-
NREL/PR-2A0-44449NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC
Venue:Plastic ElectronicsBerlin, Germany
Presenter:Garry Rumbles
Date:29th October, 2008
The importance of basic science in addressing the challenges of organic photovoltaics
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Outline:
• The Energy issue
• Photovoltaics
• Why organics?
• Technologies
• Basic issues
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Energy Usage
3
National Renewable Energy Laboratory Innovation for Our Energy Future
Energy Usage
3
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Renewables
4
Theoretical Practical Comments
Wind
Geothermal
Hydro
Biomass
Solar
50 TW 2 TWOffshore and Demographics
1.3 GWNeeds drilling breakthrough
4.6 TW 1 TW 0.3 TW currently
20 TW 6 TW31% of land, 0.3% efficient, Water
1.2 x 105 TW 600 TW Photosynthesis = 90 TW
National Renewable Energy Laboratory Innovation for Our Energy Future
Renewables
4
-
0.1
1
10
100
1000
10000
100000
Peak P
ow
er
Capacity
World
Germ
any
USA
National Renewable Energy Laboratory Innovation for Our Energy Future
Installed capacity!
5
http://en.wikipedia.org/wiki/Photovoltaics
GW
p
National Renewable Energy Laboratory Innovation for Our Energy Future
Installed capacity!
5
http://en.wikipedia.org/wiki?Photovoltaics
http://en.wikipedia.org/wiki?Photovoltaicshttp://en.wikipedia.org/wiki?Photovoltaics
-
National Renewable Energy Laboratory Innovation for Our Energy Future
PV Research Cell Efficiencies
6
http://en.wikipedia.org/wiki/Solar_cell
National Renewable Energy Laboratory Innovation for Our Energy Future
PV Research cell efficiencies
6
http://en.wikipedia.org/wiki/Solar_cell
http://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Solar_cell
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Generic bulk heterojunction device
7
Transparent Substrate
Hole-transport
layer
Metal contact
Active Layer
Transparent Substrate
Hole-transport
layer
Metal contact
Active Layer
S
C6H13
n S
C6H13
S
C6H13
P3HTn
O
O
MDMO-PPV
N
SN
SS
n
PCPDTBT
O
O
S
OO
n
SO3- SO3H SO3H SO3H SO3
- SO3H
S
O O
S
OO
S
O O
S
OO
S
O O
n
Ag
Al
Mg:Ag/Ag
LiF/Al
Ca/Al
Ba/Al
Transparent contact
National Renewable Energy Laboratory Innovation for Our Energy Future
Generic bulk heterojunction device
7
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Transparent Substrate
Hole-transport layer
Metal contact
Transparent contact
Active Layer
How it works
*
Fundamental understanding - Is this how it works?
8
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Plextronics - Plexcore® PV NREL-Certified Performance
1.9eV
Jsc
Voc
Pmax
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Size matters
10
National Renewable Energy Laboratory Innovation for Our Energy Future
Size matters
10
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Champion devices (P3HT:PCBM)
11
Now Realistic Plan* How?
Voc
(V)0.62 0.65 1.1 Lower LUMO (and HOMO)
Jsc
(mA/cm2)10 14 25 Shift absorption to red
FF
(%)67 75 80
Improve transparent
electrode
Efficiency
(%)(4.2) 6.8 22 Larger carrier mobilities
National Renewable Energy Laboratory Innovation for Our Energy Future
Champion devices (P3HT:PCBM)
11
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Device development v Fundamental understanding
12
G. Li et al (UCLA) Nat. Mat., 4(11) 864 (2005)
National Renewable Energy Laboratory Innovation for Our Energy Future
Device development v Fundamental understanding
12
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Tandem Organic Solar Cells
13
J-Y Kim et al (UCSB) Science, 317 222 (2007)
‘6.5%’
A. Hadipour et al (NL), AFM, 16(14) 1897 (2006)
National Renewable Energy Laboratory Innovation for Our Energy Future
Tandem Organic Solar Cells
13
-
40
20
0
Cu
rre
nt
De
ns
ity
(m
A/c
m2
)
-1.0 -0.5 0.0 0.5 1.0
Voltage (V)
ITO Reference
! = 3.5%Jsc = 11.09
Voc = 570.6
FF = 55%
60
40
20
0
Cu
rre
nt
De
ns
ity
(m
A/c
m2
)
-1.0 -0.5 0.0 0.5 1.0
Voltage (V)
SWCNT
! = 3.5%J
sc = 10.65
Voc = 571.8FF = 57.6%
-12
-8
-4
0
4
Cu
rre
nt
De
ns
ity
(m
A/c
m2 )
0.60.50.40.30.20.10.0Voltage (V)
SWCNT, No HIL! = 3.29%
JSC = 11.9 mA/cm2
VOC = 545 mV
FF = 50%
National Renewable Energy Laboratory Innovation for Our Energy Future
Doped, single-walled carbon nanotube electrodes
14
50 !/sq electrodeDeposited by ultrasonic spray RMS Roughness ~ 3nm
T. Barnes et al (NREL), Unpublished.National Renewable Energy Laboratory Innovation for Our Energy Future
Doped, single-walled carbon nanotube electrodes
14
van de Lagemaat et al (NREL). APL, 88 233503 (2006)
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Plasmon enhancement effects
15
0.6
0.5
0.4
0.3
0.2
0.1
0.0
IPC
E
800700600500400
Wavelength (nm)
Reference 1 nm Ag 2 nm Ag 3 nm Ag 4 nm Ag
A. Morfa et al, APL, 92 013504 (2008) and APL, 92 243304 (2008)
7
6
5
4
3
Jsc (
mA
/cm
2)
43210
Thickness of Silver Film (nm)
Also on silver nanohole arrays:
Silver nanoparticles on ITO:
Enhancement due to increased light absorption induced by the plasmonic effect on the particles.Almost doubling of current and efficiency
T. Reilly et al. APL 92, 243304 (2008)
National Renewable Energy Laboratory Innovation for Our Energy Future
Plasmon enhancement effects
15
-
National Renewable Energy Laboratory Innovation for Our Energy Future
750
700
650
600
550
Voc (
mV
)
200180160140120100
Annealing Temperature (°C)
50
45
40
35
30
25
Fill F
acto
r (%)
12
10
8
6
4
2
0
Jsc (
mA
/cm
2)
2.0
1.5
1.0
0.5
0.0
! (%
)
16
Airbrushed devices
National Renewable Energy Laboratory Innovation for Our Energy Future
Air-brushed devices
16
Ferguson et al. (NREL) APL, 92 033301 (2008)
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Polymer:PCBM
2.9 eV
4.2 eV
6.0 eV
5.2 eV
P3
F3
P1
F1
CS FreeCS Trapped
BRP1
BRP*
β
α
H. Ohkita et al (Imperial) JACS, 130, 3030 (2008)
BRP = Bound Radical Pair = D+—A- = P+—F-
States v Bands
17
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Competition with carrier collection
18
Polymer:PCBM
2.9 eV
4.2 eV
6.0 eV
5.2 eV
P3
F3
P1
F1
BRP1
BRP*
Separation
Geminate recombination
Re-associating
TRAPS
‘Recombination’?
Collection
National Renewable Energy Laboratory Innovation for Our Energy Future
Competition with carrier collection
18
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Competition with carrier collection
19
Polymer:PCBM
2.9 eV
4.2 eV
6.0 eV
5.2 eV
BRP1
BRP*
Geminate recombination
Re-associating
TRAPS
National Renewable Energy Laboratory Innovation for Our Energy Future
Competition with carrier collection
19
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Transient Microwave Conductivity (TRMC)
20
National Renewable Energy Laboratory Innovation for Our Energy Future
Transient Microwave Conductivity (TRMC)
20
-
National Renewable Energy Laboratory Innovation for Our Energy Future
!Gmax (!Gt=0): Exciton (or BRP) dissociation efficiency
21National Renewable Energy Laboratory Innovation for Our Energy Future
ΔGmax (ΔGt=0): Exciton (or BRP) dissociation efficiency
21
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Free carrier decay ( t = 0 to 200 ns)
22
National Renewable Energy Laboratory Innovation for Our Energy Future
Free carrier decay ( t = 0 to 200 ns)
22
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Trapping, de-trapping and recombination
23
National Renewable Energy Laboratory Innovation for Our Energy Future
Trapping, de-trapping and recombination
23
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Dark carriers, MEG, Schottky devices
25
National Renewable Energy Laboratory Innovation for Our Energy Future
Dark carriers, MEG, Schottky devices
25
J.M. Luther et al (NREL), Nano letters, 8(10) 3488 (2008)
‘2.1%’
AlITO PEDOT
Depletionlayer
Diffusionlayer
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Concluding remarks
26
• The Energy issue
- We need to provide > 15TW• Photovoltaics
- This is a very good, perhaps the only, solution• Why organics?
- Chemistry• Technologies
- Poised and ready• Basic issues
- We need more understanding
-
National Renewable Energy Laboratory Innovation for Our Energy Future
Acknowledgments
• Andrew Ferguson• Matt Reese• Tom Reilly• Anthony Morfa• Matt White• Xerxes Steirer• Alex Nardes• Ben Rupert• Erkan Kose• Will Rance• Smita Dayal• Xin Ai• Jeremy Bergeson
Funding: US DOE, Office of Science, Office of Basic Energy Sciences.
• Nikos Kopidakis• Sean Shaheen• David Ginley• Jao van de Lagemaat• Teresa Barnes• Jeff Blackburn• Rob Tenent• Brian Gregg• Dana Olson• Joe Berry
The importance of basic science inaddressing the challenges of organicphotovoltaicsOutlineEnergy UsageRenewablesInstalled capacity!PV Research cell efficienciesGeneric bulk heterojunction deviceFundamental understanding - Is this how it works?Plextronics - Plexcore® PV NREL-Certified PerformanceSize mattersChampion devices (P3HT:PCBM)Device development vs Fundamental understandingTandem Organic Solar CellsDoped, single-walled carbon nanotube electrodesPlasmon enhancement effectsAir-brushed devicesFStatesv BandsCompetition with carrier collectionTransient Microwave Conductivity (TRMC)ΔGmax (ΔGt=0): Exciton (or BRP) dissociation efficiencyFree carrier decay ( t = 0 to 200 ns)Trapping, de-trapping and recombinationDark carriers, MEG, Schottky devicesConcluding remarksAcknowledgments