Organic Semiconductors for Optoelectronics (Wiley Series in Materials for Electronic & Optoelectronic Applications)

Cover
Title Page
Copyright
Contents
List of Contributors
Series Preface
Preface
Chapter 1 Electronic Structures of Organic Semiconductors
	1.1 Introduction
	1.2 Electronic Structures of Organic Crystalline Materials
		1.2.1 Free‐Electron Picture
		1.2.2 Tight‐Binding Framework
			1.2.2.1 Formalism
			1.2.2.2 Simple Example
		1.2.3 Electronic Properties Based on the Electronic Structure
			1.2.3.1 Characteristics of the Energy Band
			1.2.3.2 Band Gap (ΔEg)
			1.2.3.3 Fermi Energy (εF) and Fermi Level (EF)
			1.2.3.4 Band Width (W)
			1.2.3.5 Ionization Potential (Ip)
			1.2.3.6 Electron Affinity (Ea)
			1.2.3.7 Density of States (DOS)
			1.2.3.8 Effective Mass (m*)
			1.2.3.9 CO Pattern
			1.2.3.10 Electron Density and Bond Order
			1.2.3.11 Total Energy of 1D Crystal (Etot)
			1.2.3.12 Mobility
	1.3 Injection of Charge Carriers
		1.3.1 Organic Conductive Polymers
		1.3.2 Organic Charge‐Transfer Crystals
	1.4 Transition from the Conductive State
		1.4.1 Peierls Transition
			1.4.1.1 Polyacetylene
			1.4.1.2 TTF‐TCNQ
		1.4.2 Competition of Spin Density Wave and Superconductivity
	1.5 Electronic Structure of Organic Amorphous Solid
		1.5.1 Examination of Electronic Structures
			1.5.1.1 Direct Calculation of the Local Structure
			1.5.1.2 Effective‐Medium Approximation
		1.5.2 Localized Levels and Mobility Edge
		1.5.3 Hopping Process
			1.5.3.1 Hopping Process between the Nearest Neighbors
			1.5.3.2 Variable Range Hopping (VRH)
			1.5.3.3 Hopping Process via the Dopants
	1.6 Conclusion
	Acknowledgment
	References
Chapter 2 Electronic Transport in Organic Semiconductors
	2.1 Introduction
	2.2 Amorphous Organic Semiconductors
		2.2.1 Measurements of Transport Properties
			2.2.1.1 Time‐of‐Flight Transient Photocurrent Experiment
	2.3 Experimental Features of Electronic Transport Properties
	2.4 Charge Carrier Transport Models
		2.4.1 Multiple Trapping Model
		2.4.2 Gaussian Disorder Model (GDM)
		2.4.3 Correlated Disorder Model (CDM)
		2.4.4 GDM vs. CDM
		2.4.5 Polaronic Transport
		2.4.6 Transport Energy
		2.4.7 Analytical Approach to Hopping Transport
		2.4.8 Functional Forms of Localized State Distributions
	2.5 Prediction of Transport Properties in Amorphous Organic Semiconductors
	2.6 Polycrystalline Organic Semiconductors
		2.6.1 Transport in Polycrystalline Semiconductors and Technological Importance of Polycrystalline Silicon
		2.6.2 Field‐Effect Mobility in Organic Polycrystalline Semiconductors
		2.6.3 Performance of Field‐Effect Transistors with Polycrystalline Organic Semiconductors
	2.7 Single‐Crystalline Organic Semiconductors
		2.7.1 Band Conduction in Single‐Crystalline Organic Semiconductors
		2.7.2 Performance of Field‐Effect Transistors with Single Crystalline Organic Semiconductors
	2.8 Concluding Remarks
	Acknowledgment
	References
Chapter 3 Theory of Optical Properties of Organic Semiconductors
	3.1 Introduction
	3.2 Photoexcitation and Formation of Excitons
		3.2.1 Photoexcitation of Singlet Excitons due to Exciton‐photon Interaction
		3.2.2 Excitation of Triplet Excitons
			3.2.2.1 Direct Excitation to Triplet States Through Exciton‐Spin‐Orbit‐Photon Interaction
			3.2.2.2 Indirect Excitation of Triplet Excitons Through Intersystem Crossing and Exciton‐Spin‐Orbit‐Phonon Interaction
	3.3 Exciton up Conversion
	3.4 Exciton Dissociation
		3.4.1 Process of Conversion from Frenkel to CT Excitons
		3.4.2 Dissociation of CT Excitons
	References
Chapter 4 Light Absorption and Emission Properties of Organic Semiconductors
	4.1 Introduction
	4.2 Electronic States in Organic Semiconductors
		4.2.1 Fluorescence Emitters
		4.2.2 Phosphorescence Emitters
		4.2.3 TADF Emitters
		4.2.4 &rmpi; Conjugated Polymers
	4.3 Determination of Excited‐state Structure Using Nonlinear Spectroscopy
		4.3.1 Background
		4.3.2 Experimental Technique
			4.3.2.1 EA
			4.3.2.2 TPE
		4.3.3 Experimental Results
			4.3.3.1 DE2
			4.3.3.2 Ir(ppy)3
			4.3.3.3 PFO
	4.4 Decay Mechanism of Excited States
		4.4.1 Background
		4.4.2 Experimental Technique
			4.4.2.1 Time‐resolved PL Measurements
			4.4.2.2 PLQE Measurements
		4.4.3 Experimental Results
			4.4.3.1 PFO
			4.4.3.2 Ir(ppy)3
			4.4.3.3 4CzIPN
	4.5 Summary
	Acknowledgement
	References
Chapter 5 Characterization of Transport Properties of Organic Semiconductors Using Impedance Spectroscopy
	5.1 Introduction
	5.2 Charge‐Carrier Mobility
		5.2.1 Methods for Mobility Measurements
		5.2.2 Theoretical Basis for Determination of Charge‐Carrier Mobility
		5.2.3 Determination of Charge‐Carrier Mobility
		5.2.4 Influence of Barrier Height for Carrier Injection on Determination of Charge‐Carrier Mobility
		5.2.5 Influence of Contact Resistance on Determination of Charge‐Carrier Mobility
		5.2.6 Influence of Localized States on Determination of Charge‐Carrier Mobility
		5.2.7 Demonstration of Determination of Charge‐Carrier Mobility
	5.3 Localized‐State Distributions
		5.3.1 Methods for Localized‐State Measurements
		5.3.2 Theoretical Basis for Determination of Localized‐State Distribution
		5.3.3 Demonstration of Determination of Localized‐State Distribution
	5.4 Lifetime
		5.4.1 Methods for Deep‐Trapping‐Lifetime Measurements
		5.4.2 Determination of Deep‐Trapping‐Lifetime using the Proposed Method
		5.4.3 Validity of the Proposed Method
		5.4.4 Demonstration of Determination of Deep‐Trapping‐Lifetime
	5.5 IS in OLEDs and OPVs
	5.6 Conclusions
	Acknowledgments
	References
Chapter 6 Time‐of‐Flight Method for Determining the Drift Mobility in Organic Semiconductors
	6.1 Introduction
	6.2 Principle of the TOF Method
		6.2.1 Carrier Mobility and Transient Photocurrent
		6.2.2 Standard Setup of the TOF Measurement
		6.2.3 Sample Preparation
		6.2.4 Current Mode and Charge Mode
		6.2.5 Instructions in the TOF Measurements
	6.3 Information Obtained From the TOF Experiments
	6.4 Techniques Related to the TOF Measurement
		6.4.1 Xerographic TOF Method
		6.4.2 Lateral TOF Method
		6.4.3 TOF Measurements Under Pulse Voltage Application
		6.4.4 Dark Injection Space Charge‐Limited Transient Current Method
	6.5 Conclusion
	References
Chapter 7 Microwave and Terahertz Spectroscopy
	7.1 Introduction
	7.2 Instrumental Setup of Time‐Resolved Gigahertz and Terahertz Spectroscopies
	7.3 Theory of Complex Microwave Conductivity in a Resonant Cavity
	7.4 Microwave Spectroscopy for Organic Solar Cells
	7.5 Frequency‐Modulation: Interplay of Free and Shallowly‐Trapped Electrons
	7.6 Organic‐Inorganic Perovskite
	7.7 Conclusions
	Acknowledgement
	References
Chapter 8 Intrinsic and Extrinsic Transport in Crystalline Organic Semiconductors: Electron‐Spin‐Resonance Study for Characterization of Localized States
	8.1 Intrinsic and Extrinsic Transport in Crystalline Organic Semiconductors
	8.2 Electron Spin Resonance Study for Characterization of Localized States
		8.2.1 Introduction into ESR Study
		8.2.2 ESR Spectra of Trapped Carriers
			8.2.2.1 ESR Spectra for Single Molecule and a Cluster Containing Several Molecules
			8.2.2.2 ESR Spectra for a Trap in Crystal
			8.2.2.3 ESR Spectra for Several Kinds of Traps
		8.2.3 From ESR Spectrum to Trap Distribution Over Degree of Localization
			8.2.3.1 Method to Solve Inverse Problem
			8.2.3.2 Tests of SOM Stability Against the Noise in Experimental Data
			8.2.3.3 Practical Implementation of Method: Distribution of Traps in Pentacene TFT
			8.2.3.4 Reliability of Trap Distribution Result
		8.2.4 Transformation From Spatial Distribution to Energy Distribution
			8.2.4.1 Trap Model: 2D Holstein Polaron and On‐Site Attractive Center
			8.2.4.2 Energy Distribution of Traps in Pentacene TFTs
		8.2.5 Discussion
		8.2.6 Summary of Trap Study
	8.3 Conclusion
	Acknowledgments
	References
Chapter 9 Second Harmonic Generation Spectroscopy
	9.1 Introduction
	9.2 Basics of the EFISHG
		9.2.1 Macroscopic Origin of the SHG
		9.2.2 Microscopic Description of the SHG
		9.2.3 EFISHG Measurements
		9.2.4 Evaluation of In‐plane Electric Field in OFET
		9.2.5 Direct Imaging of Carrier Motion in OFET
	9.3 Some Application of the TRM‐SHG to the OFET
		9.3.1 Trap Effect
		9.3.2 Metal Electrode Dependence
		9.3.3 Anisotropic Carrier Transport
	9.4 Application of the TRM‐SHG to OLED
	9.5 Conclusions
	Acknowledgement
	References
Chapter 10 Device Physics of Organic Field‐effect Transistors
	10.1 Organic Field‐Effect Transistors (OFETs)
		10.1.1 Structure of OFETs
		10.1.2 Operation Principles of OFETs
		10.1.3 Carrier Traps
		10.1.4 Transport Models in Channels
			10.1.4.1 Band Transport Model
			10.1.4.2 Multiple Trap and Release Model
			10.1.4.3 Hopping Model
			10.1.4.4 Dynamic Disorder Model
			10.1.4.5 Grain Boundary Model
		10.1.5 Carrier Injection at Source and Drain Electrodes
			10.1.5.1 Transmission Line Method (TLM)
			10.1.5.2 Four‐Terminal Measurement
			10.1.5.3 Effect of Contact Resistance on Apparent Mobility
	References
Chapter 11 Spontaneous Orientation Polarization in Organic Light‐Emitting Diodes and its Influence on Charge Injection, Accumulation, and Degradation Properties
	11.1 Introduction
	11.2 Interface Charge Model
	11.3 Interface Charge in Bilayer Devices
	11.4 Charge Injection Property
	11.5 Degradation Property
	11.6 Conclusions
	Acknowledgement
	References
Chapter 12 Advanced Molecular Design for Organic Light Emitting Diode Emitters Based on Horizontal Molecular Orientation and Thermally Activated Delayed Fluorescence
	12.1 Introduction
	12.2 Molecular Orientation in TADF OLEDs
	12.3 Molecular Orientation in Solution Processed OLEDs
	References
Chapter 13 Organic Field Effect Transistors Integrated Circuits
	13.1 Introduction
	13.2 Organic Fundamental Circuits
		13.2.1 Inverter for Logic Components
		13.2.2 Logic NAND and NOR Gates
		13.2.3 Active Matrix Elements
	13.3 High Performance Organic Transistors Applicable to Flexible Logic Circuits
		13.3.1 Reducing the Contact Resistance
		13.3.2 Downscaling the Channel Sizes and Vertical Transistors
		13.3.3 High‐Speed Organic Transistors
	13.4 Integrated Organic Circuits
		13.4.1 RFID Tag Applications
		13.4.2 Sensor Readout Circuits
	13.5 Conclusions
	References
Chapter 14 Naphthobisthiadiazole‐Based Semiconducting Polymers for High‐Efficiency Organic Photovoltaics
	14.1 Introduction
	14.2 Semiconducting Polymers Based on Naphthobisthiadiazole
	14.3 Quaterthiophene–NTz Polymer: Comparison with the Benzothiadiazole Analogue
	14.4 Naphthodithiophene–NTz Polymer: Importance of the Backbone Orientation
	14.5 Optimization of PNTz4T Cells: Distribution of Backbone Orientation vs Cell Structure
	14.6 Thiophene, Thiazolothiazole–NTz Polymers: Higly Thermally Stabe Solar Cells
	14.7 Summary
	References
Chapter 15 Plasmonics for Light‐Emitting and Photovoltaic Devices
	15.1 Optical Properties of the Surface Plasmon Resonance
	15.2 High‐Efficiency Light Emissions using Plasmonics
	15.3 Mechanism for the SP Coupled Emissions
	15.4 Quantum Efficiencies and Spontaneous Emission Rates
	15.5 Applications for Organic Materials
	15.6 Device Application for Light‐Emitting Devices
	15.7 Applications to High‐Efficiency Solar Cells
	Acknowledgements
	References
Index
EULA