from nanomolecular junction to nano-structured ... nsf...from nanomolecular junction to...
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From Nanomolecular Junction to Nano-structured Semiconducting Polymer Organic Solar CellsPolymer Organic Solar Cells
Luping YuDepartment of Chemistry The University of Chicago
NSF Nanoscale Science and Engineering Grantees Conference12/07/2010
Semiconductor p-n junction
Sequential assembling of new diode molecule and related STM topography
S S
Me Me
SMe3SiN
S
N
S
Me Me
S CNS S S S
NaOCH3, THFGold film
dodecanethiolate SAM
S S
Me Me
SMe3SiN
S
N
S
Me Me
S Au film
on Au (111)mica
(Bu)4NFGold Nanoparticle solution.
S S
Me Me
SN
S
N
S
Me Me
SAu Au film
Control Electron Transport Through Sequential Assembly of Diode Molecules
0.0
0.2
0.4
A) b
0.0
0.2
0.4
A) b
S S SS S
i
S
iS
S
S
N
S
S N
S
S
S
S
NS
SN
S
S S SS S
i
S
i
-0 8
-0.6
-0.4
-0.2
Cur
rent
(n 5 pA 10 pA 25 pA 50 pA 75 pA 100 pA150 pA-0 8
-0.6
-0.4
-0.2
Cur
rent
(n 5 pA 10 pA 25 pA 50 pA 75 pA 100 pA150 pA
STS measurement setup for the assembly of diode molecules-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-1.0
-0.8C
VBias (V)
150 pA 200 pA
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-1.0
-0.8C
VBias (V)
150 pA 200 pA
0 2
0.3
0.4
0.5
-0.1
0.0
0.1
0.2
A)
0.6
0.8 50 pA 100 pA 200 pA 300 pA 400 pA500 pA
(nA
)
0.6
0.8 50 pA 100 pA 200 pA 300 pA 400 pA500 pA
(nA
)-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-0.1
0.0
0.1
0.2
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-0.5
-0.4
-0.3
-0.2
Cur
rent
(nA
0.0
0.2
0.4 500 pA 600 pA 700 pA 800 pA
Cur
rent
0.0
0.2
0.4 500 pA 600 pA 700 pA 800 pA
Cur
rent
V
Bias(V)V
Bias(V)
Opposite rectification direction was obtained when the orientation of diode molecule changed
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-0.2
VBias (V)
a-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
-0.2
VBias (V)
a
Studies of Infrared Spectroscopy
vibr
atio
nN N
NC0.02 Si-C
H3
defo
rmat
ion
N NS S
SiMe3
Na+EtO-AuC-H
sym
.
N
N
N
NS S
SiMe3
x 100
x 100
x 100
N NS S H
F-
800 1000 1200 1400 1600 1800
Wavenumber (cm-1)
N N
Ch t i ti f th A bl STM i
bb
Characterization of the Assembly: STM microscopy
a ba b c
10 nm 50 nm 10 nm10 nm 50 nm 10 nm 10 nm
C t t t STM t h f ( ) d d thi l/1 SAMConstant-current STM topography of (a) dodecanethiol/1 SAM on Au(111) after attachment of Au NP to the top termini of 1. Inset: High-resolution image of the DDT SAM. (b). Image of a single
AuNP (c) molecule with (yellow circle) and without (green circle)AuNP. (c) molecule with (yellow circle) and without (green circle) AuNP STM imaging conditions: VBias=+1.0 V, It=1 pA
Effect of Protonation
SN N
N N
S
N N
N N
S
H+
H
S S S S SSSSS S S S S SSSSS
+H+
-H+
0.10 100 Before protonation
S S S S S S SSSSS
-0.2
-0.1
0.0
nt (n
A)
+H+0.050
0.075
0.100 p After deprotonation
nt (n
A)
-0 6
-0.5
-0.4
-0.3
Cur
ren
H+
-0.025
0.000
0.025
Cur
re
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5-0.6
VBias (V)-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
VBias (V)
Photovoltaic Effect of Monolayer of Molecular Diode Array Solar Cell
Diode array assembly
S
Au transferred by Stamp
NNArea: 50 x 50 m2
at 95 kN N
S S S S SSSSS
Au substrate
Molecular Wire Array
S
Molecular Wire Array
S
S
S
S S S SSSSS S
Solar Energy
Illustration by Peter Schrankhttp://www.economist.com/displayStory.cfm?story_id=14082027
http://www.rise.org.au/info/Applic/Solarpump/index.html
Organic and Organic/Inorganic Hybrid PVExciton ExcitonExciton
Light
ExcitonExciton Dissociation
Charge Transport
Hopping
+_
• Low cost, easy processing, and flexibility.
D A D+ A-
• Factors to be considered;
I. Efficient light absorption in whole solar spectrum-Low band gap.II Efficient exciton dissociation Proper driving force for the chargeII. Efficient exciton dissociation-Proper driving force for the charge
separation; energy level match between donor and acceptor.III. Effective charge transport-Balanced carriers’ mobility and
effective overlap.IV. Maximized Voc-HOMO of donor and LUMO of acceptor.
10
A ti l f i l llActive layers of organic solar cells.
Donor-acceptor Bulk heterojuction Idealized solar cellDonor acceptordouble layers1986, Tang.
Bulk heterojuctione.g. P3HT/PCBM
Idealized solar cellactive layerself-assembly
Novel Semiconducting Polymers Exhibiting High Solar Conversion Efficiency
S
COOC12H25
S
S
OC8H17
Sn SnPd(0)(PPh3)4
DMF/Toluene 110 oCn + n
S BrBrS
OC8H17
DMF/Toluene, 110 C
1.6
PTB1 l ti
120 b
0.8
1.2
PTB1 solution PTB1 film PTB1-PCBM blend film
zed
ABS 80
120 b
PTB1 film PTB1/PC61BM film
ount
s (a
.u.)
0.6
0.8
1.0
P3HT Film P3HT Solution
ized
AB
S300 400 500 600 700 800
0.0
0.4
Nor
mal
i
700 800 900 1000
0
40
Pho
ton
co
400 600 8000.0
0.2
0.4
Nor
mal
W l th ( )
12
300 400 500 600 700 800
Wavelength (nm)
700 800 900 1000
Wavelength (nm)Wavelength (nm)
Solar Cell composition, Structure and Their Performances
O
O
S
OC8H17
S
Al
S
OC8H17S
C12H25OOC
n
Ch t i ti
PTB1 PC61BM
Characteristics
Jsc = 12.5 mA/cm2, Voc = 0.57 V FF = 0.55 PCE = 4.8 % PCE 4.8 %
13
Solar Cell Performances with Different AcceptorsOC8H17
CaS
S
OC8H17
S
S
n
C12H25OOC
PTB1
PCE = 5.6%
14
Explanation for the good properties of PTB11.6
PTB1 solution
0.8
1.2
PTB1 solution PTB1 film PTB1-PCBM blend film
orm
aliz
ed A
BSReasons:1. Close to optimal band-gap at 1.6 eV.
300 400 500 600 700 8000.0
0.4
No
Wavelength (nm)
1 0
0.4
0.6
0.8
1.0
P3HT Film P3HT Solution
mal
ized
AB
S2. Planarity and rigidity of polymer chain-UV/vis spectra did not change much.
400 600 8000.0
0.2Nor
m
Wavelength (nm) 3. Balanced mobility 4.5×10-4 cm2/v.s
1.0
1.5
2.0
5 (A0.
5 /cm
)
l=65 nm l=100 nm
3 y 4 5 /vs P3HT 2.7×10-4 cm2/v.s. as indicated by the high fill factors.
0 1 2 3 40.0
0.5
J0.5
Vap-Vbi-Vr (V)
4. Preferred interpenetrating network
TEM image of PTB1/PCBMAFM i f PTB1/PCBM TEM image of PTB1/PCBMAFM image of PTB1/PCBM
16
5. Favored Charge separation Dynamics-TA spectra of PTB11. the visible 2. NIR region after 600 nm
4
-2
0
2
PTB1a
3 0
3.5
4.0
4.5
PTB1b
light excitation.
12
-10
-8
-6
-4
0.5 ps 1 ps 10 ps 100 ps
A (O
D)
1 0
1.5
2.0
2.5
3.0
A
(OD
)
500 550 600 650 700 750-16
-14
-12p
500 ps
Wavelength (nm)
900 1000 1100 1200 1300 1400 1500 16000.0
0.5
1.0
Wavelength (nm)1
3 5
PTB1/PCBM
PTB1/PCBM-2
-1
0
1
c2.5
3.0
3.5d
-6
-5
-4
-3
A
(OD
)
1.0
1.5
2.0
A
(OD
)
500 550 600 650 700 750-8
-7
Wavelength (nm)900 1000 1100 1200 1300 1400 1500 1600
0.5
Wavelength (nm)
6. Favored polymer chain packing-X-ray scattering studies
PTB1 film PTB1/PCBM composite a. In-plane linecuts of GISAXS.
PTB1PTB1/PCBM 1:1a
1000
10000 PTB1/PCBM 1:2PTB1/PCBM 2:1
Inte
nsity
1800
0.01 0.110
100
q (A-1)
800
1000
1200
1400
1600
1800
PTB1PTB1/PCBM 1:1PTB1/PCBM 1:2PTB1/PCBM 2:1PTB1/PCBM annealed
nten
sity
b
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00
200
400
600
800In
1q (A-1)(b) Out-of-plane line-cuts of GIWAXS.
7. Favored charge transfer complex dissociation-Magnetic Field Effect on Photocurrent
12ITO/PEDOT/Polymer/Al
2.5P3HT:PCBM=1:0.8 PTB1
ITO/PEDOT/Polymer:PCBM/Ca/Al
g
PTBx
-2-101
P3HT PTB1PTB2M
FP (%
)
1.01.52.0
0 3006009000.00.20.40.60.81.0
-2V0V
MFP
(%)
Magnetic field (mT)
MFP
(%)
PTB1 PTB2
0V
PTBx
(PTB)1 (PTB)3Light excitation
Exciton dissociation
0 300 600 900-4-32 PTB2M
M ti fi ld ( T)0 300 600 900
0.00.5
-2VM
(e- h+)1 (e- h+)3
Exciton dissociation
Meganetic field (mT) Magnetic field (mT)
• Pure PTB1 and PTB2 polymer, the exciton dissociation under photon illumination is ffi i d i h P3HT
( ) (0)(0)
ph ph
ph
I B II
MFP =
more efficient compared with pure P3HT.
• The bonding energy of charge-transfer exciton at the interface of PTB1 (or PTB2) and PCBM is weaker than the bonding energy in P3HT and PCBM system.
• Polymer PTB1 shows less recombination of dissociated electrons and holes compared with polymer PTB2.
ITO/P l PCBM/Al •The permittivity or dielectric constant of
8. Larger dielectric constant-Impedance Studies
150
200 P3HT PTB1PTB2
ITO/Polymer:PCBM/Al
nce
( 2) ( 1) ( 3 )PTB PTB P HT
•The permittivity or dielectric constant of pure PTB2, PTB1, and P3HT have the relationship
50
100
PTB2
apac
itan ( 2) ( 1) ( 3 )r r rPTB PTB P HT
0 20 40 60 80 100 1200
C
Light intensity (mw/cm2)
•The effective permittivity or dielectric constant of the three blend systems also keep the relationshipLight intensity (mw/cm )
( 2 : ) ( 1: ) ( 3 : )eff eff effPTB PCBM PTB PCBM P HT PCBM
p p
• Strong local dielectric interaction lead to more efficient dissociation and less geminate recombination.
New polymers with high solar conversion efficiency
0.8
1.0 PTB1 PTB2 PTB3 PTB4 PTB5A
BS
b
0 2
0.4
0.6 PTB6
Nor
mai
lized
A
400 600 8000.0
0.2N
Wavelength (nm)
4 PTB1 PTB2PTB3cm
2 )Current – voltage characteristics of polymer/PC61BM solar cells
4
m2 )
a PTB3 PTB4PTB5
60b
-8
-4
0 PTB3 PTB4 PTB5 PTB6
t den
sity
(mA
/c
-8
-4
0
dens
ity (m
A/c
m PTB5
20
30
40
50
EQ
E (%
)
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8
-12
Cur
rent
Voltage (V)-0.4 -0.2 0.0 0.2 0.4 0.6 0.8
-12
Cur
rent
d
Voltage (V)400 500 600 700 800
0
10
Wavelength (nm)
Polymers Voc (V) Jsc (mA/cm2) FF (%) PCE (%)PTB1 0 58 12 5 65 4 4 76
Note: a. Devices prepared
g ( )
Table 2. Characteristic Properties of Polymer Solar Cells.
PTB1 0.58 12.5 65.4 4.76PTB2 0.60 12.8 66.3 5.10PTB3 0.74 13.1 56.8 5.53PTB4 0 76 9 20 44 5 3 10
p pfrom mixed solvents dichlorobenzene/diiodooctance (97/3, v/v)PTB4 0.76 9..20 44.5 3.10
PTB5 0.68 10.3 43.1 3.02PTB6 0.62 7.74 47.0 2.26PTB3a 0 72 13 9 58 5 5 85
v/v).
b. Value after spectral correction.
PTB3a 0.72 13.9 58.5 5.85PTB4a 0.74 13.0 61.4 5.90(6.10b)PTB5 a 0.66 10.7 58.0 4.10
(under AM 1.5 condition (100mW/cm2)
TEM images of polymer/PC61BM blend films:
a. PTB1b. PTB2c PTB3c. PTB3d. PTB4e. PTB5f. PTB6prepared from mixedsolvents dichlorobenzene/diiodooctance (97/3 v/v):diiodooctance (97/3, v/v): g. PTB3h. PTB4i. PTB5
CAFM images (right) of polymer/PC61BM blend films
PTB2 PTB6
The white regions in CAFM (low current) correspond to the PCBM-rich areas, consistent with hole current images and topography images.
24
consistent with hole current images and topography images.
PTB4/PC71BM Solar Cells
70
80
PC71BM -4
-2
0
/cm
2 )
40
50
60 PC61BM
E (%
)
-10
-8
-6
4
ensi
ty (m
A/
10
20
30
EQ
E
-16
-14
-12
10
Cur
rent
De
300 400 500 600 700 800 9000
10
Wavelength (nm)
0.0 0.2 0.4 0.6 0.8-16C
VoltageCurrent – voltage plot of PTB4/PC71BM
l llg ( )
solar cells
Voc (V) Jsc (mA/cm2) FF (%) PCE (%)
PTB4/PC61BM 0.74 13.0 61.4 5.9 (6.1a)
a. Value after spectral correction
PTB4/PC71BM 0.70 14.8 64.6 6.7(7.1a)
PTB7/PC71BM Solar CellsORa 70
S
S
OR
S
n
a
50
60
70
S
ORS
ROOC
nF
R = 2-ethylhexyl PTB7 30
40
EQE
0
10
20
0.8
1.0
1.2 PTB7 PTB7/PC71BM
zed
AB
S
300 400 500 600 700 800 9000
Wavelength (nm)400 500 600 700 800
0.0
0.2
0.4
0.6
Nor
mal
iz
Wavelength (nm)
-8
-6
-4
-2
0
(mA
/cm
2 )
Voc(V)
Jsc(mA/cm2)
FF(%)
PCE(%)
Jsc (Cal.)(mA/cm2)
Error (%)
a. DCB 0.74 13.95 60.25 6.22
b DCB+DIO 0 74 14 09 68 85 7 18 13 99 0 74
g ( )
0.0 0.2 0.4 0.6 0.8
-14
-12
-10Jsc
(
Voc (V)
b. DCB+DIO 0.74 14.09 68.85 7.18 13.99 0.74
c. CB 0.76 10.20 50.52 3.92d. CB+DIO 0.74 14.50 68.97 7.40 14.16 2.34
The Best Solar cell Systems:PTB7/PC71BM
-6
-4
-2
0
cm2 )
-14
-12
-10
-8
-6
Jsc
(mA
/c
0.0 0.2 0.4 0.6 0.8Voc (V)
Voc (V) Jsc (mA/cm2) FF (%) PCE (%)
PTB7/PC71BM 0.74 14.0 68.6 7.4
Polymer Solar Cells Efficiency Chart
O
O
n
MDMO-PPV
NS
N
SS
R R
nR = 2-ethylhexyl
S n
PCPDTBT
Effects of fluorination on physical properties.Synthesis of monomers
S
S
OR1
S
S
OR1Br
Br BrS
S
OR1BrBr2
CHCl3
1. BuLi
2. MeOH
1. BuLi
2. PhSO2NF
Synthesis of monomers
OR1 OR1Br OR1
Br
S
OR1FS
OR1F
Br BrS
OR1F
M S S MBr2 1. BuLi
S
OR1F
S
OR1F
Br BrS
OR1F
Me3Sn SnMe3CHCl3 2. SnMe3Cl
Polymerization
S
S
BrBr
S
S
OR1X2
Me3Sn SnMe3
Pd(PPh3)4
DMF/Toluene+
S*
S
S
OR1X2
*n
X1
OR2O OR1
X2
DMF/TolueneS
X1
OR2O
S
OR1X2
PTBF0 : X1 = H, X2 = H, R1 = n-octyl, R2 = 2-ethylhexyl PTBF2 : X1 = H, X2 = F, R1 = 2-ethylhexyl, R2 = 2-ethylhexyl
PTBF1 : X1 = F, X2 = H, R1 = 2-ethylhexyl, R2 = 2-ethylhexyl PTBF3 : X1 = F, X2 = F, R1 = 2-ethylhexyl, R2 = 2-ethylhexyl
1.0
S
PTBF0 PTBF1
Physical Properties of fluorinated polymers
3 5
-3.0
3 59
-3.22 -3.31
3 60
0 4
0.6
0.8
mal
ized
AB
S
PTBF2 PTBF3
-4.5
-4.0
-3.5
eV
-3.59-3.60
400 500 600 700 800
0.2
0.4
Nor
m
-5.5
-5.0
PTBF0 PTBF2 PTBF3PTBF
-5.15-4.94
-5.41 -5.48
Wavelength (nm)
Table 2. Molecular weights and absorption properties of the polymers
1
Polymer Mw
(Kg/mol)
PDI max (nm) onset (nm) Egopt (ev)
p ope es o e po y e s
(Kg/mol)
PTBF0 23.2 1.38 683, 630 780 1.59
PTBF1 97.5 2.10 671, 628 737 1.68
PTBF2 26.7 2.38 670, 611 709 1.75
PTBF3 78.4 2.61 670, 613 717 1.73
Calculated values of dihedral angles and energy levels of polymers at the B3LYP/6-31G* level of theory
Polymer Dihedral angle
(degree)
LUMO (eV) HOMO (eV) Eg (eV)
PTBF0 163 3 2 67 4 88 2 21PTBF0 163.3 -2.67 -4.88 2.21
PTBF1 161.0 -2.73 -4.99 2.26
PTBF2 179.5 -2.79 -4.89 2.10
PTBF3 179.8 -2.87 -4.98 2.11
1500
2000 PTBF0 PTBF1 PTBF2 polymer d1 (Å) d2 (Å)
The d-spacing values of the polymers.X-ray diffraction
500
1000
Cou
nts PTBF3
p y ( ) ( )
PTBF0 3.8 31
PTBF1 4.0 28
10 20 30 40 50
0
2 Theta (degree)
PTBF2
PTBF3
4.0
4 0
29
28
Pol merPolymer/PC71BM
Sol entJsc
Voc (V) FF PCE(%)
Solar cell characteristics and TEM images of composites
Polymer(w/w ratio)
Solvent(mA/cm2)
Voc (V) FF PCE(%)
PTBF0 1:1 DCB 14.1 0.58 62.4 5.1
PTBF1 1:1.5 DCB 14.0 0.74 60.3 6.2
PTBF1 1:1.5 DCB/DIO 14.1 0.74 68.9 7.2
PTBF2 1:1.5 DCB 11.0 0.68 43.4 3.2
PTBF2 1:1.5 DCB/DIO 11.1 0.68 42.2 3.2
PTBF3 1:1.5 DCB 9.1 0.75 39.4 2.7
PTBF3 1:1 5 DCB/DIO 8 8 0 68 39 0 2 3PTBF3 1:1.5 DCB/DIO 8.8 0.68 39.0 2.3
-4
-2
0
/cm
2 )
PTBF0 PTBF1 PTBF2
ab
12
-10
-8
-6
Cur
rent
(mA
/
PTBF3b
-0.2 0.0 0.2 0.4 0.6 0.8
-14
-12C
Voltage (V) PTBF0 (a), PTBF1 (b), PTBF2 (c), PTBF3 (d). Scale bar = 200μm.
c d
T=0 T=10 sec T=20 sec
FT-IR of PTBF3 film on KBr as a function of time of irradiation.
Absorption spectra of PTBF3 film recorded as a function of irradiation time under air.
0.3
0.4
ion
T=30 sec T=40 sec T=50 sec T=60 sec T=70 sec T=80 sec T=95 secT=110 sec
44
48
ance
T= 0 T= 30 min T=1 hr 30 min T=4 hr T=7 hr
0.1
0.2
Abs
orpt
T 110 sec T=130 sec T=150 sec T=180 sec T=220 sec T=8 min T=14 min T=1 hrT=2hr 15min
40
Tran
smitt
a
400 500 600 700 8000.0
Wavelength (nm)
T=2hr 15min T=3hr 30min T=20 hr
1800 1500 1200 900 60036
Wave numbers (cm-1)Decrease in the optical density (max) of
80
100
44
48
ance
T= 0
polymer films.
20
40
60
OD
(%)
PTBF0 PTBF1
36
40
Tran
smitt
a T 0 T= 30 min T=1 hr 30 min T=4 hr T=7 hr
0 30 60 90 120 150 1800
20
Time (Sec)
PTBF2 PTBF3 3900 3600 3300 3000 2700 2400 2100
Wave numbers (cm-1)
Negative charges on the atom position A and B
Optical density (%) of PTBF3 (a) and PTBF1 (b) absorption spectra in three diff t t f ti f l d
Position PTBF0 PTBF1 PTBF2 PTBF3
90
100 TolueneToluene with DABCO
different systems as a function of elapsed photolysis time.
aA ( ) -0.209 -0.214 -0.217 -0.221
B ( ) -0.239 -0.234 -0.250 -0.24960
70
80
90
D (%
)
Toluene with DABCO Toluene-d8
OCH3X20 2 4 6 8 10 12
30
40
50OD
S
SX1
*
H3CO
S
S
OCH3
2
X2
*3
0 2 4 6 8 10 12Time (sec)
90
100 Toluene Toluene with DABCO Toluene-d8
b-4.0
-3.5
-3.0
V
-3.59
-3.22 -3.31
-3.60
O3CO
PTBF0 : X1 = H, X2 = H
PTBF1 : X1 = F, X2 = H
PTBF2 : X = H X = F60
70
80
OD
(%)
-5 5
-5.0
-4.5
eV
-5.15-4.94
PTBF2 : X1 = H, X2 = F
PTBF3 : X1 = F, X2 = F
0 20 40 60 80 100 120 140 160
40
50
Time (min)
-5.5
PTBF0 PTBF2PTBF3PTBF1
-5.41 -5.48
Theoretical Maximum Efficiency Based on Energetics
Eox/onset (V) HOMO (eV)a onset (nm) max (nm)b Band gap (eV)c
0.63 -5.34 735,834 <1.,4 eV
0.5
0.6
0.7
0.2
0.3
0.4
abs
(a.u
.)
400 500 600 700 800
0.1
Wave length (nm)
Power conversion efficiency AM 1.5 (%)S
OO PCBM
Dennler et. al. Adv. Mater. 2009, 21, 1–16
S
S*S *
F F0.78 -1.81 0.61 42.86
Voc Jsc PCE max FF
Summary1. Donor-acceptor diblock co-oligomers exhibit rectification effect.
2. Faster rate in charge separation than in charge recombination was observed. However, to achieve high the photovoltaic effect, more structural designs and extensive synthesis of new materials are needed.
3. Low bandgap polymers are needed to efficiently harvest solar energy. A3. Low bandgap polymers are needed to efficiently harvest solar energy. A judicial selection in bandgap is needed to achieve maximized solar conversion. An optimized band-gap exists as shown by the copolymer system.
4 Hi h l l i ht t b t hi hi h l i4. High molecular weight seems to be necessary to achieve high solar conversion efficiency.
5. Overall, physical properties in a new polymer must be synergistically balanced and , p y p p p y y g yoptimized in order to achieve high efficiency.
6. Photochemical stabilities of the polymeric materials are major concerns that need to accumulate datathat need to accumulate data.
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Acknowledgements:
Yongye Liang Dr. Danqing FengHae Jun Son Dr. Xianshang XiaoT X D F H
Molecular Electronics
Man-Kit NgTao Xu Dr. Feng HeBrigett Carsten Dr. Jiangbin XiaZhou Wang Dr. Wei WangClaire Ray Dr. Autrean GasinierJ B bitt D J B ll k
Hengbin Wang
Jiang Ping
Gustove MoralesJoe Babitto Dr. Joe Bullock
Professor Lin Chen (ANL/NW)Dr. Jianchang Guo (ANL/UC)D J di S k
Gustove Morales
Shengwen Yuan
Yungu LeeDr. Jodi Szarko
Dr. Gang Li (Solarmer)D Y W (S l )
Dr. Hau Wang (Argonn)Dr. P. Thiyagarajan, Dr. K. C. Littrell
Dr. Yue Wu (Solarmer)
NSF, DOE, AFOSR, UC-NSF-MRSECSolarmer Energy Inc., Intel
Dr. V. S. UrbanDr. Binhua Lin
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