Organic Electronics – Where Are We, Where Do We Go?

Organic Electronics – where are we, where do we go?

Karl Leo

Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden, Germany, www.iapp.de and Fraunhofer-COMEDD, 01109 Dresden

EDS Webinar, September 27, 2012 Outline

•Introduction

•What are organic semiconductors?

•Organic Light Emitting Diodes (OLED)

•Organic Solar Cells

•A few remarks on manufacturing

• Large area & flexible substrates possible • Large variety of materials • Low cost

Organic Organic light Photovoltaic Transistors materials emitting diodes cells and memory Future Markets for Organic Devices

• IdTechex study:

• 330 billion US$ in 2027

• Most important markets: - Logic/Memory - OLED-Display - Photovoltaics Progression of Organic Products

4th wave: Organic electronics 3rd wave: Solar cells

2nd wave: OLED lighting

1st wave: OLED Displays

Time Organic Light Emitting Diode (OLED) OLEDs: Basic Principles

LUMO Cathode E - A - - Cathode V Emissive layer Transparent anode Anode Glass substrate + + +

HOMO Light emission x Device structure Energy diagram

Organic materials needed: ≈ 1 g/m2 ! OLED display market forecasts – and the reality.. OLED display market forecasts – and the reality.. The 55‘ OLED TV is coming… Outline

•Introduction

•What are organic semiconductors?

•Organic Light Emitting Diodes (OLED)

•Organic Solar Cells

•A few remarks on manufacturing

Sp2-hybridised Carbon:

p -orbital p -orbital z π -bond z

plane of the σ-bond sp2-orbitals

π -bond

σ∗

π∗ pz pz π

sp2 sp2

σ Molecules with conjugated π-electron system

π-electron systems delocalize!

• VdW crystals • small π−π-overlap, narrow bands • saturated electron system delocalizeddelokalisierte π −Elektronen π-electrons

σ∗ π LUMO ( *) => EC „conduction band“ 6 x pz π HOMO ( ) => EV „valence band“

18 x sp2

Technology: vacuum evaporation Polymers with conjugated π-electron system

• broad bands • transport limited by interchain hops

n σ∗ π CB ( *) n x pz 6 x pz VB (π)

18 x sp2 sp2 Technology: solution processing Carbon: the influence of dimensionality

2D covalent broad bands 1D covalent: broad bands 104

Van der Waals- 101 coupling: 2D Narrow bands

1D 10-2

o 0D Source: Castro Neto, Geim et al.

m Band dispersion in vdW-coupled organics

• Dispersion from angle- resolved photoelectron spectroscopy

• Bandwidth 4t ≈ 200 meV: compare to exciton binding of about 500meV

• Agrees with mobility of 3.8cm2/Vs in broad band model

H. Yamane et al., Phys. Rev. B 68 (2003) 033102 Materials with low symmetry: packing is important

• Molecules often have comparably low symmetry

• Consequently, crystals have low- symmetry crystal class: Monoclinic or triclinic

• Disorder plays a big role Phthalocyanine-crystal Mobility as a function of disorder

• Rocking width correlates with mobility Typical OLED today!

• Even small disorder reduces µ strongly

• Conductivities are accordingly low

N. Karl et al. 2001 Growth of ordered layers: a challenge

QT (Quaterrylen) Directly on Au(111) on HBC on Au(111)

10 nm

reconstructed Au(111)-surface 1 ML HBC on Au(111): d = 3 Å

[ courtesy T. Fritz; R. Forker et al., Adv. Mat., 20, 4450 (2008) ] Outline

•Introduction

•What are organic semiconductors?

•Organic Light Emitting Diodes (OLED)

•Organic Solar Cells

•A few remarks on manufacturing

A n o d e O r g a n i c C a t h o d e A n o d e HTL EL ETL C a t h o d e

Φ E v a c - - A E s Φ - F - - - e V

I s

+ E F + + + + +

• Here: hole mobility larger than electron mobility => losses by holes reaching the cathode => losses by exciton quenching at the cathode => low outcoupling efficiency Electron and hole blocking layers

A n o d e O r g a n i c C a t h o d e A n o d e HTL EL ETL C a t h o d e

Φ E v a c - - A E s Φ - F - - - e V

I s

+ E F + + + + +

V • self balancing system => γ=1 • no exciton quenching by metal contacts • outcoupling can be optimized Achieve Carrier Balance: Blocking Layers

Five layer device: every layer optimized for specific function

X Al

e n

L t

o L

B i

T t

e m

H E

e l

H ITO E

• Small molecule OLED: balance easy for RGB, white more difficult • Polymer OLED: Balance more difficult to achieve Why doped layers: organic vs. Inorganic LED

Undoped Organic LED Inorganic LED (e.g., GaAs/AlGaAs)

ETL EFe Metal HTL p n i

EFh VB

• space charge limited currents • Flat-band under operation • low work function metals needed ITO-preparation necessary • Low work-function contacts not needed ! The pin-OLED structure

p i n r

e Cathode

k c

r o

l r

T n

o i

o H

B m

r -

t E

p c

l e

Anode l E

• Device operates in flat-band condition • Carriers are injected through thin space-charge layers P-doped ZnPc: Conductivity vs. Doping Concentration

T= 30°C

] ZnPc series 1 10-2 m ZnPc series 2 c / S [

y t

i -3 v

- i 10 t e c u d n

o linear dependence C 10-4 10-3 10-2 10-1 Molar Doping Ratio F -TCNQ : ZnPc 4 Nominally undoped ZnPc: ≈10-10 S/cm ⇒ Doping increases conductivity by orders of magnitude

M. Pfeiffer, A. Beyer, T. Fritz, K. Leo, Appl. Phys. Lett. 73, 3202 (1998); K. Walzer, B. Maennig, M. Pfeiffer, K. Leo, Chem. Rev. 107, 1233 (2007) Thickness of space charge layers

• MeO-TPD doped with F4-TCNQ

• Sparge-charge layer thickness scales with dopant density

• Few monolayers for high dopant density

S. Olthof et al. J. Appl. Phys. 106, 103711 (2009) The most simple device: pn homo junction

Al ZnPc - homo ( d = 30 nm ) 1x10-1 i

-2 40 nm n-ZnPc 1x10 Al n - ZnPc )

-3 i-ZnPc 2 1x10 i - ZnPc 30 nm p - ZnPc

m -4

c 1x10 15 nm p-ZnPc / ITO A

(

-5

y 1x10 24.0 °C t ITO i s -1.8 °C n -6 e 1x10 -26.6 °C D

n -7 -42.6 °C e 1x10 r

r -58.7 °C u

C 1x10-8 -82.8 °C

1x10-9 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 Voltage ( V )

ZnPc: K. Harada et al., Phys. Rev. Lett. 94, 036601 (2005); Pentacene: K. Harada et al., Phys. Rev. B 77, 195212 (2008) Where ist the voltage limit: Results for thermodynamically ideal device

1E8 1E8 1E7 1E7 1000000 1000000 100000 100000 2 10000 10000 • At 100Cd/m : ) 2 1000 1000 only about 20% red: 1,56V m / 100 100 excess voltage over d green: 1,95V C

(

10 10 theoretical limit

e blue: 2,28V c

n 1 1 a n i 0,1 0,1 m u

L 0,01 0,01 • Voltages at high 1E-3 1E-3 brightness can still be 1E-4 1E-4 improved! 1E-5 1E-5 0,0 0,5 1,0 1,5 2,0 2,5 Voltage (Volt) Best value for red: R. Meerheim et al., Proc. SPIE 6192, 61920P/1 (2006) 1.89V (Novaled) The all-organic device: Red pin OLED at 2.4V

Best devices: 1.89V ≈ thermodynamic limit + 20% What determines OLED efficiency? hν η = b × ×η ×η external I eU recomb optical Recombination efficiency

√ • bI: Electron and hole current balance: 1 can be reached

• eU: Operating voltage should be ≈ photon energy √

∀η recomb: 75% Triplet, 25% Singlet excitons: 0.25 for fluorescent emitter: Use phosphorescent emitters (Forrest/Thompson), optimize recombination zone √

∀η optical: about 20% in flat structure: 80% lost to wave guide modes Spin Statistics: Phosphorescent Emitters are needed (Thompson & Forrest)

hole electron exciton Ir(ppy)3 + Triplet

+ Triplet Ir N + Triplet 3 + Singlet Phosphorescent

Emitter: Ir(ppy)3

• e-h-recombination: 75% triplet- and 25% singlet-excitons • Phosphorescent emitters: triplets are used as well due to spin-orbit coupling by heavy metals (Ir, Pt, Cu…) • ≈ 100% internal quantum efficiency reached What determines OLED efficiency? hν η = b × ×η ×η external I eU recomb optical Outcoupling efficiency

• √ bI: Electron and hole current balance: 1 can be reached

• eU: Operating voltage should be ≈ photon energy √

∀η recomb: 75% Triplet, 25% Singlet excitons: 0.25 for fluorescent emitter: Use phosphorescent emitters (Forrest/Thompson), optimize recombination zone √ ∀η optical: about 20% in flat structure: 80% lost to wave guide modes Distribution of Power in Modes

• Outcoupled modes • Substrate modes (1) • Organic modes (2) • Plasmonic losses (3) Substrate Modes: Outcoupling easily achieved

Source: Temicon Optical Simulation: The Model

• Emitter is treated as electrical dipole • Power spectrum K is calculated by a transfer matrix approach • Isotropic orientation of molecules is Mauro Furno assumed • Total emitted power by the dipole is Ag given by n

∞ ∞ 2 F(λ) =∫ K(λ,u)du = 2∫ uK(λ,u)du p 0 0 ITO

Low-n (LI) glass

[1] W.L. Barnes, J. Mod. Opt. 45, 661 (1998)) [2] M. Furno et al., Phys. Rev. B 85, 115205 (2012) Waveguide Modes

Glass

ITO

Organics

M. Furno et al. Cathode

Emitting Center Surface Plasmon Modes

Glass

ITO

Organics

M. Furno et al. Cathode

Emitting Center High Losses due to Coupling to Metal! Distribution of power into different modes

• Calculations by Mauro Furno (M. Furno et al. Proc. SPIE 7617, 761716 (2010); Phys. Rev. B 85, 115205 (2012))

• Model includes Purcell effect

• Model can be tested by variation of electron transport layer thickness

R. Meerheim et al., Appl. Phys. Lett. 97, 253305 (2010) Bottom-emitting OLED with high-index substrate

• High-Index Substrates: no index step at substrate- OLED interface

• Surface plasmons can be suppressed by thick ETL

• Absorption is largest optical loss

R. Meerheim et al., Appl. Phys. Lett. 97, 253305 (2010) Experiment: High Index Glass

Ag (100) Bphen (x) Cs BAlq (10)

NPB:Ir(MDQ)2(20) Spiro-TAD (10) MeO-TPD (36) NDP-2 ITO (90)

High-n (HI) glass

R. Meerheim et al., Appl. Phys. Lett. 97, 253305 (2010) Experiment: High Index Glass

Ag (100) Bphen (x) Cs BAlq (10)

NPB:Ir(MDQ)2(20) Spiro-TAD (10) Up to 54 % EQE (104 lm/W) were reached for red OLEDs MeO-TPD (36) NDP-2 ITO (90)

High-n (HI) glass

R. Meerheim et al., Appl. Phys. Lett. 97, 253305 (2010) All-phosphorescent white OLED

• S. Reineke et al., Nature 459, 234 (2009) • Novel emitter layer design • High-index substrate and higher-order electron transport layer Results for White OLED

Ag ETL

HTL ITO

High-nLow-n (LI)(HI) glassglass

S. Reineke et al., Nature 459, 234-238 (2009) Results with high-index thin films Results with high-index thin films

• Extremely high quantum and power efficiency • Approach not yet proven for white

• Z.B. Wang et al., Nature Photonics 5, 753 (2011) Realistic Efficiency Goal for White OLED

• Internal efficiency close to 100%

• Low voltage

• Outcoupling about 60%

• About 150 lm/W are possible! Outline

•Introduction

•What are organic semiconductors?

•Organic Light Emitting Diodes (OLED)

•Organic Solar Cells

•A few remarks on manufacturing

• Flexible plastic substrates and thin organic layers • Low material and energy consumption • Short energy payback time • Potentially transparent, color adjustable • Compatible with low-cost large-area production technologies

Images: Konarka, Neuber, Heliatek, IAPP Organic Solar Cells – where is the Market?

• „Window of opportunity“ in power market: 2015-2030

• What is needed: 10-12% in module = 15-17% in lab OPV • Lifetime at least 10 years

Classes of Organic PV

Polymer/small-molecule heterojunction Dye-sensitized solar cell

Hybrid organic- inorganic The exciton separation problem

• Absorption leads to tightly bound (0.2 … 0.5 eV) excitons

• Separation in electric field inefficient

• Usual solar cell structure does not work

S. E. Gledhill et al. J. Mat Res. 20, 3167 (2005) P. Würfel, CHIMIA 61, 770 (2007) The exciton diffusion length problem

• Exciton diffusion lenghts are usually be small: ≈ 10 nm

• Much higher values have been reported for materials with higher order

• Possible workaround: use triplet diffusion: so far not successful The key element: donor-acceptor heterojunction

Flat heterojunction (FHJ) bulk heterojunction (BHJ)

a n o d e c a t h o d e a n o d e c a t h o d e ( e . g . I T O ) ( e . g . A l )

d o n o r a c c e p t o r

C. W. Tang, Appl. Phys. Lett. 48, 183 (1986) M. Hiramoto et al., Appl. Phys. Lett. 58, 1062 (1991) J. J. Hall et al., Nature 376, 498 (1995) G. Yu et al. Science 270, 1789 (1995) New Small Molecule Absorber Materials

• Benzoporphyrins: Y. Matsuo et al., J. Am. Chem. Soc. 131, 16048 (2009)

• Squaraines: F. Silvestri et al, J. Am. Chem. Soc. 130, 17640 (2008); G. Wei et al., ACS Nano 4, 1927 (2010)

• Merocyanines: N. Kronenberg et al., J. Photon. Energy 1, 011101 (2010)

• Bodipys: T. Rousseau et al., Chem. Comm. 1673 (2009), R. Gresser et al., Tetrahedron 67, 7148 (2011)

• Thiophenes: K. Schulze et al., Adv. Mat. 18, 2872 (2006); Y. Sun et al., Nature Mat. 11, 44 (2012) Solution processed record efficiencies

• Y. Sun et al., Nature Mat. 11, 44 (2012)

• 6.7% photoconversion efficiency

• 180nm active layer thickness! The p-i-n Concept for Organic Solar Cells

F4-TCNQ AOB N F F N

N F F N 4P-TPD C60

Cathode

Di-NPD n-doped ETL n N N N N Zn N ZnPc Photovoltaic N N i active Layer N

Bu Bu Bu Bu

S S S p-doped HTL CN CN p S S CN CN DCV5T-Bu Anode 2-TNATA B. Maennig et al., Appl. Phys. A 79, 1 (2004) M. Riede et al., Nanotechnology 19, 424001 (2008) Small Molecule Organic Solar Cell Materials •• donor-acceptor pair for photoactive layer

N ZnPc: optical gap

N N ~ 1.55eV N Zn N N N UOC ≈ 0.5V N C 60 ZnPc •• acceptor: p-dopant •• hole transport layer N F F N CH 3 MeO MeO F4-TCNQ

N F F N N N

N N N H3C

H3C N MeO MeO donor - precursor: n-dopant m-MTDATA MeO-TPD •• donor - precursor: n-dopant

•• electron transport layer O / Cl- CH 3 + N O N O N O Rhodamine B

C60 O N O CH 3 PTCDI Exciton separation: energy loss at the donor-acceptor heterojunction

Example system: ZnPc/C60

ZnPc Open circuit voltage: ≈0.5V Abs. edge: 1.6eV ⇒Large loss of energy 4.3 4.0 EQF,e Uoc=0.5V 4.8 EQF,h Minimum energy loss 5.1 upon charge separation: 0.2….0.7 eV?

C60 Low gap thiophene oligomers

DCV1T

University of Ulm Department Organic DCV3T Chemistry II

DCV4T E.Brier, E. Reinold, P. Kilickiran, P. Bäuerle DCV5T

DCV6T

DCV7T Low gap thiophene oligomers: transport levels

DCV3T DCV4T DCV5T DCV6T -3.0

-3.5 LUMO -4.0

V 1.80 eV

1.90 eV

/ -4.5 2.03 eV

g 2.12 r -5.0 eV

e -5.5 HOMO -6.0

-6.5

CV, onset CV, peak-to-peak: UPS fullerene C60 C. Uhrich et al., (UPS/IPES) in CH2Cl2/TBAPF6 D'Andrade et al., submitted to Adv. Funct. vs. Fc/Fc+ (-4.8eV) Org. Electr. 6 (2005) 11 N. Sato et al., Mater. Chem. Phys. 162 (1992) 433 E. Brier, P. Bäuerle et al., K. Schulze et al., in preparation R. W. Lof et al., Adv. Mater. 18 (2006) 2872 Phys. Rev. Lett. 68 (1992) 3924 Solar Cells with DCVnT

10 Open circuit voltage Charge carrier separation efficiency ) 2 fill factor FF m 0 c saturation factor j j

/ (-1V)/ SC

m DCV4T ( Voc = 1.13 V FF = 27.6%

j -10 j(-1V)/jsc = 1.32 10 )

m 0 c /

A Voc = 1.00 V FF = 50.4%

m DCV5T ( -10 j(-1V)/jsc = 1.10

j 10 )

m 0 Voc = 0.93 V FF = 49.7% c / j(-1V)/jsc = 1.15 A m

( DCV6T

j -10 decreases increases -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 voltage [V] with increasing chain length

ITO / Au(1) / pTNATA(30) / pNPD(10,4:1) / NPD(5) / DCVnT (8) / C60 (40) / Bphen(6) / Al(100) Minimum HOMO-LUMO difference: approx. 0.3eV Comparison DCV5T vs. ZnPc: Double Voltage

ZnPc / C60 118 mW/cm2 white light ) 5 DCV5T 2 Uoc = 0.49 V ZnPc m jsc = 10.1 mA/cm²

c C / FF = 55 % 60 C60 A 0 η = 2.3 % m (

y t

i ADA-BCO 2 / C DCV5T/C60 60 s -5 2 n 118 mW/cm white light e U = 0.98 V d oc

t jsc = 10.57 mA/cm² n

e -10 FF = 48.5 % r

r η = 4.26 % u η = 3,4% c -15 -1.0 -0.5 0.0 0.5 1.0 voltage (V)

K. Schulze et al., Adv. Mater. 18 (2006) 2872 New Thiophenes: DCV5T-Me Series

H3C CH3 H3C CH3

S S S S S NC CN CN NC 1: DCV5T-Me(1,1,5,5)

S S S S S NC CN CN NC H3C CH3 H3C CH3

2: DCV5T-Me(2,2,4,4)

H3C CH3

S S S S S NC CN CN NC 3: DCV5T-Me(3,3)

University of Ulm R. Fitzner et al., submitted (2012) Department Organic Chemistry II DCV5T-Me Results

NDP9 (1) Au (50nm)

p-BPAPF 10wt% (50nm)

BPAPF (5)

DCV5T-Me 1-3:C60 (2:1, 90°C, 30) I # V (V) SC FF Eff.(%) OC (mA/cm2) C (15) 60 1 0.91 9.6 62.5 5.5

glass + ITO 2 0.95 9.4 62.1 5.6 3 0.96 11.1 65.6 6.9

University of Ulm Main effect: subtle dependence of crystal Department Organic Chemistry II size in BJH on molecular structure Covering the full solar spectrum

• Much of the solar spectrum is currently not used!

Extend absorption to IR Tandem or triple cells

M. Hiramoto et al., Chem. Lett. 1990 (1990) 327; A. Yakimov & S.R. Forrest, Appl. Phys. Lett. 80 (2002) 1667 Pin-tandem cells: doped layers are critical for optical optimization

p-i-n tandem cells: n - • Pn-junction is ideal photoactive layer 2 recombination contact p +

n - • optimizing interference pattern with photoactive layer 1 conductive transparent layers p + substrate foil =>optical engineering on nanometer layer thickness scale

J. Drechsel et al., Appl.Phys.Lett. 86, 244102 (2005) Pin-tandem cells: placing absorbers in different field maxima

Thickness of spacer layer

0 nm (1st m ax.)

74nm (1st m in.)

124nm (2nd m ax.)

R. Schüppel et al., J. Appl. Phys. 107, 044503 (2010) Pin-tandem cells: placing absorbers in different field maxima

R. Schüppel et al., J. Appl. Phys. 107, 044503 (2010) Importance of Efficient Recombination contact

Good junctions Bad junction

• Recombination contact must be „bad“ solar cell: Open-circuit voltage should be zero • Highly doped pn-junction is ideal solution: tunneling through narrow space charge layer (S. Olthof et al., J. Appl. Phys. 106, 103711 (2009), R. Timmreck et al., submitted) Efficient Recombination Contact

•Metal clusters have only weak effect on efficient recombination

•Highly doped pn- junction is very efficient, stable and simple recombination contact

R. Timmreck et al., J. Appl. Phys. 108, 033108 (2010) Small-Molecule OPV Record > 1cm²

8.3 % on 1.1cm² certified by Fraunhofer ISE, Germany

Latest Heliatek Result: 10.7% certified by SGS Fresenius

8.3 % on 1.1cm² certified by Fraunhofer ISE, Germany

)

(

diagram available under www.orgworld.de Organics is more: The O-Factor

• Standard measurement: 1 sun, 25 0C, perpendicular incidence

• Reality: 40-60 0C, often less than 1 sun, diffuse light

• Organics: – Positive temperature coefficient – Higher efficiency for lower intensity – Special diffuse light responsivity

• Sums up in the O-Factor: approx. 30% better! Incident Angle Performance

High independence on incident • Heliatek Absorber • Certified Efficiency: 8.3 % (1 angle: cm2) Efficiency development from 0 to 60° • Collaboration of Heliatek und above the expected values of pure IAPP (TU Dresden) geometrical consideration

Superior low-light performance: • Heliatek Absorber • Certified Efficiency: 8.3 % (1 97 % of full-sun efficiency at 1/10th cm2) sun • Collaboration of Heliatek und IAPP (TU Dresden)

Power conversion efficiency of a tandem cell (in %)

0 2.000 4.000 6.000 3.5 8.000 V e 10.00

l 12.00 l e 14.00 c 3.0 d 16.00 n 18.00 o c 20.00 e s

22.00 f 2.5 o y g r e n e 2.0 p a

g first cell second cell l a c i r t 1.5 c

e e.gap 1.9eV 1.25eV ~21% l e o.gap ~770nm ~1300nm 1.0 1.5 2.0 2.5 3.0 3.5 e.gap 2.1eV 1,5eV ~20% electrical gap energy of first cell / eV o.gap ~690nm ~1030nm

e.gap 2.225eV 1.7eV ~19% o.gap ~645nm ~890nm T. Mueller et al. Dependence of degradation on photocurrent

• Degradation is directly proportional to photocurrent

M. Hermenau et al., Solar EnergyMaterials&SolarCells 95, 1278 (2011) Recent degradation study: water and oxygen

• M. Hermenau et al. Solar En. Mat. & Solar Cells 95, 1268 (2011) Results of degradation study

• Mainly current and FF

degrade; Voc is rather stable

• Water is much more relevant than oxygen

– Water leads to oxidation of Al electrode

– Water induced ZnPc degradation

M. Hermenau et al. Solar En. Mat. & Solar Cells 95, 1268 (2011) Lifetime of Thiophene Tandem Cells

• Collaboration between Heliatek & IAPP • Absorber materials from BASF and Heliatek, dopants from Novaled • Glass-glass encapsulation • Halogen light at about 1.5 suns Stress Device Integrated Corresponding Conditions Temperature Light Dosis Exposure Time in Middle Europe 50°C 8.1 MWh/m² 8 y

85°C dark Outline

•Introduction

•What are organic semiconductors?

•Organic Light Emitting Diodes (OLED)

•Organic Solar Cells

•A few remarks on manufacturing

linear organic source modules linear ion source

Substrate roll protective sheet

RF-DC-Magnetron port to glove box for inert substrate Metal evaporator module handling (two metal sources)

deposition cylinder

winding units

attachement possibility for a glove box

Electrical tests in the inert box

Electrical tests after the encapsulation

top emitting OLED on metal sheets

Transparent OLED on Polymer web

• New Master program „Organic and Molecular Electronics“

• Starting in fall 2012

• Industry grants available

• www.tu- dresden.de/physik/ome Conclusions

• Organic Semiconductors: • Advantages: Flexible, Low Cost, … • But: Low mobility and stability

• Organic Light Emitting Diodes have shown excellent performance

• Organic Solar Cells: still a long way to go

• Manufacturing technologies still rather immature Acknowledgment

• S. Reineke, S. Hofmann, S. Pfützner, H. Ziehlke, C. Körner, T. Menke, T. Müller, L. Burtone, D. Ray, C. Elschner, J. Meiss, M. Furno, C. Sachse, L. Müller-Meskamp, M.K. Riede, B. Lüssem, J. Widmer, M. Hummert, M. Gather (IAPP) • K. Fehse C. May, C. Kirchhof, M. Toerker, M. Hoffmann, S. Mogck, C. Lehmann, T. Wanski (FhG-IPMS) • J. Blochwitz-Nimoth, J. Birnstock, T. Canzler, S. Murano, M. Vehse, M. Hofmann, Q. Huang, G. He, G. Sorin (Novaled) • M. Pfeiffer, B. Männig, G. Schwartz, K. Walzer (Heliatek) • J. Amelung, M. Eritt (Ledon) • D. Gronarz (OES)

• R. Fitzner, E. Brier, E. Reinold, P. Bäuerle (Ulm) • D. Alloway, P.A. Lee, N. Armstrong (Tucson) • U. Zokhavets, H. Hoppe, G. Gobsch (Ilmenau) • K. Schmidt-Zojer (Graz), J.-L. Bredas (Atlanta) • R. Coehoorn, P. Bobbert (Eindhoven) • T. Fritz (Jena) • M. Felicetti, O. Gelsen (Sensient) • A. Hinsch, A. Gombert (ISE) • D. Wöhrle (Bremen), J. Salbeck (Kassel), H. Hartmann (Merseburg/Dresden) • C.J. Bloom, M. K. Elliott (CSU) • P. Erk (BASF) and others from OPEG • BMBF, SMWA, SMWK, DFG, EC, FCI, NEDO We are looking forward to a cooperation

Prof. Dr. Karl Leo Institut für Angewandte Photophysik Technische Universität Dresden 01062 Dresden, Germany ph: +49-351-463-37533 or mobile: +49-175-540-7893 Fax: +49-351-463-37065 email: [email protected] Web page: http://www.iapp.de