.
Sarikka, S. Zakeeruddin, J. Paltakari, P. Lund and et al., “Air Processed
Inkjet Infiltrated Carbon Based Printed Perovskite Solar Cells with High
Stability and Reproducibility”, Adv. Mater. Technol. 2 (2017) 1600183.

[7] S. Hashmi, M. Ozkan, J. Halme, K. Misic, S. Zakeeruddin, J. Paltakari,
M. Grätzel & P. Lund, “High performance dye-sensitized solar cells with
inkjet printed ionic liquid electrolyte”, Nano Energy 17 (2015) 206.

[8] A. Fakharuddin, R. Jose, T. M. Brown, F. Fabregat-Santiago & J. Bis-
quert, “A perspective on the production of dye-sensitized solar modules”,
Energy & Environmental Science 7 (2014) 3952.

[9] D. S. Lim, K. W. Park, A. A. Wiles & J. Hong, “Metal-free organic chro-
mophores featuring an ethynyl-thienothiophene linker with an n-hexyl
chain for translucent dye-sensitized solar cells”, Materials 12 (2019)
1741.

[10] A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo & H. Pettersson, “Dye-
sensitized solar cells”, Chemical reviews 110 (2010) 6595.

[11] H. J. Snaith, “Estimating the maximum attainable efficiency in dye-
sensitized solar cells”, Adv. Funct. Mater. 20 (2010) 13.

[12] K. Kakiage, Y. Aoyama, T. Yano, K. Oya, J. I. Fujisawa & M. Hanaya,
“Highly-efficient dye-sensitized solar cells with collaborative sensitiza-
tion by silyl-anchor and carboxy-anchor dyes”, Chemical communica-
tions 51 (2015) 15894.

[13] J. Wu, Z. Lan, J. Lin, M. Huang, Y. Huang, L. Fan & G. Luo, “Electrolytes
in dye-sensitized solar cells”, Chemical reviews 115 (2015) 2136.

[14] B. Sebo, N. Huang, Y. Liu, Q. Tai, L. Liang, H. Hu, S. Xu & X. Z. Zhao,
“Dye-sensitized solar cells enhanced by optical absorption, mediated by
TiO2 nanofibers and plasmonics Ag nanoparticles”, Electrochimica Acta
112 (2013) 458.

[15] J. Macaira, L. Andrade & A. Mendes, “Review on nanostructured photo-
electrodes for next generation dye-sensitized solar cells”, Renewable and
Sustainable Energy Review 27 (2013) 334.

[16] R. C. C. & R. Prasanth, “A critical review of recent developments in nano-
materials for photoelectrodes in dye sensitized solar cells”, Journal of
Power Sources 317 (2016) 120.

[17] M. Wu & T. Ma, “Platinum-free catalysts as counter electrodes in dye-
sensitized solar cells”, Chem. Sus. Chem. 5 (2012) 1343.

[18] Y. Amao & T. Komori, “Bio-photovoltaic conversion device using
chlorine-e6 derived from chlorophyll from Spirulina adsorbed on a
nanocrystalline TiO2 film electrode”, Biosensors and Bioelectronics 19
(2004) 843.

[19] E. M. Abdou, H. S. Hafez, E. Bakir & M. S. A. Abdel-Mottaleb, “Photo-
stability of low cost dye-sensitized solar cells based on natural and syn-
thetic dyes”, Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy 115 (2013) 202.

[20] S. Hao, J. Wu, Y. Huang & J. Lin, “Natural dyes as photosensitizers for
dye-sensitized solar cell”, Solar energy 80 (2006) 209.

[21] K. Tennakone, G. Kumara, A. Kumarasinghe, P. Sirimanne & K. Wi-
jayantha, “Efficient photosensitization of nanocrystalline TiO2 films by
tannins and related phenolic substances”, J. Photoch. Photobio. 94 (1996)
A94.

[22] C. Sudhakar, T. Selvankumar, K. Selvam & M. Govindaraju, “Bauhinia
purpurea L. flower mediated dye used as sensitizers for TiO2 based dye-
sensitized solar cells”, International Journal on Advanced Science, Engi-
neering 2 (2016) 209.

[23] A. Reda, S. Tadesse & T. Yohannes, “Dye-sensitized solar cell using nat-
ural dyes extracted from Morus atba Lam fruit and Striga hermonthica
flower”, Journal of Photonics for Energy 4 (2014) 043091.

[24] T. S. Senthil, M. Thambidurai, N. Muthukumarasamy, R. Balasundara-

290



A. A. Willoughby et al. / J. Nig. Soc. Phys. Sci. 3 (2021) 287–291 291

prabhu & S. Agilan, “Preparation and Characterization of Sol-Gel Spin
Coated Nanocrystalline TiO2 Films”, Advanced Science Letters 4 (2011)
3649.

[25] H. Chang & Y. J. Lo, “Pomegranate leaves and mulberry fruit as natural
sensitizers for dye-sensitized solar cells”, Solar energy 84 (2010) 1833.

[26] N. M. Gómez-Ortı́z, I. A. Vázquez-Maldonado, A. R. Pérez-Espadas, G.
J. Mena-Rejón, J. A. Azamar-Barrios & G. Oskam, “Dye-sensitized so-
lar cells with natural dyes extracted from achiote seeds”, Solar Energy
Materials and Solar Cells 94 (2010) 40.

[27] A. R. Hernandez-Martinez, M. Estevez, S. Vargas, F. Quintanilla & R. Ro-
driguez, “New dye-sensitized solar cells obtained from extracted bracts of

Bougainvillea glabra and spectabilis betalain pigments by different purifi-
cation processes”, International journal of molecular sciences 12 (2011)
5565.

[28] P. Trihutomo, S. Soeparman, D. Widhiyanuriyawan & L. Yuliati, “Per-
formance improvement of dye-sensitized solar cell-(DSSC-) based natu-
ral dyes by clathrin protein”, International Journal of Photoenergy 2019
(2019) 1.

[29] Excited Electronic States: Electronic Spectroscopy of Molecules (3rd
February 2016). https://chem.libretexts.org/@go/page/44497 (Accessed
on 13th September 2021).

291