Organic devices for solid state lighting  [Elektronische Ressource] : technology and processing / vorgelegt von Philipp van Gemmern
124 pages
English

Découvre YouScribe en t'inscrivant gratuitement

Je m'inscris

Organic devices for solid state lighting [Elektronische Ressource] : technology and processing / vorgelegt von Philipp van Gemmern

Découvre YouScribe en t'inscrivant gratuitement

Je m'inscris
Obtenez un accès à la bibliothèque pour le consulter en ligne
En savoir plus
124 pages
English
Obtenez un accès à la bibliothèque pour le consulter en ligne
En savoir plus

Description

Organic Devices for Solid State Lighting-Technology and ProcessingVon der Fakultät für Elektrotechnik und Informationstechnik derRheinisch-Westfälischen Technischen Hochschule Aachen zur Erlangung desakademischen Grades eines Doktors der Ingenieurwissenschaften genehmigteDissertationvorgelegt vonDiplom-IngenieurPhilipp van Gemmernaus KrefeldBerichter: Prof. Dr.-Ing. M. HeukenProf.Dr.-Ing.R.H.JansenProf. Dr. rer. nat. M. WuttigTag der mündlichen Prüfung: 11.08.2008Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.Für Jessie.ContentsList of Organic Materials 6List of Abbreviations 7List of Figures 9List of Tables 121 Introduction and Motivation 132 OLED - Benefits, Applications and Requirements 162.1 BenefitsofOLED............................. 162.2 AplicationsandRequirements...................... 172.3 Conclusion................................. 193 Physical Fundamentals of Organic Semiconductors 203.1 ChargeTransportinOrganicMaterials.................. 203.1.1 Injection-limitedcurrents..................... 203.1.2 Transport-limitedcurents..................... 23.1.3 Field-Dependency of Charge Carrier Mobility . . . . . . . . . . . 243.2 EnergyTransferMechanismsinOrganicMaterials............ 253.3 ElectricalDopingofOrganicMaterials.................. 254 Principles and State of the Art of OLED 274.1 BasicPrincipleofOLED.......................... 274.2 EfficiencyofOLED............................ 294.

Informations

Publié par
Publié le 01 janvier 2008
Nombre de lectures 9
Langue English
Poids de l'ouvrage 4 Mo

Extrait

Organic Devices for Solid State Lighting
-
Technology and Processing
Von der Fakultät für Elektrotechnik und Informationstechnik der
Rheinisch-Westfälischen Technischen Hochschule Aachen zur Erlangung des
akademischen Grades eines Doktors der Ingenieurwissenschaften genehmigte
Dissertation
vorgelegt von
Diplom-Ingenieur
Philipp van Gemmern
aus Krefeld
Berichter: Prof. Dr.-Ing. M. Heuken
Prof.Dr.-Ing.R.H.Jansen
Prof. Dr. rer. nat. M. Wuttig
Tag der mündlichen Prüfung: 11.08.2008
Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.Für Jessie.Contents
List of Organic Materials 6
List of Abbreviations 7
List of Figures 9
List of Tables 12
1 Introduction and Motivation 13
2 OLED - Benefits, Applications and Requirements 16
2.1 BenefitsofOLED............................. 16
2.2 AplicationsandRequirements...................... 17
2.3 Conclusion................................. 19
3 Physical Fundamentals of Organic Semiconductors 20
3.1 ChargeTransportinOrganicMaterials.................. 20
3.1.1 Injection-limitedcurrents..................... 20
3.1.2 Transport-limitedcurents..................... 2
3.1.3 Field-Dependency of Charge Carrier Mobility . . . . . . . . . . . 24
3.2 EnergyTransferMechanismsinOrganicMaterials............ 25
3.3 ElectricalDopingofOrganicMaterials.................. 25
4 Principles and State of the Art of OLED 27
4.1 BasicPrincipleofOLED.......................... 27
4.2 EfficiencyofOLED............................ 29
4.3 State of the Art Performance of OLED and Research on OVPD . . . . . 30
5 The OVPD Technology 33
5.1 ThePrincipleofOVPD.......................... 3
5.2 TheCloseCoupledShowerheadTechnology ............... 35
5.3 Material Transport Regimes and Growth Mechanisms in OVPD . . . . . 36
5.3.1 MasTransportinaShowerheadSystem............. 36
5.3.2 Convection- and Diffusion-Limited Transport Regimes . . . . . . 38
5.4 OVPDProcesParameters........................ 38
5.4.1 Economical Impact of Process Parameters . . . . . . . . . . . . 39
3Contents
5.5 Organic Thin Films versus Conventional Semiconductors . . . . . . . . . 40
6 Experimental Setup 42
6.1 OVPDSystem............................... 42
6.2 VTESystem................................ 4
6.3 MeasurementMethods .......................... 45
7 Properties of Utilized Organic Materials and Evaluation of OVPD Process
Stability 47
7.1 Properties of Utilized Organic Materials . . . . . . . . . . . . . . . . . 47
7.2 Temperature Stability of Organic Sources and Homogeneity of Material
Deposition................................. 49
7.3 Run-to-Run and Day-to-Day Stability of Organic Single Layer Deposition 52
7.4 ImpactofFlowProfileonDepositionRates ............... 53
7.5 Run-to-Run Stability of OLED . . . . . . . . . . . . . . . . . . . . . . 56
7.6 Summary.................................. 57
8 Development of Long-Living Blue OLED with VTE for a Transfer to
OVPD 58
8.1 TheBH1:BE1Host/GuestSystem.................... 58
8.2 DescriptionofEmployedDeviceStructures................ 60
8.3 Discussion of Efficiencies and Lifetimes of Blue OLED . . . . . . . . . . 61
8.4 Summary.................................. 65
9 Development of Red, Green and Blue Monochrome OLED with OVPD 67
9.1 Influence of Coolant Temperature and Deposition Chamber Pressure on
OrganicSingleLayersandMonochromeBlueOLED........... 67
9.2 Influence of Coolant Temperature on Organic Single Layers and Phospho-
rescentRedOLED............................. 73
9.3 Phosphorescent Green OLED with Twofold Emission Layer . . . . . . . 77
9.3.1 DoE: Influence of the Experimental Factors on the Current Efficiency 78
9.3.2 DoE: Influence of the Experimental Factors on the Power Efficiency 82
9.3.3 Physical Interpretation of the DoE Results for Phosphorescent
GrenOLED............................ 84
9.4 Summary.................................. 89
10 Development of White OLED with OVPD 91
10.1 1:1 Transfer of a White Emitting Stack from VTE to OVPD . . . . . . 91
10.2Summary.................................. 9
11 p-Doping with OVPD for Improved Hole Injection and Transport 101
11.1 Organic Single Layers of p-Dopant and Single Layer Devices of Host and
p-Dopant.................................. 101
4Contents
1.2OLEDwithp-DopedHoleTransportLayer................ 104
1.3Summary.................................. 106
12 Implications for OVPD Technology Improvements 107
12.1 Reproducibility of Substrate Temperature . . . . . . . . . . . . . . . . . 107
12.2PreventionofRe-EvaporationofOrganicMaterials ........... 108
12.3TemporaryAdsorptionofOrganicMaterials ............... 108
13 Summary and Conclusion 110
Bibliography 113
List of Publications 119
Acknowledgements 122
Vitae 124
5Organic Materials
α-NPD: N,N’-diphenyl-N,N’-bis(1-naphthylphenyl)-1,1’-biphenyl-4,4’-diamine
Alq : tris-(8-hydroxyquinoline) aluminum
3
BAlq: aluminum(III)bis(2-methyl-8-quinolinato)4-phenylphenolate
BE1:N/A
BH1:N/A
BPhen: 4,7-diphenyl-1,10-phenanthroline
CBP: 4,4’-bis(carbazol-9-yl)-biphenyl
CuPc: copper phthalocyanine
F TCNQ: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane
4

2FIrpic: iridium(III)-bis[(4,6-difluorophenyl)pyridinato-N,C ]
HIM1:N/A
Ir(ppy) : tris-(phenyl-pyridyl)-Ir
3
PD1:N/A
PH1:N/A
PTCBI: 3,4,9,10-perylenetetracarboxylic bis-benzimidazole
RE1:N/A
TPBI: 1,3,5-tris-(N-phenylbenzimidazol-2-yl)benzene
TPD: N,N’-bis(3-methylphenyl)-N,N’-bis(phenyl)-benzidine
For some organic materials, the chemical denotation is given as ’N/A’. In this case,
the details were known to the author but cannot be published due to non-disclosure
agreements. These materials are abbreviated with names indicating their purpose. ’BE’
means blue emitter, ’BH’ blue host, ’HIM’ hole injection material, ’PD’ p-dopant, ’PH’
phosphorescent host, and ’RE’ red emitter.
6List of Abbreviations
AFM: atomic force microscopy
Al: aluminum
a.u.: arbitrary units
CCS: close coupled showerhead
CFD: computational fluid dynamic
CIE: Commission Internationale del’Eclairage
CoO:costofownership
CRI: color rendering index
CV: cyclic voltammetry
D.I.:de-ionized
DoE: design of experiments
DSC: differential scanning calorimetry
DtD:day-to-day
EL: electroluminescence
EML: emission layer
EQE: external quantum efficiency
ETL: electron transport layer
ETM: el transport material
HBL: hole blocking layer
HID: high-intensity discharge
HIL: hole injection layer
HPLC: high performance liquid chromatography
HOMO: highest occupied molecular orbital
HTL: hole transport layer
HTM: hole transport material
IP: ionization potential
ITO: indium tin oxide
I-V: current/voltage
I-V-L: current/voltage/luminance
LED: light emitting diode
LiF: lithium fluoride
LUMO: lowest unoccupied molecular orbital
MFC: mass flow controller
MoO : molybdenum oxidex
N : nitrogen
2
OLED: organic light emitting diode
OVPD: organic vapor phase deposition
PL: photoluminescence
RL: runline
rms: root mean square
7rpm: rounds per minute
RT: room temperature
RtR: run-to-run
SCLC: space charge limited conduction
SEE: secondary electron emission
Si: silicon
SSL: solid state lighting
TA: thermal analysis
TC: thermo couple
TCO: transparent conductive oxide
UPS: ultraviolet photoelectron spectroscopy
UV:ultraviolet
VBM: valence band maximum
VTE: vacuum thermal evaporation
8List of Figures
3.1 Tunneling through a triangular barrier Δ. .................... 21
3.2 Simulation results of a unipolar single layer device. (a) Variation of trap level, (b)
intrinsic charge carrier concentration, (c) trap density, (d) standard deviation [16]..24
3.3 Simplified illustration of the principle of electrical doping of organic semiconductors. 26
4.1 Schematic structure of a bottom-emitting OLED. ................ 27
4.2 Principle device structures for the generation of white light. A combination of three
emissive materials (red, green, blue) which can either be vertically stacked (left) or
laterally arranged (center). Blue OLED with down-conversion phosphor (right).... 28
5.1 Vapor pressure versus evaporation temperature for materials with different ΔH (a>b>c)
S
(left). Theoretical deposition rate versus carrier gas flow in a gas phase deposition pro-
cess for different vapor pressures (a>b>c) (right). [52].............. 34
5.2 Showerhead model for the simulation of the gas flow pattern (top). Simulated velocity
distribution in the vapor phase in a showerhead system (bottom). Figures courtesy of
AIXTRON AG. ............................... 37
5.3 Cost of ownership in units of $ per mother glass (MG) and cycle time versus the total
flow [59]. .................................. 40
6.1 Standard substrate layout for OLED fabrication in the OVPD system. ....... 43
6.2 Example of a 6" Si wafer with seven out of eight segments coated with organic materials. 44
7.1 Comparison of ionization energies obtained by UPS and CV. ........... 50
7.2 Temperature stability of an OVPD source container for organic material over a period
of four weeks. ................................ 50
7.3 Homogeneity of or

  • Univers Univers
  • Ebooks Ebooks
  • Livres audio Livres audio
  • Presse Presse
  • Podcasts Podcasts
  • BD BD
  • Documents Documents