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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Defects play a key role in the physical properties of semiconductors and devices, and their identification is essential in assessing the reliability of electronic devices. Defects in Organic Semiconductors and Devices introduces the fundamental aspects of defects in organic semiconductors and devices in relation to the structure of materials and architecture of electronic components. It covers the topics of defect formation and evolution, defect measurement techniques and their adaption to organic devices, the effects of defects on the physical properties of materials and their effects on the performance and lifetime of organic devices. Identifying defects and determining their characteristics in the structure of organic devices such as OLEDs, OFETs and OPVs make it possible to better understand degradation processes and develop solutions to improve the reliability of such devices. This book is intended for researchers and students in university programs or engineering schools who are specializing in electronics, energy and materials.
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Veröffentlichungsjahr: 2023
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Table of Contents
Cover
Table of Contents
Title Page
Copyright Page
Abbreviations
General abbreviations
Chemical materials
Introduction
1 Overview of Organic Semiconductors
1.1. Organic semiconductors
1.2. Doping of organic semiconductors
1.3. Organic electronic devices
2 Defects in Materials
2.1. Order and disorder
2.2. Crystalline semiconductors
2.3. Amorphous semiconductors
2.4. Organic semiconductors
2.5. Distribution of the energetic states
3 Defects and Physical Properties of Semiconductors
3.1. Carrier transport in organic semiconductors
3.2. Effects of defects on the carrier transport
3.3. Optical properties of semiconductors and defects
4 Techniques for Studying Defects in Semiconductors
4.1. Electron spin resonance (ESR)
4.2. Optical techniques
4.3. Electrical techniques
5 Defect Origins
5.1. Defects in organic semiconductors
5.2. Defects in organic devices
6 Defects, Performance and Reliability of Organic Devices
6.1. Impact of defects on the performance of organic devices
6.2. Impact of defects on the stability of organic devices
Future Prospects
References
Index
Other titles frominElectronics Engineering
End User License Agreement
List of Illustrations
Chapter 1
Figure 1.1.
Delocalization of π-electrons in a single carbon ring benzene mole
...
Figure 1.2.
Schematic representation of characteristic energy levels in (a) in
...
Figure 1.3.
Schematic doping process in organic semiconductor in: a) N-type do
...
Figure 1.4.
(a) Basic architecture of organic diodes (OLEDs, OPVs) and (b) bil
...
Figure 1.5.
OFET device structures: (a) top gate-bottom contact (TG-BC), (b) t
...
Figure 1.6.
Typical structure of OLEDs with HTL and ETL transport layers and t
...
Figure 1.7.
Schematic structure of a multilayer OLED with injection, blocking
...
Figure 1.8.
(a) Schematic structure of the BHJ solar cell and (b) photovoltaic
...
Figure 1.9.
Schematic representation of emission mechanisms in organic emitter
...
Figure 1.10.
(a) Schematic representation of the operating mode of OFETs. (b)
...
Figure 1.11.
Schematic representation of the structure of a vertical organic f
...
Chapter 2
Figure 2.1.
Schematic representation of the energy band diagram of crystalli
...
Figure 2.2.
Schematic representation defects in crystalline semiconductors:
...
Figure 2.3.
Schematic representation of the density of states (DOS) in (a) a
...
Figure 2.4.
Schematic representation of the polymer network elements
Figure 2.5.
Schematic representation of the DOS of organic semiconductors.
Figure 2.6.
Schematic representation of the distribution types of energetic
...
Chapter 3
Figure 3.1.
Schematic representation of the formation of an electron polaron
...
Figure 3.2.
Schematic equilibrium energy distribution of carriers in a Gauss
...
Figure 3.3.
Charge carrier transitions in semiconductors: (a) generation (ex
...
Figure 3.4.
Potential energy of: (a) an attractive trapping center, (b) a ne
...
Figure 3.5.
...
Figure 3.6.
Absorption edge of semiconductors with direct allowed transition
...
Figure 3.7.
Absorption transitions between trapping centers and the conducti
...
Figure 3.8.
Luminescence transitions between trapping centers and the allowe
...
Figure 3.9.
Time dependence of the luminescence intensity under an applied l
...
Chapter 4
Figure 4.1.
ESR absorption spectrum and its first derivative
Figure 4.2.
Comparison between EPR spectra of undoped CdSe QDs measured at roo
...
Figure 4.3.
Steady-state PL spectra in P3HT: (a) Schematic representation of 0
...
Figure 4.4.
Principle of the TSL measurement.
Figure 4.5.
TSL process: 1 – creation of excitons during irradiation; 2 and 3
...
Figure 4.6.
Comparison of TSL spectra of first and second order (with and with
...
Figure 4.7.
Experimental parameters at different stages of the TSL spectroscop
...
Figure 4.8.
Tm − Tstop technique: heating cycle scheme of the sample: 1 – prer
...
Figure 4.9.
Tm – Tstop plot: (a) single discrete trap TSL spectrum, (b) stairc
...
Figure 4.10.
Tm – Tstop glow curves recorded aluminosilicate glass from 293 K
...
Figure 4.11.
Schematic representation of the principle of the TSC technique.
Figure 4.12.
Illustration example of the fitting steps of a TSC spectrum: (1)
...
Figure 4.13.
(a) Fractional TSC spectra in a ITO/PEDOT/PF-N-Ph/Al diode in the
...
Figure 4.14.
Schematic plot of J–V characteristics showing conduction regimes
...
Figure 4.15.
Schematic representation of the energy band diagram of a semicond
...
Figure 4.16.
Schematic plots of: (a) the SCLC current-voltage characteristics
...
Figure 4.17.
Schematic representation of the capacitance related to the depl
...
Figure 4.18.
...
Figure 4.19.
Drive-level capacitance profiling showing the variation of junc
...
Figure 4.20.
Basic equivalent circuits and their capacitance function as a f
...
Figure 4.21.
The Nyquist plots of the basic equivalent circuits: (a) RC para
...
Figure 4.22.
Nyquist plot for: (a) a perfect device with negligible contact
...
Figure 4.23.
Schematic representation of the capacitance and its differentia
...
Figure 4.24.
Capacitance (left) and differential capacitance (right) of an I
...
Figure 4.25.
The defect energy distribution of CH3NH3Pbh perovskite (from Du
...
Figure 4.26.
Equivalent circuits of devices containing high trap densities:
...
Figure 4.27.
Variation of the space charge region with an applied voltage pu
...
Figure 4.28.
Schematic representation of the occupancy of trap states in the
...
Figure 4.29.
Transient capacitance C(t) of an ITO/PPV/Al structure (from Cam
...
Figure 4.30.
DLTS spectra for two samples: #1 and #2 of CIGS of efficiencies
...
Figure 4.31.
Schematic representation of a measured DLTS spectrum and its co
...
Figure 4.32.
Schematic diagram of a measured Q-DLTS spectrum: (a) timing dia
...
Figure 4.33.
Q-DLTS spectra obtained from an ITO/MEH-PPV/Al device using a c
...
Figure 4.34.
Schematic representation of the effect of charging time to fill
...
Figure 4.35.
Q-DLTS spectra recorded in an ITO/PEDOT/(PVK+PBD)/Al diode at 3
...
Figure 4.36.
Schematic measurement principle of the time-of-flight experimen
...
Figure 4.37.
Photocurrent transient: (a) in non-dispersive transport, (b) in
...
Figure 4.38.
CELIV characteristics of the applied voltage ramp and the curre
...
Chapter 5
Figure 5.1.
Resolved Q-DLTS spectra of ITO/(PF-N-Ph)/Ca/Al and ITO/PEDOT:PSS
...
Figure 5.2.
XPS profiles of aluminum, carbon, nitrogen, oxygen and indium in
...
Chapter 6
Figure 6.1.
a) Physical processes of light emission in basic OLED structure:
...
Figure 6.2.
(a) Working principle of organic solar cells. (b) Geminate and n
...
Figure 6.3.
a) Schematic OFET structure. b) Schematic transfer characteristi
...
Figure 6.4.
Representative decay curve of the device parameter for defining
...
Figure 6.5.
Schematic evolution with time of the OLED luminance and applied
...
Figure 6.6.
Q-DLTS spectra of a fresh and an aged ITO/PEDOT:PSS/PF/Ca/Al dio
...
Figure 6.7.
Principle of thermally activated delayed fluorescence.
Figure 6.8.
Q-DLTS spectra of a fresh and an aged ITO/PEDOT/P3HT:PCBM/Ca/Al
...
Figure 6.9.
Threshold voltage variations for pentacene OFETs during bias str
...
Figure 6.10.
Evolution of the ΔVTH under different stress conditions. (Wrach
...
Guide
Cover Page
Title Page
Copyright Page
Abbreviations
Introduction
Table of Contents
Begin Reading
Future Prospects
References
Index
Other titles from in Electronics Engineering
WILEY END USER LICENSE AGREEMENT
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Defects in Organic Semiconductors and Devices
Thien-Phap Nguyen
First published 2023 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd27-37 St George's RoadLondon SW19 4EUUK
John Wiley & Sons, Inc.111 River StreetHoboken, NJ 07030USA
www.iste.co.uk
www.wiley.com
© ISTE Ltd 2023The rights of Thien-Phap Nguyen to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s), contributor(s) or editor(s) and do not necessarily reflect the views of ISTE Group.
Library of Congress Control Number: 2023937986
British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISBN 978-1-78630-926-6
Abbreviations
General abbreviations
AFM
Atomic Force Microscopy
BHJ
Bulk Heterojunction
CELIV
Charge Carrier Extraction by Linearly Increasing Voltage
CPE
Constant Phase Element
CTC
Charge Transfer Complex
DLCP
Drive-Level Capacitance Profiling
DLOS
Deep-Level Optical Spectroscopy
DLTS
Deep-Level Transient Spectroscopy
DOS
Density of States
EA
Electron Affinity
EBL
Electron Blocking Layer
EDX
Energy-Dispersive X-Ray Spectroscopy
EIL
Electron Injection Layer
EML
Emitting Layer
ENDOR
Electron Nuclear Double Resonance
EQE
External Quantum Efficiency
ESR-EPR
Electron Spin Resonance-Electron Paramagnetic Resonance
ETL
Electron Transport Layer
FL
Fluorescence
FLIM
Fluorescence Lifetime Imaging Microscopy
GDM
Gaussian Disorder Model
HBL
Hole-Blocking Layer
HIL
Hole Injection Layer
HOMO
Highest Occupied Molecular Orbital
HTL
Hole Transport Layer
IE
Ionization Energy
IQE
Internal Quantum Efficiency
IS
Impedance Spectroscopy
ITC
Ionic Thermo-Current
KPFM
Kelvin Probe Force Microscopy
LESR
Light-Induced Electron Spin Resonance
LUMO
Lowest Unoccupied Molecular Orbital
NFA
Non-Fullerene Acceptors
NREL
National Renewable Energy Laboratory
OFET
Organic Field-Effect Transistor
OLED
Organic Light-Emitting Diode
OLET
Organic Light-Emitting Transistor
OPV-OSC
Organic Photovoltaic-Organic Solar Cell
OTR
Oxygen Transmission Rate
PCE
Power Conversion Efficiency
PDS
Photothermal Deflection Spectroscopy
PL
Photoluminescence
PLQY
Photoluminescence Quantum Yield
QD
Quantum Dot
RISC
Reverse Intersystem Crossing
SCLC
Space Charge-Limited Current
SQUID
Superconducting Quantum Interference Device
SSPL
Steady-State Photoluminescence
STM
Scanning Tunneling Microscopy
TADF
Thermally Activated Delayed Fluorescence
TAS
Transient Absorption Spectroscopy
TEM
Transmission Electron Microscopy
TOF
Time of Flight
TOF-SIMS
Time-of-Flight Secondary Ion Mass Spectroscopy
TRPL
Time-Resolved Photoluminescence
TSC
Thermally Stimulated Current
TSL
Thermally Stimulated Luminescence
TSPC
Thermally Stimulated Polarization Current
UPS
Ultraviolet Photoemission Spectroscopy
VOFET
Vertical Organic Field-Effect Transistor
WAXS
Wide-Angle X-Ray Scattering
WOLED
White Organic Light-Emitting Diode
WVTR
Water Vapor Transmission Rate
XPS
X-Ray Photoemission Spectroscopy
Chemical materials
1-NaphDATA
4,4′,4″-tris(N-2-naphthyl)-N-phenylamino-triphenylamine
4T
α
-quaterthiophene
6T
α
-sexithiophene
Alq3
tris(8-hydroxyquinolinato) aluminum
BCF
tris(penta fluorophenyl) borane
BDT
benzodithiophene
Bphen
4,7-diphenyl-1,10-phenanthroline
BT-CIC
(4,4,10,10-tetrakis(4-hexylphenyl)-5,11-(2-ethylhexyloxy)-4,10-dihydrodithienyl[1,2-
b
:4,5
b
’] benzodithiophene-2,8-diyl)bis(2-(3-oxo-2,3-dihydroinden-5,6-dichloro-1-ylidene)malononitrile)
BTA3
benzotriazole
BTP-eC9-2Cl
2,2′[[12,13-bis(2-butyloctyl)-12,13-dihydro-3,9-dinonylbisthieno [2″,3″:4′,5] pyrrolo[3,2-e:2′,3′-g][1–3] benzothiadiazole-2,10-diyl]bis[methylidyne(5,6-chloro-3-oxo-1H-indene-2,1(3H)-diylidene)]] bis[propanedinitrile]
CBP
4,4′-bis(N-carbazolyl)-1,1′-biphenyl
CdSe
cadmium selenide
CH
3
NH
3
PbBr
3
methylammonium lead tribromide
CH
3
NH
3
PbI
3
(MAPI)
methylammonium lead triiodide
CuOx
copper oxide
CuPc
copper phthalocyanine
CuSCN
copper(I) thiocyanate
DH4T
dihexyl-quaterthiophene
F4-TCNQ
tetrafluoro tetracyanoquinodimethane
FAPbI
3
formamidine lead triiodide
FIrpic
iridium(III)bis(4,6-(difluorophenyl)pyridinato-N,C2′)picolinate
HATCN
hexa-azatri-phenylene-hexanitrile
HMDS
hexamethyl-disilazane
IDTBR
(5Z,5′Z)-5,5′-((7,7′-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl) bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene)) bis(3-ethyl-2-thioxothiazolidin-4-one)
Ir(ppy)3
fac-tris-(2-phenylpyridine)iridium(III)
ITIC (C
94
H
82
N
4
O
2
S
4
)
3,9-bis(2-methylene-(3 -(1,1 -dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′] dithiophene
LiF
lithium fluoride
MDMO-PPV
poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-p-phenylene vinylene]
MEH-PPV
poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene]
MeLPPP
methyl-substituted ladder-type poly para-phenylene
MeO-TPD
N,N′-diphenyl-N,N′-bis(3-methyl-phenyl)-[1,1′-biphenyl]-4,4′-diamine
MoO
3
molybdenum(VI) oxide
NPB
N,N′-diphenyl-N,N′-bis(1 -naphthyl)-1,1′-biphenyl-4,4′-diamine
NPD
N,N′-di( 1-naphthyl)-N,N′-diphenylbenzidin
NRS-PPV
poly[{2-[4-(3′,7′-dimethyloctyloxyphenyl)]}-co-{2-methoxy-5-(3′,7′-dimethyl octyloxy)}-1,4-phenylene vinylene]
OC
1
C
10
-PPV
poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-p-phenylene vinylene]
OC
8
C
8
poly[p-(2,5-di(2-ethylhexyloxy)phenylenevinylene]
P3DDT
poly(3-dodecyl thiophene-2,5-diyl)
P3MeT
poly(3-methylthiophene)
PBD
2-(4-biphenylyl)-5-(4-tert-butyl-phenyl)-(1,3,4-oxadiazole)
PBDB-TF
poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’- bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’] dithiophene-4,8-dione))]
PBQx
benzodithiophene-dithieno[3,2-f:2′,3-h] quinoxaline pentacene
Pc
pentacene
PCBM
[6,6]-phenyl-C61-butyric acid methyl ester
PCDA
10,12-pentacosadiynoic acid
PCDTBT
poly[N-9’-heptadecanyl-2,7-carbazol-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazol)]
PCNEPV
poly[oxa-1,4-phenylene-(1-cyano-1,2-vinylene)-(2-methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylene)-1,2-(2-cyanovinylene)-1,4-phenylene]
PDI
perylene diimide
PEDOT:PSS
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate
PET
polyethylene-terephthalate
PF-N-Ph
poly(9,9-dihexylfluorene-co-N,N-di(9,9-dihexyl-2-fluorenyl)-N-phenylamine)
PMPSi
polymethyl-phenylsilylene
PPP
poly(p-phenylene)
PPQ
phenyl-quinoxaline
PPV
poly(p-phenylene-vinylene)
PRA
1-phenyl-3 -(p-diethylaminostyryl)-5-(p-diethylaminophenyl) pyrazoline
PTAA
poly(triarylamine)
PTB7
poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl]]
PTCBI
3,4,9,10-perylenetetracarboxylic-bis-benzimidazole
PVK
poly(9-vinylcarbazole)
rrP3DDT
regio-regular poly(3-dodecyl thiophene-2,5-diyl)
Spiro-OMeTAD
(2,2′,7,7′-tetrakis(N,N-di-p-methoxy phenylamine)-9,9′-spirobifluorene)
SubPc
subphthalocyanine-chloride
TPD
N,N′-diphenyl-N,N′-bis(3-methylphenyl)(1,1′-biphenyl)-4,4′-diamin
TPQ
trisphenyl-quinoxaline
Y6 (BTB-4F)
2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13dihydro[1,2,5]thiadiazolo[3,4e]thieno[2″,3″:4′,5′]thi eno [2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1 diylidene))dimalononitrile
ZnPc
zinc phthalocyanine
Introduction
In a movie that was directed by Billy Wilder, one character declared “Well... nobody's perfect!” in order to excuse his partner's shortcomings, that is, in this situation, his way of life, which was substantially different from what he had portrayed. This statement may seem obvious, although no one can claim that they know everyone around them completely. On the other hand, in the field of materials and devices, it is well known that nothing is perfect due to the presence of defects within their structures and architectures. For instance, the density of defects in conventional semiconductors, such as silicon, is estimated to be higher than 1011 cm-3 at room temperature for intrinsic samples. As defects affect the quality and the properties of materials, and, consequently, the performance of devices using them, it is essential to control their density in order to ensure their reliability. Indeed, when we create, produce or acquire a material or device, we would like to have the best performance and the longest lifetime from its use. This requires careful control of not only the production process but also the characteristics of the materials used. In electronic devices, the physical properties of semiconductors are strongly dependent on the defect states, and it is essential to identify and understand their formations, their locations and to determine their densities in order to obtain reproducible materials with known and controlled defect parameters and to establish their reliability.
Conventional semiconductors such as silicon and germanium are crystalline solids, where the atoms form a periodic arrangement. This ordered structure provides highly interesting electrical and optical properties to the semiconductors that are used to build electronic components and devices. Since the invention of transistors, myriad applications have been achieved in the field of electronics, bringing great comfort to everyday life: TVs, lighting, computers and cell phones, to name but a few. However, as stated by Victor Hugo, “On voit les qualités de loin et les défauts de près” (we see qualities at a distance and defects at close range), despite their remarkable and numerous qualities, it was very quickly observed that many of the first electronic devices manufactured using conventional semiconductors malfunctioned, despite careful control of the processing. Through investigations of the defective parts, it was found and later proved that, irrespective of the particular devices, the nature of the materials played a primary role in the reliability of the electronic products, whose yield is closely linked to the presence of defects.
As perfect materials do not exist, the properties of conventional semiconductors are affected by defects which interrupt the crystalline pattern. Common types of defects include point defects (impurities, interstitials, vacancies, etc.), dislocations, and grain boundaries can be formed during the processing but can also be intentionally (doping) or unintentionally (contamination, degradation) incorporated in the prepared materials. In the doping process, impurities are intentionally introduced to materials in order to modify and control the conduction of the semiconductors by adding energy states in a band gap, which provide charge carriers to the conduction or valence bands. These defects have a beneficial effect on the electrical properties of the materials. In most other cases, defects have negative or detrimental effects on the properties and functionalities of materials by enhancing the disorder, impeding the charge transport and affecting the overall physical processes in the semiconductors. As defects are unavoidable, it is necessary to acquire accurate knowledge of their origin and their effects in order to efficiently control and eventually eliminate them. Investigations of defects in conventional semiconductors have been intensively developed with well-established and elaborated measurement techniques in order to determine the defect parameters in materials and devices, improving the knowledge of their origin and their effects on the performance of the devices studied. At the same time, diverse physical models on the material structure, energetic distribution and charge carrier kinetics have been proposed and successfully applied in order to elucidate defect measurement results in most conventional semiconductors.
Structurally speaking, organic semiconductors differ from conventional semiconductors. Since there is no defined orientation and order of molecules that make up the organic matter, they can be classified as amorphous materials. The lack of orientational order combined with the weak van der Waals bonding forces make the organic materials likely to form defects, which can be explained by the small amount of energy needed to displace the molecule from its equilibrium position. Indeed, similarly to inorganic semiconductors, impurities and structural defects such as point defects, dislocations and grain boundaries can be formed or introduced to the organic semiconductors during the synthesis and the processing of materials. Due to their nature and chemical structure, they are also more sensitive than their inorganic counterparts to contact with environmental media. The structural changes due to the interactions between the organic material and the environment often lead to the formation of defects in the contact region. From this consideration, we can expect defects in organic materials to be investigated by applying similar methodology and techniques as in conventional semiconductors. To take the specific properties of the organic materials into account, further advanced measurement techniques and methodology approaches need to be used and developed, and the results obtained must be effectively analyzed and used.
This book aims to provide a comprehensive introduction on the defects and degradation of semiconductors used in electronic organic devices. It is organized as follows:
The first chapter is an overview of organic semiconductors and devices, in which fundamental notions of the materials and the main applications in organic electronics are presented.
Chapter 2 reviews the concept of defects in inorganic and organic semiconductors in relation to the notion of order/disorder, the density of states (DOS) and the localized states in the band gap.
In Chapter 3, the effects of defects on the electrical and optical properties of the organic materials are described. These properties are of primary importance for the operation of organic devices such as OLEDs and OPVs and also for defect measurement techniques.
Chapter 4 presents the main measurement techniques for determining the defect parameters in both organic and conventional semiconductors, which include paramagnetic resonance, optical and electrical techniques. The principle of the methods is described, the analysis of the results to extract the defect parameters (whenever possible) is explained and for applications, selected typical examples of defect measurement in organic devices from the literature are given.
Chapter 5 reports the results obtained from the defect measurements in different organic semiconductors and devices. Defects from the active layer, the transport layers, from the surface, and interface and surface, and from diffused impurities are detected in the organic devices studied.
Chapter 6 presents the correlation between defects and reliability in organic devices by studying the influence defects have on the efficiency, the lifetime and the degradation processes of devices such as OLEDs, OPVs and OFETs.
I would like to thank ISTE Ltd for publishing this book, and I hope that it will help readers to better understand some aspects of defects in organic semiconductors and devices.
