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Organic Electronics

R. Österbacka,

Department of Physics Åbo Akademi University

http://www.abo.fi/fak/mnf/fysik/

(2)

Our goal

To understand the electro-optical properties of disordered organic materials to be able to demonstrate

novel devices

(3)

To achieve the goals:

Optical Optical

spectroscopy spectroscopy

Transport Transport studies studies

Novel Novel devices devices

To achieve the goals we have specialized in the

following:

Transport studies using novel transient techniques

Electro-Optical

characterization of disordered

organic materials

(4)

Towards printed organic electronics

Active electronic components on plastic or fiber based materials

Novel device concepts needed!

– Solution processable – Simple design

– Linewidths of >10 μm, avoid critical alignments etc – Recyclable or disposable

All components needed for stand-alone operation

– Power supplies, transistors, memories, output

Low-voltage operation needed

Plastic electronics will never replace Silicon!

(5)

What have we done?

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1) Plastic Solar Cells

http://www.konarkatech.com

A. Pivrikas, Phys. Rev. Lett., 94 176806 (2005) G. Juska et al., Appl. Phys. Lett. (2005)

A.J. Mozer et al., Phys. Rev. B, B, 72, 035217 (2005)

The goal is to understand The goal is to understand transport

transport and recombination and recombination of photogenerated charge of photogenerated charge carriers

carriers Today η >5%

Partner V

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1) Plastic Solar Cells

Organic materials have low mobility leading to higher carrier density!

Higher density leads to lower carrier lifetime -> Lower current!

We have shown that recombination can be reduced with a factor of 10 000!

Reason is the carrier delocalization on the nano-scale!

A. Pivrikas, et al., Phys. Rev. Letters, 94 176806 (2005) R. Österbacka et al., Science 287, 839 (2000)

E en

j = μ

n= carrier density μ = carrier mobility e= electron charge E=electric field

Partner V

Efficiency proportional to current

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2) Polymeric transistors

Replacing inorganic materials with polymeric

Performance change with materials and processing

T.G. Bäcklund et al. Synthetic Metals, 148:87-91, 2005.

(9)

Hygroscopic Insulator FET

0 -1 -2

0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4

VG= -0,8 V

- 0,6 V

- 0,4 V - 0,2 V 0 V + 0,2 V

I

SD

[ μ A]

V

SD

[V]

0 -5 -10 -15 -20 -25 -30

0.00 -0.05 -0.10 -0.15

-10V -15V -20V -25V VG= -30V

I SD[μA]

VSD [V]

Traditional OFET HIFET

H. G. O. Sandberg et al. Advanced Materials 16, 1112 (2004) Finnish patent FI20031435, PCT application filed by Avantone

Using the hygroscopicity we could:

-Lower drive voltages (<1/10) -Enhance the current levels (>10)

Partner V

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Device model

T. Bäcklund et al., J. Appl. Phys., 98, 074504 (2005)

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3) Novel memory device

-8 -6 -4 -2 0 2 4 6 8

1E-11 1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1

C u rrent dens it y (A/ c m

2

)

Voltage (V)

7.5%

5%

1%

~10

3

V

Write

H. Majumdar et al., Org. Electronics Letters, 6, 188 (2005)

Single layer nano-composites of fullerenes and polystyrene gives us a solution-processable memory device!

C60 fullerene

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How it works as a memory

Current

Erase Write

ON OFF

Voltage

Read

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4) Polymeric spin-valve

S. Majumdar, et al., APL 89, 122114 (2006).

-300 -200 -100 0 100 200 300 4

5 6 7 8

T = 5K

Down sweep Up sweep

B (mT)

R (MΩ)

Spin Valve Open Current High

Ferromagnetic Electrode 2 Ferromagnetic Electrode 1

Spacer layer

Spin Valve Close Current Low

Future electronics?!

-300 -200 -100 0 100 200 300 107.5

108.0 108.5 109.0 109.5 110.0 110.5 111.0

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0

R (KΩ)

B (mT)

T = 300K

%MR

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Functionalisation

Functional Coatings (Phys Chem) Functional binders/Modifiers(PT) Functional polymers (PChem/HU)

Substrate manufacturing (PCL)

Functional Substrate

Sensor&Device Assembly (Phys) Sensor & Device Printing (FunPrint)

FunMat

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Planar International Ltd for patterned ITO

Financial support from Academy of Finland and TEKES

H. Aarnio, J.K. Baral, M. Berg, T. Bäcklund, H. Majumdar, S. Majumdar, A. Pivrikas, M. Westerling, K.-M. Källman, and H. Stubb, Åbo Akademi Univ.

A. Ivaska, J. Bobacka Department of Analytical Chemistry, Åbo Akademi Univ.

R. Laiho, Wihuri Physical Laboratory, University of Turku O. Ikkala, Center for New Materials, HUT, Finland

H. Sandberg, VTT/Polymer electronics

G. Juska, K. Arlauskas, K. Genevicius, G. Sliauzys, and M. Viliunas, Dept. of Solid State Electronics Vilnius University, Lithuania

A.J. Mozer, G. Dennler and N.S. Sariciftci, LIOS, Johannes Kepler University, Linz, Austria M. Scharber, Konarka, Linz Austria

Z.V. Vardeny, Dept. Of Physics, University of Utah

V. Sundström, A. Yartsev, K. Jespersen, T. Kesti, Lund Laser Center, Lund University, Sweden M.R. Andersson, Chalmers University, Sweden

O. Inganäs, Biomolecular and Organic Electronics, Linköping University, Sweden M. Berggren, N. Robertson, Organic Electronics, Linköping University, Sweden

Acknowledgements

Viittaukset

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