Collaborators R. Norwood, J. Thomas, M. Eralp,

S. Tay, G. Li , College of Optical Sciences,

S. Marder, Georgia Tech. M. Yamamoto, NDT Corp.

N. PeyghambarianUniversity of Arizona

College of Optical Sciences

Nanoengineered Organic Photonic Materials and Devices

Outline

Organic Nanostructures and Functional Composites

Electronic Transport in Organics and Comparison with Inorganics like Semiconductors

An Example: Photorefractive Polymers, Multi-color Sensitive Polymers

Optimization of Performance by electron transfer

Advantages of Organics: Large size Several ft2, light weight, ease of processing, inexpensive

Organic Nanostructures

Semiconductors OrganicsQuantum dots Molecules or polymers

21

1

RE gs

1000 1250 1500 1750 2000

R/R = 5 %

R = 4.7 nm

R = 3.4 nm

R = 2.7 nm

R = 2.2 nm

Ab

sorp

tio

n (

a.u

.)

Wavelength (nm)1000 1250 1500 1750 2000

R/R = 5 %

R = 4.7 nm

R = 3.4 nm

R = 2.7 nm

R = 2.2 nm

Ab

sorp

tio

n (

a.u

.)

Wavelength (nm)

R

(nm)

2

1

LEg

L

PbS

Example: Thin layer of PS/PMMA filmCourtesy: Nanosurf AG

0 10 20 30 40 50 60

Size of the molecule (A0)

N

N

O O

O

n

PATPD

N

ECZ

N

NCCN

7-DCST

C60

Molecules PATPD 7-DCST ECZ C60

Size(nm)

6 1.2 0.7 0.7PATPD MW=18,000Number of units = 28

Organic Nanostructures

Organic Nanostructures

Semiconductors OrganicsBand Structure HOMO and LUMO

Aj

Ai

Positional

Energetical

--

Hopping TransportBand Transport

2

0

( )exp( )exp

4 B

Ek k r

k T

Assembling Organic Nanostructures into Functional Composites for Applications

OLEDs Thin layers of pure material evaporated or

spin-coated

EO PolymerModulators

Organic Photorefractives

Application Assembly Nanostructures

Mixing of a structural polymer with a single functional component

Mixing of severalmultifunctionalcomponents

OCH3

O

p-MEH-PPV

n

PPV

N

N

PATPD

O

n

O

O

PATPDNC

CNN

7-DCST

Alq3

NO

O

OO

OO xy

NO

O

OO

OO

y

N

O

NCCN

CNF3C

O OSi Si

S

+

NO

O

OO

OO xy

NO

O

OO

OO

y

N

O

NCNCCNCN

CNCNF3CF3C

O OSiSi SiSi

S

+

AJ309

C60

a

b

c

d

e

D e p h a s i n g

T r a p p i n g

T r a n s p o r t

S p a c e

Photorefractivity in Polymer Composites

Convert an intensity distribution into a refractive index

distribution Sensitizer

Transport

Chromophore

Plasticizer

SLM

Beam-Splitter

ReferenceBeam

PR Polymer Film

ObjectBeam

Holographic Recording Reading

ReadingBeam

Observeror

CCD

Rewritable Holographic Recording and Display

Photorefractive Polymer Applications

Updatable 3D Display

Energetic and Electron Transport

Photorefractive Polymers (Guest Host Composites)

Chromophore

Transport

Photogeneration of carriers

Polymermatrix

Sensitizer

Electro-optic activity

Reducing Tg

Plasticizer

+ Low-cost, ease of fabrication and control over properties

- Bias Field

Transport matrix Chromophor

es

Vacuum level

5.9

5.4

N

( )

PVK

NN

O

O On

PATPD

(eV)

5.6

N

CNNC

DBDC

NCN

CN

7-DCST

C60

6.2

Plasticizer

ECZ

N

PATPD/ECZ/7DCST/DBDC/C60 – 633 nmPATPD/ECZ/7DCST/TNFDM – 845 nmPATPD/ECZ/7DCST/DBM – 975 and 1550 nm

Sensitizer

O2S

NC CN

N DBM

Molecular Energetics

C

CNCN

NO2 NO2

NO2

TNFDM

Linear Absorption

PATPD:7-DCST:APDC:ECZ:DBM / 49:25:25:10:1

500 600 700 800

0

100

200

300

400

500

Abso

rptio

n C

oeffic

ient (c

m-1)

Wavelength (nm)

PATPD:7-DCST:ECZ:C60 (54.5:25:20:0.5 wt.%)

600 800 1000 1200 1400 1600

0.0

0.5

1.0

1.5

2.0

980nm1550nm

775nm

Opt

ical

Den

sity

Wavelength(nm)

PR polymer sensitive for green to red

PR polymer sensitive to IR

Grating Writing and Reading

Thick-grating:

Typical values:= 633 nmd = 20 m~ 3 mQ= 2.3

2 12 sin2

n

2/ ndQ

1Q

2

K

x

z

1

2

‘2’

‘1’

V

signal

probe

Performance of PR Polymers

1E-3 0.01 0.1 1

0.0

0.1

0.2

0.3

0.4

0.5

Data: Data2_Ch2VModel: SinBiExp Chi^2 = 0.00009R^2 = 0.98978 A 0.50022 ±0.05239B 1.38797 ±0.29045t1 0.02713 ±0.00107t2 0.53958 ±0.20857m 0.65536 ±0.08449

effic

ienc

y (a

.u.)

time (s)

jt223-1.15kV

M. Eralp, et al, Opt. Lett, Accepted

Diffraction efficiency Response time

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0.0

0.2

0.4

0.6

0.8

1.0

Voltage (kV)

Int.

Diff

ract

ion

Eff

icie

ncy

jt163 jt223

-10 0 10 20 30 40 50 60 70 80

0

50

100

150

200

250

PATPD Sample@ 633nm

Gai

n,

(cm

-1)

Field (V/m)

Two Beam Coupling Gain

PATPD:DBDC:ECZ:C60 (49.5:30:20:0.5 wt.%)

0 10 20 30 40 50 60 70 800.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Beam 2

Beam 1

1, 2

Field (V/m)

Sensitizer Hole-transport Chromophore

h

Optimization of Photorefractive Polymers

N N

FF

N N

N N

OBu

OBu

BuO

BuO

N

BuO

BuO

N

OBu

OBu

N

BuO

BuO

N

OBu

OBu

Figure 1

1

2

3

4

5

Ip = 5.49 eVIp = 5.49 eV

Ip = 5.45 eVIp = 5.45 eV

Ip = 5.27 eVIp = 5.27 eV

Ip = 5.26 eV Ip = 5.26 eV

Ip = 5.35 eVIp = 5.35 eV

Polymer Composites:

Polystrene doped with TPD derivatives and C60

Polymer Composites:

Polystrene doped with TPD derivatives and C60

Tuning the IP of Transport Agents

5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0

1

10

100

F

A

B3C1

DE

Phot

ogen

erat

ion

effi

cien

cy (%

)

Ionization potential (eV)

Consistent with Marcus theory for electron transfer

As ionization potential of the transport agent increases, efficiency decreases

IP- Dependence of Charge Generation Efficiency

Marcus Theory for Electron Transfer

2

0

( )exp( )exp

4 B

Ek k r

k T

Hopping rate described as:

λ - reorganization energyβ – distance dependence

12 13 14 15 16 17 18 19

1E-3

0.01

0.1

E = 30 V/m

B4

B3

B2

B1

Ph

otog

ener

atio

n ef

fici

ency

(10-10

m)This follows the Marcus theory for electron transfer processes

Dependence of Charge Generation Eff. on Distance Between Hoping Sites

Performance of All PR Materials

Other GroupsUAZ

*P. Günter (Ed.), Nonlinear Optical Effects and Materials (Springer, NY, 2000) The dashed line connects points of equal sensitivity

Wavelength Sensitivity of PR Materials

Arizona

Operation at 532 nm

-10 0 10 20 30 40 50 60 70-20

0

20

40

60

80

100

CW-532nm DFWM Results (105m thick)

Int.

Diff

ract

ion

Effi

cien

cy,

(%)

Field (V/m)

32-1

Sample t1 t2 m

32-1* 25ms 1.6 s 0.54

• Over-modulation @ ~ 45 V/µm• 80-90% diffraction efficiency• Fast response time (25 ms t1)

* Irradiance: 1W/cm2 32-1: PATPD/FDCST/TPAAc/NF (48/40.6/11.9/0.5)

500 600 700 800

0

100

200

300

400

500

Abs

orpt

ion

Coe

ffici

ent (

cm-1)

Wavelength (nm)

0 20 40 60 80

0

20

40

60

80

100

Sample: PATPD:7-DCST:ECZ:C

60

(54.8:20:25:0.2)-JTDA08

Inte

rnal

Effi

cien

cy (

%)

Field (V/m)

Green Reading Red Reading

0 10 20 30 40 50 60 70 80 90-10

0

10

20

30

40

50

60

70

80

Sample: PATPD:7-DCST:ECZ:C

60

(54.8:20:25:0.2)-JTDA08

Inte

rnal

Diff

ract

ion

Efff

icie

ncy

(%)

Field (V/m)

Green Reading Red Reading

Grating Recorded by Red Laser

Grating Recorded by Green Laser

• Record two-color information of an object by writing with red and green lasers.

This polymer is sensitive at both 532 and 633nm

Absorption Characteristics (Two-color samples)

Two-Color Sensitive Devices

PATPD 7DCST ECZ C60

JTDA 08 54.8 20 25 0.2

Cool down naturally for 30s

V=0V=5kV

Reading with two writing beams blocked

Recording and readingat room temperature

CO2 laser beamOn for 2.5-3s

Thermal Fixing using CO2 Laser,0.5mm–Glass, CW Writing

CO2 laser can provide non-contact heating

Conclusions

500 600 700 800 900 100005

1015202530354045

Video Rate

DBM dyePATPD:TNFDM CT complex

NF/no sensitizer

C60

Wavelength (nm)

Res

pons

e T

ime,

t1

(ms)

500 600 700 800 900 10000

20

40

60

80

100 Internal External

Diff

ract

ion

Effi

cien

cy (

%)

Wavelength (nm)

Optimization of Photorefractive polymers Demonstration of PR polymers with excellent performance