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POTENTIAL APPLICATION OF BIS-CHALCONE IN PLASTIC SUBSTRATE SOLAR
CELL DEVICE
Wee Hung Yee (39316)
Bachelor of Science with Honours
(Resource Chemistry)
2015
Faculty of Resource Science and Technology
Potential Application of Bis-chalcone in Plastic Substrate Solar Cell Device
Wee Hung Yee (39316)
A dissertation submitted in partial fulfilment of the requirement for
the degree of Bachelor of Science (Hons.)
Supervisor: Dr. Tay Meng Guan
RESOURCE CHEMISTRY PROGRAM (WS48)
DEPARTMENT OF CHEMISTRY
FACULTY OF RESOURCE SCIENCE AND TECHNOLOGY
UNIVERSITY MALAYSIA SARAWAK
20th
April 2015
I
Acknowledgements
I would like to thank to my supervisor, Dr Tay Meng Guan for his guidance and support so that I
can complete my research project. Furthermore, I would like to thank to the postgraduate
students, which are Ms. Chia Ying Ying, Ms. Suzie Kuan, Mr. Ong Kok Tong and Mr. Teo Kien
Yung for their willingness to share their knowledge, techniques and give comments and
suggestions to me. Besides, I would like to thank to all my friends who contributed a lot upon
completion of this project.
II
Declaration
I declare that the work in this thesis was carried out in accordance with the regulations of
Universiti Malaysia Sarawak. It is original and is the result of my work, unless otherwise
indicated or acknowledged as referenced work. This thesis has not been submitted at this or any
other university or academic institution for any other degree or qualification.
____________________________
Wee Hung Yee
Program of Resource Chemistry
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
III
Table of Contents
Acknowledgement…………………………………………………………....…………... I
Declaration………………………………………………………....…………................... II
Table of Contents………………………………………………………………....………. III
List of Abbreviation………………………………………………………….…...………. VII
List of Figures…………………………………………………………...……..…………. X
List of Scheme……………………………………………………….…….………........... XII
List of Table………………………………………………………………………………. XIII
Abstract…………….………………………………………...……………………............ XIV
1.0 Introduction…………………………………………………...……..….………......... 1
1.1 Harvesting energy from light...…………………………………………...…... 2
1.2 Chalcone compounds……………………………………………….....……… 4
1.3 Photovoltaic solar cells…………………………………………………….…. 7
1.3.1 Development history of photovoltaic cells………………………….. 10
1.3.1.1 First generation solar cells……………………………….….. 10
1.3.1.2 Second generation solar cells………………………………... 10
1.3.1.3 Third generation solar cells……………………………….…. 11
1.3.1.3.1 Plastic solar cells……………………….…..… 12
1.3.1.3.2 Dye-sensitized solar cells………….……..…… 12
1.3.1.4 Fourth generation solar cells……………….……………....... 13
1.3.2 Thin-film photovoltaic solar cell……………………….……………. 13
1.4 Problem statement……………………………………………………...……... 14
1.5 Objectives……………………………………….…………...………………... 15
IV
2.0 Literature Review…………………………………………………………..….…..... 16
2.1 Synthesis of chalcone…………………………………………………………. 16
2.1.1 Claisen-Schmidt condensation ………………………………………... 17
2.1.1.1 Base catalytic………………………………………................. 17
2.1.1.2 Acid catalytic…………………………………………………... 18
2.1.2 Suzuki method………………………………………………………. 20
2.1.3 Solvent-free grinding technique…………………………………….. 21
2.2 Bis-chalcone synthesis…………………………………………..................... 23
2.3 Photoinduced electron transfer in chalcone…………………………………... 26
2.4 Uses of chalcone compounds in solar cells…………………………………... 26
2.5 Efficiency enhancement of Dye-Sensitized Solar Cell (DSSC)…..………….. 27
2.5.1 Kinetic dynamic of DSSC………………………………………………. 28
2.5.2 Enhancement through metal oxides…………………………………….. 30
2.5.3 Selection of dyes………………………………………………………... 33
2.5.4 Mediator additive……………………………………………………….. 34
3.0 Methodology……………………………………………………..…………...…........ 36
3.1 Chemicals and reagents…………...…………………………………………... 36
3.1.1 Purification of ethanol.…………………………………………............ 36
3.2 Characterization…………………………………….………………………… 37
3.3 Synthesis of 1,4-bis[2-(2-hydroxybenzoyl)vinyl]benzene (1)….……..…..…. 37
3.4 Preparation of conductive plastic substrate……………………………….….. 38
3.5 Titanium (IV) oxide (TiO2) coating techniques………………………………. 38
3.5.1 Rolling TiO2 paste………………………………………………………. 38
3.5.2 Spin coating technique for conductive glass and aluminium foil…...….. 39
V
3.6 Preparation of KI3…………………………………………………………….. 39
3.7 Photovoltaic cell fabrication…………………………………….……………. 39
3.7.1 Fabrication of Dye-Sensitized Solar Cell……………………………….. 39
3.7.2 Fabrication of plastic solar cell…………………………………………. 40
3.8 Efficiency measurement and calculation……………………………………... 40
4.0 Results and Discussion………………………………………..…………………....... 41
4.1 Synthesis and characterization of 1,4-bis[2-(2-hydroxybenzoyl)vinyl]
benzene (1)……………………………………………………………..……..
41
4.1.1 Spectroscopy analysis……………………………………………...…… 42
4.1.1.1 IR analysis………………………………….…………………... 42
4.1.1.2 NMR analysis………………………………………….……….. 45
4.2 Characterization and testing of glass substrate solar cell (DSSC)…………… 48
4.2.1 SEM analysis…………..………………………………………………. 48
4.2.2 Conversion efficiency of solar cell……………………..……………… 49
4.3 Chemical deposition, characterization and testing of plastic substrate solar
cell…………………………………………………….……………………...
52
4.3.1 Chemical deposition on plastic (PET) substrate.................................... 52
4.3.2 Concentration effect of coating material towards the properties of PET
substrate……………….……………………………….……………...
54
4.3.3 Efficiency of plastic substrate solar cell……………………….…….. 56
5.0 Conclusion…………………………………………………………………………..... 59
6.0 Suggestion for future work………………………………………………………….. 60
VII
List of Abbreviation
AlCl3 Aluminium chloride
Ba(OH)2 Barium hydroxide
CdS Cadmium sulfide
CdTe Cadmium telluride
CH3OH Methanol
CHCl3 Trichloromethane
CIGS Copper indium gallium diselenide
CIS Copper indium selenide
Cl-
Chloride ion
Cs2CO3 Cesium carbonate
DCM Dichloromethane
DMF Dimethylformamide
DMSO Dimethylsufoxide
DSSC Dye-sensitized solar cell
Eg Energy band gap
VIII
FTIR Fourier transform infrared
H2O Water molecule
HCl Hydrochloric acid
I-
Iodide ion
I3 Triiodide ion
KBr Potassium bromide
KI3 Potassium triiodide
KOH Potassium hydroxide
MeCN Acetonitrile
Na2S2O3 Sodium thiosulfate
NaOH Sodium hydroxide
Ni Nickel
Ni(II)Cl2·6H2O Hexaaquanickel(II) chloride
NLO non-linear optics
NMR Nuclear magnetic resonance
OH-
Hydroxide ion
Pd(PPh3)4 Tetrakis(triphenylphosphine)palladium(0)
IX
PET Photoinduced electron transfer
Pt Platinum
Ru Ruthenium
SHG second harmonic generation
SOCl2 Thionyl chloride
STC Standard test condition
TCO Transparent conducting oxide
THF Tetrahydrofuran
TiCl4 Titanium chloride
TiO2 Titanium dioxide
TLC Thin layer chromatography
UV-Vis Ultraviolet-visible
X
List of Figures
Figure Title Page
1.1 Wavelength of light 2
1.2 Structure of chalcone 4
1.3 (a) cis-chalcone; (b) trans-chalcone 5
1.4 Second harmonic generation principle 6
1.5 3-(4-methoxyphenyl)-1-(4-pyrrol-1-yl-phenyl) prop-2-en-1-one 7
1.6 p-n junction 8
1.7 (a) Energy level of conduction band and valence band and (b) Formation of positive-
charged hole
9
1.8 Electrons and holes movement drifted by the action of electric field 9
1.9 Structure of second generation solar cells 11
1.10 Basic components in third generation solar cells 11
1.11 Plastic solar cells 12
1.12 Structure of dye-sensitized solar cells (DSSC) 13
2.1 Borondifluoride complexes of 2‟-hydroxychalcones 27
XI
2.2 Electron transfer between components in DSSC 28
2.3 Energy level of TiO2, LUMO and HOMO 29
2.4 Conduction band and valence band of TiO2 and coated metal oxide 31
2.5 Conduction band and valence band of TiO2 and coated metal oxide 32
2.6 Organic dye 33
4.1 Structure of synthesized bis-chalcone 41
4.2 IR spectrum of compound 1 44
4.3 Intramolecular hydrogen bonding 43
4.4 NMR spectrum of compound 1 47
4.5 Hydrogen in bis-chalcone 45
4.6 (a) Hand-coated conductive glass under SEM (200 magnification); (b) Hand-coated
conductive glass under SEM (20000 magnification)
49
4.7 (a) Spin coated conductive glass under SEM (200 magnification); (b) Spin coated
conductive glass under SEM (20000 magnification)
49
4.8 Surface of CuS coated PET under SEM 53
4.9 PET substrate coated with (a) 0.10 M, (b) 0.05 M and (c) 0.01 M concentration
solution; (d) comparison between 0.01 and 0.05 M (0.01 M at left and 0.05 M at right)
55
XII
List of Scheme
Scheme Title Page
2.1 Synthesis pathway of chalcone through base catalytic reaction 18
2.2 Synthesis pathway of chalcone through acid catalytic reaction 20
2.3 Coupling between phenylboronic acids and cinnamoyl chlorides 21
2.4 Coupling between phenylvinylboronic acids and benzoyl chlorides 21
2.5 Reaction between acetophenones and benzaldehydes 22
2.6 Synthesis of bis-chalcones 24
2.7 (a) Conventional and (b) Microwave-assisted synthesis of bis-chalcone 25
XIII
List of table
Table Title Page
4.1 Efficiency of glass substrate solar cells with two different coating methods 50
4.2 Surface resistance of PET in different concentration solution 54
4.3 Efficiency of plastics substrate solar cells with three different concentration 56
XIV
Potential Application of Bis-chalcone in Plastic Substrate Solar Cell Device
Wee Hung Yee
Resource Chemistry
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
Abstract
Due to depletion of petroleum, global is seeking for renewable energy to replace the conventional energy. In this
study, plastic solar cell was developed by using bis-chalcone (1,4-bis[2-(2-hydroxybenzoyl)vinyl]benzene) as a dye.
Bis-chalcone was successfully synthesized by base-catalytic Claisen-Schmidt condensation between 2-
hydroxyacetophenone and terephthalaldehyde. The synthesized bis-chalcone was characterized using FTIR and
NMR spectroscopy. After that, bis-chalcones were coated on spin coated and hand coated TiO2 which show 3.601 x
10-3
% and 2.439 x 10-3
% of efficiency respectively. Besides, CuS was successfully coated on plastic substrate by
using chemical bath deposition and the resistance per cm square of plastics substrate showed 74.6, 31.1 and 12.5 Ω
cm-2
when 0.01, 0.05 and 0.10 M of precursors were used respectively. Apart from that, plastics substrate solar cells
were fabricated based on 0.01, 0.05 and 0.10 M of concentration which showed 1.503 x 10-3
, 6.269 x 10-4
and 1.575
x 10-3
% of efficiency respectively. It is found that the 0.10 M against the theoretical hypothesis, which caused by a
few factors included the improvement of plastics substrate conductivity, the properties of CuS and thermal barrier of
bis-chalcone compound.
Keyword: Claisen-Schmidt condensation, bis-chalcone, plastic solar cell
Abstrak
Disebabkan petroluem yang semakin berkurangan, seluruh dunia sedang mengkaji tenaga yang dapat diperbaharui
untuk mengganti tenaga asli. Dalam kajian ini, sel suria plastik telah diperkembangkan dengan menggunakan bis-
chalcone (1,4-bis[2-(2-hydroxybenzoyl)vinyl]benzene) sebagai pencelup. Bis-chalcone telah berjaya dihasilkan
secara sintesis dengan menggunakan dasar pemangkin Claisen-Schmidt pemeluwapan antara 2-
hydroxyacetophenone dan terephthalaldehyde. Bis-chalcone yang disintesis mengambarkan sifatnya dengan
menggunakan FTIR dan NMR spektroskopi. Selepas itu, bis-chalcones telah diselaputi atas penyelaput pusing dan
penyelaput secara tangan TiO2, ia menunjukkan efisien 3.601 x 10-3
% dan 2.439 x 10-3
% masing-masing. Selain itu,
CuS telah berjaya diselaputi atas plastik substrat dengan menggunakan mandian pemendapan kimia dan rintangan
untuk plastik substrat bagi setiap empat persegi sentimeter adalah 74.6, 31.1 and 12.5 Ω cm-2
apabila 0.01, 0.05
dan 0.10 M perintis telah digunakan masing-masing. Di samping itu, sel-sel suria yang berplastik substrat telah
difabrik dengan perintis yang berpekatan 0.01, 0.05 dan 0.10 M dan menunjukkan 1.503 x 10-3
, 6.269 x 10-4
and
1.575 x 10-3
% effisiensi masing-masing. Kajian ini mendapati bahawa 0.10 M bertentangan dengan hipotesis dari
segi teori, ini boleh disebabkan oleh beberapa faktor, contohnya, pembaikan perihal pengaliran elektrik tentang
plastik substrat, sifat CuS dan terma penyekat tentang bis-chalcone campuran.
Kata Kunci: Claisen-Schmidt pemeluwapan, bis-chalcone, sel solar plastik
1
1.0 Introduction
Human are depending on energy to sustain their life. Fuel from fossil fuels was used in
transportation and generates electricity for our daily uses. However, fossil fuel is not a renewable
energy and might be used up in future. According to Muda and Tey (2012), Klass model
forecasted that all the fossil fuels will be used up in 2077. Due to the depletion of petroleum,
rising of fuels price and concerns with global warming when keep using fossil fuels as the
primary energy source, many countries are looking for other renewable energy such as solar
energy and hydro energy to replace fossil fuels. Renewable energy is generally defined as energy
from non-depletable resources or resources that can be naturally replenish. Solar energy is one of
the renewable energy that derived from sunlight. According to Smalley (2009), there is 3x1024
J
per year of energy supplied from the sun to the earth, which is 10000 times more than what
human uses. Therefore, it has the resource potential to become global energy demand as it is
widely distributed on Earth‟s surface and causes no pollution to environment. Thus, development
of solar cell that used to harvest solar energy has attracted a great attention in recent year.
The history of solar cell started in 1839 year when Becquerel observed that silver chloride coated
platinum electrode in an aqueous nitric acid electrolyte generated direct current when the
electrode is exposure under sunlight. Few decades later, Adams and Day (1876) observed that
the solid state of selenium is able to generate electric current when exposure by light. However,
due to the very low efficiency of conversion from solar energy to electrical energy, the electricity
generated is not enough to operate electrical equipment. After the law of photovoltaic effect was
discovered in 1905 by Einstein, Chapin and his coworkers developed the first silicon
photovoltaic cell at the Bell Telephone Laboratory, USA. The efficiency of energy conversion
2
for this photovoltaic cell achieved 6% (Bubenzer & Luther, 2003; Chapin et al., 1954;
Fahrenbruch & Bube, 1983). Due to this high percentage of efficiency in energy conversion, the
solar cells are able to generate enough electricity to operate electrical equipment. Besides, this
new invention also acts as power sources in the field of astronautics, especially for satellites.
However, these solar cells are only limited for the space applications, due to its high production
costs. The commercial solar age is officially begun in 1954. Today, solar cells that widely used
in the market, especially in microelectronic market are dominated by silicon type solar cell
(Goetzberger et al., 2002).
1.1 Harvesting energy from light
Light is a form of energy which travels in the form of wavelength (Figure 1.1). Different
wavelengths have different energy contents. The shorter the wavelength of light, the higher the
energy content is. When light travels, the energy (light energy) is carried by elementary particles
called photons. After the law of photovoltaic effect was discovery, scientists develop devices that
can harvest the energy from light, which is commonly known as solar cell.
Figure 1.1: Wavelength of light
The efficiency of energy conversion is defined as the ability to convert solar energy into usable
electricity. It is usually measured under standard test condition (STC). The STC refers to 1000
Wm-2
of sunlight irradiation and cell temperature of 25°C under air mass 1.5 (Arndt & Puto,
3
2011). It can be expressed in term of percentage as described by Equation 1.1 (Emery &
Osterwald, 1986):
η = Pmax x 100 % …………...………..Equation 1.1
A x ESTND
Where, η = conversion efficiency of solar cells under standard test condition
Pmax = maximum power produced by solar cell in unit of watt, W
A = total surface area of solar cells (including frame and borders) in the
unit of square meter, m2
ESTND = standard spectral irradiance, 1000 Wm-2
The maximum power cannot determine directly from the solar sell. It is determined by the
product of fill factor (FF), short circuit current (Isc) and open circuit voltage (Voc) of solar cell
(Equation 1.2).
Pmax = FF x Isc x Voc ……………………....Equation 1.2
The power of solar cell is obtained when the value for both of the short circuit current and open
circuit voltage is zero. Therefore, a term called “fill factor” is used as the parameter in
conjunction with short circuit current and open circuit voltage in order to determine the
maximum power of solar cell. Fill factor is defined as the ratio of maximum power from the sun
to the product of short circuit current and open circuit voltage (Castellano, 2010).
4
According to Green (1981), fill factor can be calculated by using Equation 1.3.
FF = Voc – In(Voc + 0.72)
………………….……...…..Equation 1.3 Voc + 1
By combining the Equation 1.1, Equation 1.2 and Equation 1.3, Equation 1.4 is formed. In
this study, Equation 1.4 is used to calculate the conversion efficiency.
Η = [Voc – In(Voc + 0.72)] x Isc x Voc
x 100 % ………..Equation 1.4 A x ESTND x [Voc + 1]
1.2 Chalcone compounds
Chalcone is a natural compound which can be found in apple seeds (Marcus et al., 2001). It is
also known as benzalacetophenone or benzylideneacetophenone with the IUPAC name of 1,3-
diphenyl-2-propen-1-one. The structure of chalcone (Figure 1.2) consists of two aromatic rings
that linked by ,-keto-enol containing group.
Figure 1.2: Structure of chalcone
Chalcone can exist either in cis- or trans- conformation (Figure 1.3) as the conjugated C-C
double bond is present in the structure. Trans-conformation of chalcone is more
5
thermodynamically favoured in normal condition due to the conjugated -electron-system that
leads to a stable and planar structure (Muller, 2012).
(a) (b)
Figure 1.3: (a) cis-chalcone; (b) trans-chalcone
Chalcone and its derivatives are widely used in materials science fields such as non-linear optics
(NLO), optical computing, optical communication, optical limiting, photoinitiated
polymerization, electrochemical sensing and Langmuir films (Asiri & Khan, 2011; Asiri et al.
2013). Chalcones are used as NLO due to its good optical power limiting properties and third-
order nonlinearity (Kamath et al., 2014). They offer large nonlinear coefficients due to the fact
that they consist of a conjugated double bond in between two planar benzene rings. The
delocalization of -electrons within these double bond and benzene rings are the one that
responsible for the third order nonlinear optical responses (Poornesh et al., 2009). Furthermore,
the responses can be increased by enhancing the ability of electron donating groups.
Besides that, some of the chalcone compounds have second harmonic generation (SHG)
properties (Patil et al., 2007). SHG is a nonlinear optical process which a photon is produced
from two photons with same frequency and energy in a nonlinear material. The produced photon
6
has twice the frequency and amount of energy compared to the initial photons. Moreover, the
wavelengths of the produced photons are only half of their initial photons (Figure 1.4). This
nonlinear optical process allows the laser industry to make a stronger laser light. The incident
laser with lower energy, less intensity and longer wavelength is able to convert into a stronger
laser ray with higher energy, more intensity and shorter wavelength.
Energy level
Figure 1.4: Second harmonic generation principle
Chalcone and its derivatives also play an important role in biological field especially for
pharmalogical activities such as anti-bacterial, anti-malarial, anti-cancer, anti-microbial, anti-
oxidant and anti-inflammatory (Prasad et al., 2008; Rahman, 2011). According to Syam et al.
(2012), some chalcone derivative compounds such as 3-(4-Methoxyphenyl)-1-phenylpropenone
having anti-cancer activity due to their capacity to elicit apoptosis. 3-(4-methoxyphenyl)-1-(4-
pyrrol-1-yl-phenyl) prop-2-en-1-one (Figure 1.5), one of the chalcone derivative compound was
used in anti-malarial which shows about 50% of inhibition concentration of the parasites stain
(Awasthi et al., 2009). Besides, bis-pyrazoline that derived from bis-chalcone is used in anti-
Initial photon
Photon produced with
twice the energy Initial photon
7
bacterial activities. This compound is able to inhibit both Gram-positive and Gram-negative
bacteria (Asiri & Khan, 2011).
Figure 1.5: 3-(4-methoxyphenyl)-1-(4-pyrrol-1-yl-phenyl) prop-2-en-1-one
Due to the widely used of chalcone and its derivative compound, it is commonly synthesized
artificially rather than extract from plants. Claisen-Schmidt condensation reaction is one of the
common methods used in the synthesis of chalcone. Besides, microwave irradiation, ultrasound
irradiation, Suzuki reaction and solvent-free grinding technique are also used in the synthesis of
chalcone (Zangade et al., 2011).
1.3 Photovoltaic solar cells
Photovoltaic solar cell is part of solar power system that converts sunlight into electricity.
According to Saga (2010), there is about 90% of solar cells used in the market are made from
silicon, it is known as conventional solar cell and built up by two layers of semiconductor, which
are positive semiconductor (p-type) and negative semiconductor (n-type). Both p-type and n-type
semiconductor are produced by the doping of silicon and joining together to form a p-n junction
(Figure 1.6). When there is no current flow, a depletion layer is form in between the p-n junction.
When the equilibrium has been achieved, there are negative ions (free electrons) in the p-type
material and positive ions (empty holes) in the n-type material.