Nanostructured Energy Devices : Foundations of Carrier Transport

This is the second title in a series that analyzes the fundamental concepts, properties, and key applications of energy devices made using organic and inorganic solution-processed thin film and nanostructured materials, including hybrid and organic solar cells, electrochemical batteries, diodes, LEDs and OLEDs, transistors, and the direct conversion of solar radiation to chemical fuels. This volume presents the physics of carrier transport and semiconductor device modelling, including injection and mechanisms of contacts, the utilization of disordered materials such as organic materials, and important topics such as the transistor configuration and the frequency domain characterization. Cover 1 Half Title 2 Title 4 copyright 5 Contents 6 Preface 8 About the Author 10 Chapter 1 Carrier Injection and Drift Transport 12 1.1 Transport by Drift in the Electrical Field 12 1.2 Injection at Contacts 15 1.3 The Metal-­Insulator-­Metal Model 21 1.4 The Time-­of-­Flight Method 25 General References 28 References 28 Chapter 2 Diffusion Transport 32 2.1 Diffusion in the Random Walk Model 32 2.2 Macroscopic Diffusion Equation 37 2.3 The Diffusion Length 38 2.4 Chemical Diffusion Coefficient and the Thermodynamic Factor 40 General References 43 References 44 Chapter 3 Drift­Diffusion Transport 46 3.1 General Transport Equation in Terms of Electrochemical Potential 46 3.2 The Transport Resistance 47 3.3 The Einstein Relation 51 3.4 Drift-­Diffusion Equations 52 3.5 Ambipolar Diffusion Transport 54 3.6 Relaxation of Injected Charge 56 3.7 Transient Current in Insulator Layers 59 3.8 Modeling Transport Problems 61 General References 66 References 66 Chapter 4 Transport in Disordered Media 70 4.1 Multiple Trapping and Hopping Transport 70 4.2 Transport by Hopping in a Single Level 74 4.3 Trapping Factors in the Kinetic Constants 76 4.4 Two-­Level (Single-­Trap) Model 80 4.5 Multiple Trapping in Exponential DOS 82 4.6 Activated Transport in a Gaussian DOS 85 4.7 Multiple Trapping in the Time Domain 88 4.8 Hopping Conductivity 92 4.9 The Transport Energy 93 4.10 Variable Range Hopping 95 General References 98 References 99 Chapter 5 Thin Film Transistors 104 5.1 Organic Thin Film Transistors 104 5.2 Carrier Density in the Channel 108 5.3 Determination of the DOS in Thin Film Transistor Configuration 109 5.4 Current-­Voltage Characteristics 114 5.5 The Mobility in Disordered Semiconductors 119 5.6 Electrochemical Transistor 121 General References 123 References 123 Chapter 6 Space-Charge-Limited Transport 128 6.1 Space­Charge-Limited Current 128 6.2 Injected Carrier Capacitance in SCLC 132 6.3 Space Charge in Double Injection 137 General References 139 References 140 Chapter 7 Impedance and Capacitance Spectroscopies 142 7.1 Frequency Domain Measurements 142 7.2 Dielectric Relaxation Functions 145 7.3 Resistance and Capacitance in Equivalent Circuit Models 149 7.4 Relaxation in Time Domain 155 7.5 Universal Properties of the Frequency-­Dependent Conductivity 160 7.6 Electrode Polarization 163 General References 166 References 166 Appendix A 170 A.1 Physical Constants and Conversion Factors 170 A.2 General List of Acronyms 171 A.3 Acronyms for Materials 172 Index 174 The second volume, Foundations of Carrier Transport, presents a catalogue of the physics of carrier transport in semiconductors with a view to energy device models. We systematically explain the diffusion-drift model that is central to solar cell operation, the different responses of band bending and electrical field distribution that occur when a voltage is applied to a device with contacts and the central issue of injection and mechanisms of contacts. We describe the carrier transport in disordered materials that often appear as good candidates for easily processed solar cells. There are also excursions into other important topics such as the transistor configuration and the frequency domain techniques as Impedance Spectroscopy that produce central experimental tools for the characterization of the devices. "This is the second book in a series that analyzes the fundamental concepts, properties, and key applications of energy devices made using organic and inorganic solution-processed thin film and nanostructured materials, including hybrid and organic solar cells, electrochemical batteries, diodes, LEDs and OLEDs, transistors, and the direct conversion of solar radiation to chemical fuels. This volume presents the physics of carrier transport and semiconductor device modelling, including injection and mechanisms of contacts, the utilization of disordered materials such as organic materials, and important topics such as the transistor configuration and the frequency domain characterization."--Provided by publisher This reference analyzes the concepts, properties, and applications of energy devices made using organic and inorganic solution-processed thin film and nanostructured materials. The author presents the physics of carrier transport, semiconductor device modelling, and includes transistor configuration and the frequency domain characterization.