organic-inorganic hybrid materials for ir-photodetection ... · 4/20/2010 · * photopatternable...
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7th Korea-US Nano Forum Seoul, April 5-6, 2010
Organic-Inorganic Hybrid Materials for IR-Photodetection and PhotovoltaicsIR-Photodetection and Photovoltaics
20nm
Kwang-Sup LeeD f Ad d M i lDepartment of Advanced Materials,
Hannam University, Daejeon 305-811, Korea
Contents
I d i- Introduction
Quantum Dot based Hybrids- Quantum Dot-based Hybrids * Enhancing the Photocurrent Density* Photopatternable Quantum Dots* Photopatternable Quantum Dots
- Low Bandgap PolymersLow Bandgap Polymers
- C60 Derivatives
- Summary
IR Photodetection
Increase detectivity Increase number of applicationsMedical W hMedical
(Thermal Imaging) WeatherMilitary
Astronomy: Infrared Image of
the Milky Wayy y
Solar Spectrum
(Nanocrystal Quantum Dots)
Pb (Lead)Se (Selenium)Se (Selenium)
PbSe (for IR)CdSe, InP, InP-CdS core-shell
(for visible) Z S CdS (f UV)
• Semiconducting characteristics
• Excellent quantum size effects
ZnSe, CdS (for UV)
• Excellent quantum size effects
• Efficient excitonic generation
• Tunable absorption and emission inTunable absorption and emission in the UV to IR
Tuning of Spectral Response by Choosing Quantum Dots
AbsorptionLuminescence
λ
ZnSe
Broadband Absorber
CdSe, InP
λ
CdSe, InPQuantum Dots
PbSe
λ
CdSe QD20nm
Preparation of PbSe Nanocrystals
Ar
precursors
Thermocouple
organic capping toorganic capping toenable dispersionenable dispersion
Heating mantlemantle
Stir plate reactants + solvent
Semiconductor quantum dotcore-shell/bipods/tripods/ tetrapods
(PbO + Oleic acid in tri n octylamine solvent)+ TOP Se or TBP Se(PbO + Oleic acid in tri-n-octylamine solvent)+ TOP-Se or TBP-Se
Comments: Size and shape control + Surface functionalization of the ti l i t t tparticles are very important steps.
Comparative Environmental Stabilities of IR QDs andIR Organic DyesIR Organic Dyes
Excitation - 720 nmEmission - 830 nm.
Normal laboratory environmental storageenvironmental storage conditions.
Hybrid Materials for IR Photodetection
QD / Pentacene / PVK Polymeric NanocompositePolymeric Nanocomposite
PentacenePentacene
Synthetic Route for Pentacene Precursor
OAli Afzali, et.al, J. Am. Chem. Soc. 2002, 124, 8812.
H3C C N S O+
N-sulfinylacetamidePentacene
O
yPentacene
CH3ReO3 SN
O
CHCl3
Pentacene precursor“Soluble in CHCl3, CH2Cl2
”
Prepared by the Diels-Alder reaction between pentacene & N-sulfinylamide in the presence of a catalytic amount of methyltrioxorhenium,
Device Processing for IR Photodetector
N
O
nSO
Nn
Pentacene precursor PbSe nanoparticle PVK
PVK-Pentacene precursor-PbSe Film Baked in vacuum oven at 240 oC Measured Photoconductivity
Film Composition: PVK 30 wt%, Pentacene precursor 30 wt%, PbSe 40 wt%
Evaluation of Photoconductivity
samplesample
ITOITO
lightlight
ITOITOelectrodeelectrode
focusedfocused
collimatedcollimated
RR
HHVV
Typical I-V Curve
KeithleyKeithley source metersource meter
Photocurrent density as a function of applied voltage in devices with thesame proportion of PVK: pentacene (3:1) but various amounts of PbSesame proportion of PVK: pentacene (3:1) but various amounts of PbSenanocrystals as indicated in the legend.
Appl. Phys. Lett., 87, 051109 (2006) / US Patent 0128021 A1, 2008
Photocurrent density as a function of applied bias (1340 nm) indifferent devices with varying proportions of PVK and pentacene
The photocurrent increases significantly as the amount of pentacene in the composite increasesThe photocurrent increases significantly as the amount of pentacene in the composite increases.The best performance was extracted in devices with equal amounts of PVK and pentacene(having 25 wt % of PbSe QDs). The enhancement in photocurrent, compared to a PVK-PbSefilm, is over 8 times.
Comparison of the external quantum efficiency of the composite devices
2 % f S25 wt % of PbSe
Max EQE: Max EQE: ~ 8% in the IR~ 8% in the IR
A maximum external quantum efficiency (EQE) of ~8% at an applied device bias of 5 V is achieved in the composite having equal amounts of PVK and pentacene. This is an improvement of eight times over the PVK:PbSe devices under similar experimentalimprovement of eight times over the PVK:PbSe devices under similar experimental conditions.
QD-Carbon Nanotube / PVK Polymeric Nanocomposite
Carbon Nanotubes Coupled with Quantum Dots
SWCNT PbS QDSWCNT-PbSe QDs
SWCNT-CdSe
SWCNT CdSSWCNT-CdS
J. M. Haremza et al, Nano Lett. 2, 1253 (2002)
SWCNT-CdSe
S. Banerjee et al, Nano Lett. 2, 195 (2002)
I. Robel et al,Adv. Mater. 17, 2458 (2005)
QD-SWCNT-Polymer Nanocomposites for PhotovoltaicsPhotovoltaics
S A i h hi l AET
QD QDSH
H2N
SH
NH 2
HS
NH 2
HSNH
SHH2NAET
Spacer: Aminoethanethiol: AET
NH 2HS
NH 2
SH
NH 2
SHH2N
COOH
ligandexchange
COOH COOH
SWCNT
carboxylationCOOH
COOHCOOH
COOHCOOH
Dots
A variety of QDs active from UV to IR enables us to accessa wide part of the solar spectrum
b
10 nm10 nm
3 nm
2000
2500
1500si
ty (a
.u.)
1000
PL in
tens
0
500
1000 1100 1200 1300 1400 1500 1600
0
Wavelength (nm)
PL spectra of PbSe QDs (solid line) and SWNT-PbSe (dotted line)in tetracholoethylene colloidal suspensions. The concentration of y pPbSe QDs was the same in both cases.
I-V Characteristics of PbSe QD/PVK and SWNT-PbSe /PVK Devicein Dark and under Illumination
RR
HHVV
Keithley source meterKeithley source meter
b
Adv. Mater., 19, 232-236 (2007) / US Patent 2010-0025662 A1, 2011ACS “Heart Cut” Research Highlight, 2007
Contents
I d i- Introduction
Quantum Dot based Hybrids- Quantum Dot-based Hybrids * Enhancing the Photocurrent Density* Photopatternable Quantum Dots* Photopatternable Quantum Dots
- Low Bandgap PolymersLow Bandgap Polymers
- C60 Derivatives
- Summary
Surface Functionalization for Photo-Patternable QDs
OONH
OO
NH2hv with H+ catralyst
Chemical Amplification Reaction
D
NH
OOS
S
NH
OO
S
SHNS
HN
OO S
NHO
SS
NH2S
S
NH2S
SS
H2N S
H2N
SS
hv with H+ catralyst
ΔQD
QD
HN O
OHNO
O
SHN
OO NH2
H2N
SH2N
Se
Pb
Nano Lett., 8, 3262(2008)
Photocurrent Measurements of Photopatternable QDs
(a) 4
5
CdTe (t-BOC protected)CdTe (Deprotected)
2
3
rent
(nA
)
( p ) Dark
1
2
Cur
r
0 5 10 15 20 25 30 350
Electric Field (MV/m)(b)
Current-voltage curves (a) in the dark or with white light (100 mW/cm2) illumination for a film of t-BOCprotected and deprotected CdTe nanocrystals (measured at the voltage scan rate is 1 V/s). The channel lengthis 5 μm. MSM device structure (b) for photoconductivity measurement.
Polymer Nanocomposite Photovoltaics utilizing CdSe QDs Capped with a Thermally Cleavable Solubilizing Ligand
P3HT: CdS i
Al
PEDOT
P3HT: CdSe-amine
ITO
1.0
1.5
/cm
2 )
0 01
0.1
1
nsity
(mA
/cm
2 )
Solar Cell Device Structure
0.0
0.5
sity
(mA
/
0.0 0.2 0.4 0.6 0.8 1.0
1E-3
0.01
Cur
rent
den
Voltage (V)
1 0
-0.5
rent
den
s
100 oC (photo)100 oC (dark)
Thermal cleavage oft-BOC
0.0 0.2 0.4 0.6 0.8 1.0-1.5
-1.0
Cur
r 100 C (dark) 200 oC (photo) 200 oC (dark)
Voltage (V)Appl. Phys. Lett., 94, 133302 (2009)
OO
SiO
O O
O
Si
O
O
SiOSi
O
O
O
SiO
O
OS
SS
S
CdSe11
11
11
11
O
O
11
QD 1
UV: 552nm
PL: 568nm
3-D Lithographic Microfabrication
♦ Localized photochemistry by TPA process
C i PolymerizedCollimated Laser BeamPhotocurable film
Polymerizedregion
Objective lens
Focused beam
Lens
Single-photonpolymerization
Two-photonpolymerization
j
TPA : volume of order λ 3
Lens
TPA : volume of order λDOFLocalized photo-
polymerizationWidth
polymerization
Use of longer radiation wavelengths in TPA process is possible to achieve the better Use o o ge ad at o wave e gt s p ocess s poss b e to ac eve t e bettepenetration depth in the medium
S
SSPVDTT Flu PE
RR
N
RR
RR
RR
RR
RR
RR
RR
RR
R
RR
RR
N
SS
S
SS
NN
OC12H25
C12H25O
OC12H25
C12H25O
NBu2-DTTPE-NBu2 RRR
Polymers CeramicsNBu2-DTTPE-NBu2
MetalsMetals
CdSe/ZnSCore-Shell
CdSe
Figure (a) shows the photocuring of working acrylate functionalized quantum dots with its layer structure, (b) Shows the synthesis scheme for the acrylate functionalized photopatternable quantum dots.
Photopatterns by Using CdSe/ZnS Core-Shell QDsClli t dL B PolymerizedCollimated Laser Beam
L
Single-photonpolymerization
Two-photonpolymerization
Photocurable film
Polymerizedregion
Objective lens
Focused beam Size distribution of Nanorods: 10 -30 nm
TPA : volume of order λ3
Lens
DOFLocalizedphoto
Width
Localized photo-polymerization
Polymer Blocking Layer Effect on In2S3/CuInSSe Solar CellPEDOT:PSS
-5
0
5
2 ) -
eV
PEDOT:PSSBlocking the back recombination
-
-15
-10
-5
sity
(m
A/c
m2
+
-Ec
EF
-4
-5
-3
Au+
-
-25
-20
Cur
rent
Den
s
InS/CISSe/A
Ev
TiO In SCuInS2, CuInSe2
-6
-7
-8
Au
-0.1 0.0 0.1 0.2 0.3 0.4-35
-30C
Voltage (V)
InS/CISSe/Au InS/CISSe/PEDOT:PSS/Au
TiO2 In2S3 or CuInSSe
V is similarg ( )
Voc(V) Jsc(mA/cm2) FF(%) PCE(%)
Voc is similarJsc shows significant increaseFF is decreasedPCE increases due to the Jsc increment( )
w/o PEDOT:PSS ~0.26 18.4 35.3 1.69
with
PCE increases due to the Jsc increment
PEDOT:PSS effectively blocks electrons & transports holeswith
PEDOT:PSS ~0.29 33.5 31.9 3.16electrons & transports holes
Prasad et.al, 2009
Low-Bandgap Conjugated Polymersg p j g y
S S
NSN
nS
n
A
PCPDTBTn
P3HT
D-A concept Rigiospecific Structure
Optical Bandgap: 1.52 eV 1.90 eV
Low Bandgap Conjugated Copolymers: PFTB & PCTB
S S S
NS
N
S
PFTB PCTB
N
C8H17C8H17S
N
C8H17C8H17 NS
NS
C6H13
m n
R = C8H17: R1 = C6H13 n=0.1, m=0.9SR R R1 R1R Rn m
R = C8H17: R1 = C6H13 m=0.9, n=0.1S S S
C6H13l
n
Abs: λmax PL : λmaxAbs: λmax PL : λmax Abs: λmax PL : λmax521 nm 642 nm 519 nm (with PCBM 1:4) 643 nm (with PCBM 1:4)
Abs: λmax PL : λmax521 nm 642 nm 519 nm (with PCBM 1:4) 642 nm (with PCBM 1:4)
)
DeviceJsc Voc FF Solar Efficiency
2
-2
0
ent D
ensi
ty (m
A/c
m2
P3HT
I-V Characteristics and Solar Cell Efficiency
Device (mA/cm2) (V) (%) (%) P3HT/PCBM
(1:0.8) 4.234 0.485 49.68 1.02 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
-4Cur
r
Voltage (V)
P3HT PFTB:PCBM (1:4)
)
PFTB/PCBM3.596 0.881 37.64 1.19
(1:4) PCTB/PCBM
3 782 0 862 38 74 1 26-2
0
Den
sity
(mA
/cm
2 )
3.782 0.862 38.74 1.26(1:4)
-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
-4 P3HT PCTB:PCBM (1:4)C
urre
nt
Voltage (V)
Development of Efficient NIR Polymers;Synthesis of the Low bandgap Polymers
NSN NSN
SNSN
Synthesis of the Low bandgap Polymers
n
NS S
PFTTBTS S
NN
n
N SN
SSn
NS S
NS N
PFTTBBT
S S
NSN
nPCPDTBT
PCPDTBBT
0 30
0.35
PFTTBTPCPDTBT Optical properties of various polymers
0 20
0.25
0.30
(a.u
.)
PCPDTBT PFTTBBT PCPDTBBT Polymer Abs.
λmax. Opt. band
gap
PFTTBT 530 nm 1 98 eV
0 10
0.15
0.20
Abs
orba
nce PFTTBT 530 nm 1.98 eV
PCPDTBT 718 nm 1.52 eV
0 00
0.05
0.10A PFTTBBT 868 nm 1.19 eV
PCPDTBBT 950 nm 0.92 eV
400 600 800 1000 1200 14000.00
Wavelength (nm)
Comparison of UV-vis Absorption of Low Bandgap Polymers
BPCPDTBT (by Heeger’s group)
S S
S SBu3Sn SnBu3 Polymerization (Stille coupling)
NSN
NSN
SNSN
N NSBr
Sn
S BrPCPDTBBTB
2
PCPDTBT film PCPDTBT-PCBM blend film PCPDTBBT film N
SN
NSN
ce (
a.u.
) PCPDTBBT-PCBM blend filmSS
N
n
1
Abs
orba
nc 1100 nm
NS
PCPDTBBT (Our Work)
0
A
SS S S
NN
nN S
N
400 600 800 1000 1200 14000
Wavelenth (nm)
S
37
UV-vis absorption spectra of the PCPDTBT and PCPDTBBT Polymer films and the polymer-PCBM blend films
Contents
I d i- Introduction
Quantum Dot based Hybrids- Quantum Dot-based Hybrids * Enhancing the Photocurrent Density* Photopatternable Quantum Dots* Photopatternable Quantum Dots
- Low Bandgap PolymersLow Bandgap Polymers
- C60 Derivatives
- Summary
C60 Derivatives as Acceptors in Hybrid Bulk Heterojunction Solar Cells
PCBM
(A) (B)
Fig. (A) The contour plots of the HOMOs (left side) and the LUMOs, right side) of all investigated dyads.investigated dyads. (B) Electronic energy levels of an isolated dyads. Vertical arrows represent the most probable transitions (with oscillator strength higher than 0 1 Blue red andhigher than 0.1. Blue, red, and green arrows corresponds to the LE(F), LE(T), and ICT transitions, respectively.
Chem. Phys. Lett. 479 , 224 (2009) / Synth. Met. 159, 2539 (2009)
Electron Mobility of New n-Type C60 Derivative (Fu-Hexyl)
Encap glass
NS
S D
OSC
getterAl
Inkjet printing (0.5wt% Fu-Hexyl in chlorobenzene)
Fu-Hexyl
n+ SiGate (SiO2)
Mgchlorobenzene)
μ=0.028 cm2/V·s (0.0058 cm2/V·s for PCBM)
On-off ratio = 1.9 × 105
Org. Electron, 10, 1028 (2009)
Efficiency of ITO/PEDOT:PSS/P3HT:C60 Derivative/TiOx/Al Solar Cells
0
2
cm2 )N
S
-4
-2
sity
(m
A/c
-10
-8
-6
rren
t Den
s
P3HT:PCBM P3HT:C60-TH-Hx-3
P3HT:C60-TH-Hx-5
0.0 0.2 0.4 0.6 0.8-12C
ur
Voltage (V)
P3HT:C60-TH-Hx-5
Fu-Hexyl
Compounds Jsc (mA/cm2) Voc (V) FF Eff (%)
P3HT:PCBM 6.32 0.582 0.65 2.39
P3HT:C60-TH-Hx-3 6.58 0.575 0.64 2.44
Graphic Summary
Profs Paras N Prasad & Alex N Cartwright
Coworkers
Profs. Paras N. Prasad & Alex N. Cartwright Institute for Lasers, Photonics and Biophotonics, Univ. at Buffalo, SUNY, Buffalo, USA
Prof. Andrzej Graja j jPolish Academy of Sciences, Poznan, Poland
Prof. Tae-Dong Kim Dept of Advanced Materials Hannam Univ Daejeon KoreaDept. of Advanced Materials, Hannam Univ., Daejeon, Korea
Funding Agenciesg g
KRFKRF KOSEF AOARD / AFOSRSamsung Electronics