An Introduction to Charge Carriers

Description

This book provides a semi-quantitative approach to understanding and applications of charge carriers in inorganic and organic opto-electronic and photonic devices. Featuring contributions by noted experts in the field of optoelectronics, materials and photonics, this book describes the importance of charge carriers in the operation of optoelectronic and photonic devices of both inorganic and organic semiconductors. An Introduction to Charge Carriers starts with the concept of charge carriers and their involvement in a few inorganic and organic devices, like solar cells and organic light emitting diodes (OLEDs), including those based on thermally activated and delayed fluorescence (TADF). Then it discusses the applications of charge carriers in silicon p-n junction, nanomaterials, wurtzite phases of gallium, aluminium and indium nitride devices, ion conducting polymer electrolytes, rare-earth doped glasses, organic photodetectors, and several aspects of organic and perovskite solar cells. An Introduction to Charge Carriers is an ideal book for senior undergraduate and postgraduate students and teaching and research professionals in the field of solid-state physics, material science and engineering. Contents Preface Chapter 1 Electrons and Charge Carriers Abstract 1. Introduction - Electrons 1.1. Solids 1.2. Charge Carriers 2. Semiconductors 2.1. p-n Junction 2.2. Solar Cells 2.2.1. Dissociation of Excitons in OSCs 2.3. Intersystem Crossing and Reverse Intersystem Crossing in Organic Semiconductors 2.3.1. Rate of Intersystem Crossing 2.3.2. Reverse Intersystem Crossing or Up-Conversion 2.3.3. Thermally Activated Delayed Fluorescence (TADF) in Organic Light-Emitting Diodes (Oleds) Conclusion References Chapter 2 Analytical Solutions for Drift- Diffusion Equations Describing Charge-Carrier Transport in Silicon Semiconductor Structures Abstract 1. Introduction 2. The Starting Equations 3. Regional Partitioning 4. Time Regimes 4.1. DR Collapse 4.2. Fast Partial Recovery 4.3. Slow Recovery 5. The DR Equations for Steady-State or Slow-Recovery 6. The QNR Equations 7. Topology and Notation 8. Solution to a Low-Level Steady-State Problem 9. Solution to a Low-Level Semi-Transient Problem 10. Solutions to Low-Level Fully-Transient Problems 11. Solution to a High-Level Steady-State Problem 12. Solution to a High-Level Semi-Transient Problem 13. Saturation of Peak Currents 14. Exact Mathematical Solutions for Special Cases 14.1. Open Circuit Boundary Values 14.2. Open Circuit Steady-State Solution in QNR Interior 14.3. Steady-State without Carrier Generation Conclusion References Chapter 3 Dynamics of Charge Carriers in Nanomaterials Abstract Abbreviations Major Notation Introduction THz Spectroscopy Carrier Dynamics Typical Examples of THz Conductivity in Nanomaterlas Discussions Conclusion Acknowledgments References Chapter 4 Charge Carrier Transport Within the Wurtzite Phases of the Gallium, Aluminium, and Indium Nitrides Abstract Chapter 5 Charge Carrier Dynamics in Ion Conducting Polymer Electrolytes Abstract 1. Introduction 2. Classification of Polymer Electrolytes 2.1. Plasticized Polymer Electrolytes 2.2. Gel Polymer Electrolytes 2.3. Composites Polymer Electrolytes 2.4. Rubbery Electrolytes 2.5. Polymer Salt-Complex or Dry Solid Polymer Electrolytes (SPEs) 3. Ion Transport Mechanism in Polymer Electrolytes 3.1. Composition Dependent 3.2. Temperature Dependent 3.2.1. Arrhenius Model 3.2.2. Vogel-Tamman-Fulcher (VTF) Model 3.2.3. William-Landel-Ferry (WLF) Model 3.2.4. Free Volume Model 3.2.5. Dynamic Bond Percolation (DBP) Model 3.3 Models/Methods 3.3.1. Rice and Roth Model 3.3.2. Schutt and Gerdes Model 3.3.3. Bandara and Mellander (B-M) Model 3.3.4. Greenbaum’s Formula 3.3.4.1. Determination of n and μ in a Ionic Liquid Doped Poly(Ethylene Oxide), PEO Based Polymer Electrolyte System 3.3.4.1.1. At Room Temperature 3.3.4.1.2. Temperature Dependence 3.3.4.2. Determination of n and μ in a Ionic Liquid Doped Poly(Ethylene Oxide), PEO Based Polymer Electrolyte System 3.3.4.3. Determination of n and μ in a Poly(Ethylene Oxide), PEO Based Polymer Electrolyte Doped with Ionic Liquid 3.3.5. Trukhan’s Model 3.3.5.1. Determination of n and μ in an Ionic Liquid Doped Poly(Ethylene Oxide), PEO Based Polymer Electrolyte System 3.3.5.1.1. At Room Temperature 3.3.5.1.2. Temperature Dependence 3.3.5.2. Determination of n and μ in an Ionic Liquid Doped Poly(Ethylene Oxide), PEO Based Polymer Electrolyte System Conclusion References Chapter 6 Energy Exchange Processes in Rare-Earth Ion Doped Glasses and Their Importance in Lasing and Signal Amplification Abstract 1. Background Models 2. Excitonic States in Dielectric, Spontaneous (PL) and Stimulated Emission Processes 2.1. Resonant Stoke and Anti-Stoke Transitions in RE-Ion Doped Glasses 2.2. A Summary of D-D, Q-D, Q-D Model Equation and Energy Transfer Characterisation in RE-Ion and RE-TM Ion Doped Glasses and Crystals 2.3. Cross-Relaxation (CR) and Related Up- and Down Conversion in RE3+-Ions 2.3.1. Definition and Charaterisation 2.3.2. Pr3+-Yb3+ Ion Co-Doped Fluoride Glasses and Fibres 2.3.3. Er3+-Ce3+-Yb3+ Doped Glasses and Fibres 2.3.4. Examples of Quantum Cutting (QC) Transitions for Energy Exchange in Multiple RE-Ions Doped Tellurite Glasses 2.3.5. Control of the Oxidation States and Photodarkening in Optical Fibre Lasers 3. Controlling the Oxidation States of RE-Ions in Planar Waveguide Fabrication Using Ultra-Fast Lasers 4. Summary of Applications in Solar Energy Harvesting Using RE-Ion Doped Materials Conclusion Acknowledgments Conflict of Interest References Chapter 7 Dynamics of Charge Carriers in Spectral Selective Organic Photodetectors Abstract 1. Introduction 2. Device Physics of Organic Photodetectors 3. Generation of Charge Carriers in Spectral Selective OPDs 3.1. OPDs with an Optical Depletion/Absorption Heterostructure 3.2. Profiles of Charge Generation in Spectral Selective OPDs 3.3. Spectral Selective Response Behaviors 3.4. Spectral Selective OPDs 4. Charge Collection in Narrowband OPDs 4.1. Optical Field Distribution 4.2. Effect of Space Charge Buildup 4.3. Narrowband Near-Infrared Photodetection Conclusion References Chapter 8 Charge Generation Dynamics in Organic and Perovskite Solar Cells Abstract 1. Introduction 2. Mechanism and Rate of Intersystem Crossing 3. Exciton-Spin-Orbit-Phonon Operator 4. Intersystem Crossing Rate 5. Exciton Dissociation at the D-A Interface in Bulk Heterojunction Organic Solar Cells 6. Exciton Generation in OSCs 7. Exciton Diffusion 8. Charge Transfer Exciton Recombination Dynamics in OSCs 9. Charge Transport and Recombination in Perovskite Solar Cells 10. Open-Circuit Voltage and Bimolecular Recombination Coefficient in PSCs Conclusion References Chapter 9 Optimal Performance of Organic Solar Cells: Charge Carrier Effects Abstract Introduction Methods Optical Transfer Matrix Method Drift-Diffusion Model Results and Discussion Electric Field Exciton Generation Rate Charge Carrier Recombination Rates Power Conversion Efficiency Conclusion References Chapter 10 Enhancing Power Conversion Efficiency of Bulk Hetero Junction (BHJ) Organic Solar Cells (OSCS) by Simulation Abstract 1. Introduction 2. Simulation of Efficient and Stable Non-Fullerene Acceptor Based Ternary BHJ OSCs 2.1. Simulation of PCE of a TOSC 2.1.1. Simulation of Jsc 2.1.2. Simulation of Voc 2.1.3. Simulation of FF 2.2. Simulation of PCE of a TOSC with Non-fullerene Acceptor 2.2.1. Simulation of Jsc 2.2.2. Simulation of Voc 2.2.3. Simulation of FF 3. An Alternate Method of Simulating PCE 3.1. Photon Absorption Efficiency (,𝜼-𝒂𝒃𝒔.) 3.1.1. Optical Admittance Analysis Method (OAAM) for Calculation of ,𝑮. 3.1.2. Optical Transfer Matrix Method (OTMM) for Calculation of ,𝑮. 3.2. Exciton Dissociation Efficiency (,𝜼-𝒅𝒊𝒔.) 3.3. Charge Carrier Extraction Efficiency (,𝜼-𝒆𝒙𝒕.) 3.4. Power Conversion Efficiency of an OSC 4. Exciton Generation in NFA BHJ OSCs 4.1. Theory 4.2. Simulation 4.2.1. Electric Field and Exciton Generation Rate Distributions in OSC2 4.2.2. Optimization of the Thicknesses of Each Layer 4.2.2.1. Optimization of the Structure of OSC2 4.2.2.2. Optimization of the Structure of OSC4 4.2.2.3. Optimization of the Structure of OSC5 Conclusion References Editor’s Contact Information Index Blank Page