(Chemical vapour deposition usually not applied.)
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
16
Thin Film Deposition
• from the gas phase, i.e. by evaporation or sublimation applicable to low-molecular weight materials only
– Thermal evaporation in high or ultra-high vacuum – Organic molecular beam deposition / epitaxy (OMBD / OMBE) in HV / UHV (Epitaxy: lattice-matched growth on single-crystalline substrates)
Fullerene C60
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b) Conjugated Polymers
R
R
n
Polyfluoren (PFO)
Polyvinylcarbazole (PVK)
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
7
sp2 Hybridisation and Double Bonds
Molecular backbone by σ-bonds Electronic excitations between π and π* orbital (UV or visible range)
σ*-orbital
π-Orbital
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Vacuum Deposition
Thermal Evaporation
Substrat Maske Schwingquarz
Organic Molecular Beam Deposition
Verdampfer (”Boot”) W, Mo, Ta
Organ. Material
Strom
Tiegel (PBN, Quartzglas) Heizung
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
5
2) Materials
Molecular Orbitals and π-Bonding
Cu-Phthalocyanine Tris-(8-hydroxyquinoline) Triphenyldiamine (CuPc) (Alq3) (TPD)
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
Anthracene (C14H10)
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
11
Material Classes: a) Low-Molecular Weight Materials
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3) Preparation
Purification and Crystal Growth
Temperature gradient sublimation
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
9
Aromatic Hydrocarbons
e.g. Anthracene (C14H10)
• • (in-phase) overlap of atomic orbitals bonding molecular orbitals E.g. H2-molecule
•
σ and π-bonds:
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
Introduction to Materials Science Analysis Methods
Organic Semiconductors – Thin Film Preparation and Characterisation
Part I: Materials and Film Deposition
15
Purification and Crystal Growth
Temperature gradient sublimation
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
8
Delocalisation of π-electrons
linear systems: alkenes, polymers
Conjugated π-electron system
aromatic systems: e.g. benzene
PPV
Polyphenylenevinylene
1.12.2005
•
from solution: applicable to polymers and low-molecular weight materials (sometimes in a polymer matrix „blending“)
– – – – – Spin-coating Doctor-blading Printing Langmuir-Blodgett technique Self-assembly / Dip-coating
4
Device Physics of Organic Semiconductors
Ongoing research in chemistry, physics and engineering Regular course: “Physics of Organic Semiconductors” (WS 2006/07)
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Growth Rate and Sublimation Enthalpy
Dependence of vapour pressure on temperature: e.(High or ultra-high vacuum)
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
3
Organic Semiconductor Devices
Organic Field-Effect Transistors Plastic Electronics Organic Solar Cells Photovoltaics
Philips 2003
LIOS 2000
1.12.2005
Introduction to Materials Science Analysis Methods (WS 05/06) Prof. Dr. W. Brütting, EP IV, Uni Augsburg
Germanium Atomic weight Melting point (°C) Density (g/cm3) Atomic/Molecular density (cm-3) Crystal structure Lattice constant (Ǻ) Compressibility (cm2/dyn) Dielectric constant Energy gap (eV) Ionisation energy (eV) Electron mobility (cm2/Vs) Hole mobility (cm2/Vs) Thermal expansion coefficient (K-1) Specific heat (J/gK) Sound velocity (cm/s) 72.63 937 5.33 4.42 × 1022 Diamond 5.66 1.3 × 10-12 16 0.66 4.8 3800 1800 6.1 × 10-6 0.31 9.4 × 105 Anthracene 178.22 217 1.28 0.42 × 1022 Monoclinic 6.04 – 11.16 9 × 10-12 3.2 4.0 5.8 ~1 ~1 140 × 10-6 1.3 3.4 × 105 (All data measured at 300K.)