Scientific and Technological Progress with

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Scientific and Technological. Progress with Polyaniline and. Poly-ethylenedioxythiophene. Dr. Bernhard Wessling. Ormecon Chemie, FRG. Nanotechnology at ...
Dr. Bernhard Wessling Ormecon Chemie, FRG

Scientific and Technological Progress with Polyaniline and Poly-ethylenedioxythiophene Nanotechnology at its Best

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Need of a HIL Cathode: Ba, Ca, Al

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Light Emitting Polymer (LEP)

anode: ITO carrier: glass

electron

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h*

light

recombination

hole

injection barrier: difficult hole transport into LEP layer / level of work function; rough topology; impurities higher operating voltage necessary poor lifetime values

Previous attempts to HILs with PAni “solutions”

 short shelf life because of gelation and particle aggregation  very poor reproducibility even on laboratory scale  conductivity too high => cross talk problems  expensive and toxic components  thin films with high surface roughness  not filterable with nanopore filters

New PAni Dispersions for HIL requirements:  environment friendly medium => water  nanoscale particle size (< 80 nm)  low conductivity (< 10-5 S/cm) to avoid cross talk  tunable work function to improve HI  tunable viscosity (appropriate for each application technique)  reproducible properties  commercial scale

stable device performance and improved lifetime

Particle Size Distribution AFM / EFM: Laser Doppler Measurement: PAni PA T 010, av = 35 nm 24 PEDT CH8000, av = 20022nm PEDT 4083, av = 400 nm

24 22

parts [% ]

20

20

18

18

16

16

14

14

12

12

10

10

8

8

6

6

4

4

2

2

0 1E-3

0 0,01

0,1

1

10

Particle size [µm]

=> particle size distribution stable > 12 months => surface roughness < 10 nm

OLED with PAni-HIL

on glass, with a performance increase of 5 - 27% vs PEDT

Passive Matrix Displays avoid cross-talk between dots

conductivity < 10-5 S/cm

2-point probe measurements on coated ITO substrates

COVION

EIS

glass

ITO glass

Resistance • coating thickness = specific conductivity

Conductivity measurement on the real HIL layer, as if in OELD

Fourier Transformation Impedance Spectroscopy

Conductivity Measured under Vacuum => accelerate equilibration time for HIL

COVION HIL PAT 010 PEDT 4083 EL PEDT CH 8000

Cond. [S/cm] 2,2*10-6 1.5*10-1 8,8*10-6

HIL PAT 010 PEDT 4083 EL PEDT CH 8000

Cond. [S/cm] 7,0*10-7 1.5*10-1 1.5*10-5

Customer’s requirements for cond. < 10-5 S/cm fulfilled with PAni PAT010

Work Function measurement with the Kelvin Probe

Work function in correlation with device performance optim um range ITO P Ani sam ple < 100 %

P Ani sam ple = 100 % P Ani sam ple > 100%

PE DT CH8000 PED T 4083EL

HOMO: by CV

SuperY ellow

4,2 4,3 4,4 4,5 4,6 4,7 4,8 4,9 5,0 5,1 5,2 5,3 5,4

work function [eV]

optimum for hole injection: wf = - 4.85 - 4.95 eV