Progress in the Development of Polymeric Materials for Alternative Energy Devices
at PENTEC research group, KMUTT
Division of Materials Technology, School of Energy, Environment and Materials, King Mongkut’s University of Technology (KMUTT), Thonburi, Thailand
PCT-4 Conference, Bangkok (March 20th, 2014)
Assoc. Prof. Dr. Jatuphorn Wootthikanokkhan
Introduction to polymers for energy related applications
Polymers for DMFC fuel cells Sulfonated PVOH Sulfonated PEEK Sulfonated PS
Polymers for solar cells Composite gel electrolyte Donor-acceptor copolymers Fullerene functionalized polymers
Future work
Talk Outline
2
3
1. Developments of polymers for energy related applications ∗ Solar cell components ∗ Low temperature fuel cells
2. Developments of polymers for environment
∗ Biodegradable polymers ∗ Development of new polymers from non-food biomass derived chemicals
3. Work closely with industries
Scope of R&D work at PENTEC
4
Polymer electrolytes and membranes for dye sensitized solar cell, fuel cells and batteries
Semiconducting polymers for polymer solar cells and electrochromic glass
Polymer sealants, films, and binders for solar cells, chromic glass
Types of polymeric materials being developed for uses in energy related applications
Introduction to polymers for energy related applications
Glass
ITO
Donor / Acceptor
Al
Light
PEDOT:PSS
Dye sensitized solar cell
Polymer solar cell
Direct Methanol Fuel cells
Inorganic solar cells (Si)
Introduction to polymers for energy related applications
Examples of polymers used in various alternative energy devices
5
6
Introduction to polymers for energy related applications
Polymers for DMFC fuel cells Sulfonated PVOH Sulfonated PEEK Sulfonated PS
Polymers for solar cells Composite gel electrolyte Donor-acceptor copolymers Fullerene functionalized polymers
Future work
Talk Outline
Type Electrolyte Operating temp.
(°C)
Alkaline Potassium hydroxide and/or anion exchange polymeric membrane
50-90
Proton exchange membrane (PEM)
Polymeric materials 50-125
Direct methanol Polymeric materials 50-120
Phosphoric acid Phosphoric acid 190-210
Molten carbonate Lithium/potassium carbonate mixture
630-650
Solid oxide Stabilized zirconia 900-1000
Polymers for DMFC fuel cells
Types of fuel cell
7
DMFCs have higher energy density (than PEMFC) but exhibit shortcomings such as (a) slower oxidation kinetics than PEFC below 100 °C and
(b) significant permeation of the fuel from the anode to the cathode resulting in a drop in efficiency of fuel utilization upto 50%
(Solid State Ionics 125 (1999), pp. 431–437)
Polymers for DMFC fuel cells
How does the DMFC work?
8
Vehicular mechanism Grottuss mechanism Surface mechanism
In case of the Grottuss mechanism, protons do not move freely in water, but form complexes with water molecules through hydrogen bonds, which allow protons to hop through water very efficiently. , (just as sandbags hop from person to person)
Proton conductive Resistance to methanol Hydrophilic
Thermal stability above 100 °C Resistance to chemicals Good mechanical properties Good process-ability e.g., by solvent
casting Inexpensive (compared with Nafion® ,
1200 U$/m2)
Polymers for DMFC fuel cells Proton conducting
mechanisms
General requirements of DMFC membrane
9
1. Sulfonated PVA-clay nanocomposites
2. Sulfonated PEEK / PVDF blends
3. Sulfonated PS / PVDF blends with compatibilizer
Development of proton exchanges membranes for DMFC fuel cells
Polymers for DMFC fuel cells
Case studies
10
Methanol permeability of PVA is relatively low as compared to that of Nafion
Proton conductivity of the PVA can be induced by carrying out a sulfonation, using various agents
Conductivity of the sulfonated polymer was obtained at the expense of its flexibility
Polymers for DMFC fuel cells
1. Sulfonated PVA-clay nanocomposites
Sulfonated PVA-casted films
Sulfonation of PVA
11
P. Duangkaew, J. Wootthikanokkhan, Journal of Applied Polymer Science, Vol. 109, 452–458 (2008)
Polymers for DMFC fuel cells
1. Sulfonated PVA-clay nanocomposites
CloisiteNa (2 % w/w) Cloisite30B (2 % w/w)
TEM images Structure-property relationships
12
13
C
O
O O
n
C
O
O O
nSO3H
H2SO4
Sulfonated PEEK
PEEK
Sulfonation of PEEK
PEEK is a high performance semi-crystalline thermoplastic.
The sulfonation of PEEK in concentrated sulfuric acid is the only known method
J. Wootthikanokkhan and N. Seeponkai, Journal of Applied Polymer Science, Vol. 102, 5941–5947 (2006)
Polymers for DMFC fuel cells
2. Sulfonated PEEK / PVDF blends
Membranes Proton Conductivity (S/cm)
Methanol Permeability (cm2/sec)
PVDF n/a No methanol crossover
sPEEK/PVDF (10/90) n/a No methanol crossover
sPEEK/PVDF (30/70) n/a No methanol crossover
sPEEK/PVDF (50/50) 7.18 × 10-3 No methanol crossover
sPEEK/PVDF (70/30) 9.10 × 10-3 5.34 × 10-9
sPEEK/PVDF (90/10) 8.99 × 10-3 5.66 × 10-9
sPEEK 10.34 × 10-3 2.35 × 10-7
Nafion 115 10.50 × 10-3 3.39 × 10-7
J. Wootthikanokkhan and N. Seeponkai, Journal of Applied Polymer Science, Vol. 102, 5941–5947 (2006)
Polymers for DMFC fuel cells
2. Sulfonated PEEK / PVDF blends
14
SC=S CH2 CH
CH2 CH
CH2 C
CH3
CH2 CH
N(C2H5)2
+
Pr opagation
(C=O)OCH3
SC=S
N(C2H5)2
SC=S
N(C2H5)2
CH2
CH2 C
CH3
(C=O)OCH3
CH2 C
CH3
(C=O)OCH3
PS-b-PMMA
CH2
CH2 C
CH3
CH2 CH
C
O
OCH3
(1) (2)
PS-b-PMMA were synthesized for uses as a compatibilizer for sPS/PVDF blend membranes
Polymers for DMFC fuel cells
3. Sulfonated PS / PVDF blends Synthesis of PS-b-PMMA Sulfonation of PS
The reaction system is homogeneous
sPS/PVDF is an incompatible blend
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Without block copolymer With block copolymer
SEM micrographs
AFM micrographs
J. Wootthikanokkhan, P. Piboonsatsanasakul, S. Thanawan, Journal of Applied Polymer Science, 107 issue 2 (2008)1325-1336.
Polymers for DMFC fuel cells
3. Sulfonated PS / PVDF blends Morphology of sulfonated PS/PVDF blend membranes
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Introduction to polymers for energy related applications
Polymers for DMFC fuel cells Sulfonated PVOH Sulfonated PEEK Sulfonated PS
Polymers for solar cells Composite gel electrolyte Donor-acceptor copolymers Fullerene functionalized polymers
Future work
Talk Outline
17
Polymer for solar cells
Classifications of solar cells
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Solar cells
Technologies based on Si wafer
Thin film technologies
New emerging technologies
Monocrystaline
Polycrystaline
Amorphous Si
Compound semiconductor CIGS
Quantum dot
Dye sensitized solar cells
Hybrid (inorganic-organic)materials solar cells
Organic PV
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Polymer for solar cells
http://en.wikipedia.org/wiki/File:PVeff(rev110408U).jpg
Research Challenges
To improve power conversion efficiency;
* Reduction of photon loss * Reduction of exciton loss
* Reduction of carrier loss
* Minimize fullerene aggregation Research problems
Efficiency enhancement
Cost reduction
Stability
To improve stability and durability of the cells;
* Use inorganic or hybrid materials
* Encapsulate with polymer film
Polymer solar cells
To reduce cost;
* Alternative photoactive materials are needed to be developed
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OMe
O
S
C6H13
n
O
On
MEH-PPV
Fullerene [C60]
PCBM
Polymer solar cells
Photo-active materials Hetero-junction
P3HT
Electron donors Electron acceptors
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Donor/Acceptor BHJ materials Efficiency (%) References
PTh/C60 0.09 [Fan et al., 2006]
P3HT/PCBM 4.6 [Gadisa et al., 2009]
P3PT/PCBM 4.3 [Gadisa et al., 2009]
P3BT/PCBM 3.2 [Gadisa et al., 2009]
P3HT/PCBM 2.0 [Sivula, 2006]
P3HT/PDI (perylene diimide) 0.3 [Rajaram, 2009]
P3HT/PCBM 0.45 [Vanlaeke, 2006]
P3HT/PCBM (after anealing) 2.7 [Vanlaeke, 2006]
N/A 10* Y.W.Su, Materials Today 2012, * Mitsubishi Chemicals
Polymer solar cells
Varieties of efficiency values
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Absorption of photon by organic semi-conductor produce excited electron-hole pairs (Exciton)
Binding energy between electron-hole of organic material is relatively high (typically 1.0 eV) as compared to that of inorganic material (0.1 eV)
Diffusion length of photo-excited electron-hole pair (exciton) is relatively short (5-10 nm) as compared to the distance between electrode (film thickness)
The electron-hole pairs tend to recombined before traveling into the electrode.
This means that only small amount of the excitons are capable of spitting into free electron and hole
Polymer solar cells Exciton loss
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Durability and lifetime of the DSSC cells, mainly due to liquid electrolyte leakage, have yet to be further improved
(Chung et al., Nature, 2012)
Corrosion of metal electrode due to the use of iodine redox couple
(Chen et al., 2010; Wang et al., 2011)
Challenges for the development of DSSC
Dye sensitized solar cells
Some strategies for improving durability of DSSC
Using a nonvolatile ionic liquid (such as immidazolium salts)
Applying one dimensional nanostructure of TiO2 (nanotubes, nanofibers) to overcome the “pore filling problem”
Using inorganic-organic hybrid (perovski compound and polymer) as light absorber and hole transporter
(Gratzel et al., Materials Today, 2013 and Heo et al., Nature Photonics, 2013)
Developing solid based electrolytes
Encapsulate the cell 24
Electrolytes Properties
Mechanical Thermal stability
Electro-chemical stability
Conductivity (S/cm)
Organic Liquid Low Low Moderate High (1×10-3 - 1×10-2 )
Room temp. ionic liquid Low High Low to
Moderate
Moderate to High
Solid polymer electrolyte High High High Very low (1×10-4 - 1×10-9)
Gel polymer electrolyte Moderate Moderate Moderate Moderate
Reproduced from Jung et al., Bull. Korean Chem Soc, 2009
Future trends : Development of nanocomposite gel polymer electrolyte
Polymer for solar cells Comparison of properties of various electrolytes
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1. Preparation of composite gel polymer electrolyte based on La2O3 filled P(VDF-HFP) nanofibers
2. Synthesis of P3HT-b-PSFu and photovoltaic performance of P3HT/PCBM containing the copolymers
3. Synthesis of fullerene functionalized polymers for uses as an electron acceptor in BHJ solar cells Fullerene grafted PS Fullerene grafted DHPVC
Development of polymer for solar cells
Polymers for solar cells
Case studies
26
12 wt% 14 wt%
16 wt% 18 wt%
Porosity and electrolyte uptake of the nanofibers are greater than those of a solution casted P(VDF-HFP) film
Averaged diameter of electrospun P(VDF-HFP) nanofibers increased with polymer concentration
1. Preparation of Composite Gel Polymer Electrolyte based on La2O3 filled P(VDF-HFP) Nanofibers
Polymers for solar cells
Morphology and properties of electrospun PVDF-HFP nanofiber
0100200300400500600700
0 20 40 60 80Ele
ctro
lyte
upt
ake
(%)
Wetting time (min)
E-10 kV
E-12 kV
E-14 kV
E-16 kV
casting
0
20
40
60
80
100
E-10 kV E-12 kV E-14 kV E-16 kV casting
Poro
sity
(%)
SEM image of a casted film
27
1. Preparation of Composite Gel Polymer Electrolyte based on La2O3 filled P(VDF-HFP) Nanofibers
Polymers for solar cells
Sample Electrolyte
uptake (%)
Relative
absorption ratio
∆HM
(J/g)
Ion conductivity
(S/cm) Casted P(VDF-HFP) film 102.89 0.84 62.29 6.04 x 10-4
Electrospun P(VDF-HFP)
(10 kV) 562.24 0.69 48.81 1.02x 10-3
Electrospun P(VDF-HFP)
(12 kV) 607.95 0.76 45.94 1.11 x 10-3
Electrospun P(VDF-HFP)
(14 kV) 572.59 0.83 52.68 1.22 x 10-3
Electrospun P(VDF-HFP)
(16 kV) 620.78 0.82 51.03 1.12 x 10-3
Electrospun PVDF-HFP nanofibers
28
1. Preparation of Composite Gel Polymer Electrolyte based on La2O3 filled P(VDF-HFP) Nanofibers
Polymers for solar cells
Electrospun P(VDF-HFP)-La2O3 composite nanofibers
SEM image (SE) EDX dot map
0.00.10.20.30.40.50.60.7
0 2 4 6 8 10 Ave
rage
fibe
r di
amet
er (𝜇m
)
La2O3 content (%) 29
Sample ∆HM
(J/g)
Ion conductivity
(S/cm)
P(VDF-HFP) 52.68 1.22x 10-3
P(VDF-HFP) + 2%La2O3 44.29 1.20x 10-3
P(VDF-HFP) + 4%La2O3 44.02 1.32x 10-3
P(VDF-HFP) + 6%La2O3 45.97 1.12x 10-3
P(VDF-HFP) + 8%La2O3 43.05 1.30x 10-3
P(VDF-HFP) + 10%La2O3 43.74 1.43x 10-3
N.Rattanathamwat, J. Wootthikanokkhan, N. Nimitsiriwat, C. Achayanont, U. Asawapirom, and A. Keawprajak , International Journal of Polymeric Materials, 63(2014)448-455
Polymers for solar cells 2. Synthesis of P3HT-b-PSFu and photovoltaic performance of P3HT/PCBM containing the copolymers
Polymers solar cells
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P3HT/PCBM
S
Hex
OCH3
O
n x y
P3HT-b-PSFu
OMe
o
PCBM
S n
P3HT
P3HT P3HT-b-PSFu
PCBM
3.1 eV
5.1 eV
4.2 eV
6.0 eV
3.3 eV
4.8 eV
4.3 eV
4.7 eV
e-
e- e-
h+ h+
h+
Al
ITO
AFM micrographs (topographic image) of P3HT/PCBM containing different type
of donor-acceptor block copolymers
Energy levels of P3HT, PCBM and P3HT-b-PSFu
Polymers for solar cells 2. Synthesis of P3HT-b-PSFu and photovoltaic performance of P3HT/PCBM containing the copolymers
Polymers solar cells
N.Rattanathamwat, J. Wootthikanokkhan, N. Nimitsiriwat, C. Achayanont, U. Asawapirom, and A. Keawprajak , International Journal of Polymeric Materials, 63(2014)448-455 31
CH2 CH CH2 CH S C
S
N
C2H5
C2H5
CH2Cl
CHH2C CH
CH2Cl
H2C
S C
S
N
C2H5
C2H5
C
S
N
C2H5
C2H5
TD
CH2 CH CH2 CH S C
S
N
C2H5
C2H5
H2C
fullerene
x y
++
UV 4 h.Styrene
x y
PSFu
ATRA80 C, 3 h.
Chloromethyl styrene
PS-PCMS
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0 10 20 30 40 50 60 70 80 90 100Acceptor material content (pph)
Eff
icie
ncy*
10-2
(%
)
C60
PSFu 3
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0 20 40 60 80 100
Acceptor material content (pph)
Effic
iency
*10-2
(%)
PSFu 3 C60
rd-P3HT
rr-P3HT
Polymers solar cells
3.1 Synthesis of fullerene grafted polystyrene [PSFu]
Effects of acceptor type and content on PCE
32
THF/toluene mixture, which is a good co-solvent for rd-P3HT, also favors the solubility of PSFu
Dichlorobenzene which is a good solvent of rr-P3HT also promotes a better solubility and prolongs some aggregation of the C60
Polymers solar cells
3.1 Synthesis of fullerene grafted polystyrene [PSFu]
Optical micrographs of various P3HT/acceptor blend films
20 pph C60 60 pph C60
20 pph PSFu 60 pph PSFu (a) (b) (c)
(d) (e) (f)
20 µm
rd-P3HT rr-P3HT
33
2 different techniques can be used;
1. Atom transfer radical addition
2. AIBN based fullerenation
Polymers solar cells
Preparation of fullerene grafted PVC and fulllerene grafted DHPVC
34
3.2 Fullerene functionalized dehydrochlorinated PVC
35
Polymers solar cells
3.2 Fullerene functionalized dehydrochlorinated PVC
-10
-5
0
5
10
15
20
25
30
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
J (m
A/cm
2)
Voltage (V)
PCBM (Left) 1sttest
DHN05 90-10(Left) 2nd test
DHN05 95-5(Left) 1st test
PVCN5 90-10(Left) 2nd test
PVCN5 95-05(Left) 2nd test
Acceptor materials *
Power Conversion Efficiency (%)
PCBM 0.51
Fullerene (C60) 0.16
C60-g-DHPVC 0.01
PCBM /C60-g-DHPVC (95/5) 0.26
PCBM /C60-g- DHPVC (90/10) 0.48
PCBM /C60 –g- DHPVC (80/20) 0.71
PCBM /C60 –g- DHPVC (70/30) 1.34
PCBM /C60 –g- DHPVC (60/40) 0.66
PCBM /C60 –g- DHPVC (50/50) 0.70
Table II Power conversion efficiency of bulk heterojunction polymer solar cells containing different types of electron acceptor phase * P3HT/acceptor = 100/60 % w/w
Introduction to polymers for energy related applications
Polymers for DMFC fuel cells Sulfonated PVOH Sulfonated PEEK Sulfonated PS
Polymers for solar cells Composite gel electrolyte Donor-acceptor copolymers Fullerene functionalized polymers
Future work
Talk Outline
36
Types of energy devices
Research problems/ Challenges
Materials to be developed
Polymer solar cell (PSC)
Alternative photoactive materials (electron acceptors) for BHJ
Electrospun nanofibers based on C60-g-DHPVC/PCBM
Fullerene grafted graphene
Dye sensitized solar cell (DSSC)
Avoiding corrosion Iodine free electrolytes
(Flexible) PSC & DSSC Durability enhancement New encapsulants and sealing films
Future work
Examples of our future work
37
Fundamental knowledge in polymer science can contribute
significantly to the progress and developments of energy
technology.
There are plenty of research problems and opportunities to
continue working on. These include the developments of new
materials (organic, inorganic and hybrid) for enhancing efficiency
and durability of the energy cells.
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Concluding Remarks
∗ The Nanotechnology Center (NANOTEC), Ministry of Science and Technology, Thailand, through its program of Center of Excellence Network.
∗ Thailand Research Fund (TRF) and the Commission on Higher Education, the Ministry of Education for providing research grant. (Grant code: RMU 5180049)
∗ Dr. Chanchana Thanachayanont (MTEC)
∗ Dr. Udom Assawapirom (Nanotec)
∗ Mr. Anusit Keawprajak (Nanotec)
∗ Dr. Sombat Thanawan (Mahidol University)
∗ Ms. Narumon Seeponkai (Ph.D student)
∗ Ms. Noparat Keaitsirisart. (M.Eng. Student)
Acknowledgements
39
Thank You for Your Attention Questions & comments are welcome
iThedooktm Photographer: http://ithedook.multiply.com
Progress in the Development of Polymeric Materials for Alternative Energy Devices at PENTEC research group, KMUTT