Principles of Solar Cells, LEDs and Related Devices: The Role of the PN Junction

The second edition of the text that offers an introduction to the principles of solar cells and LEDs, revised and updated  The revised and updated second edition of Principles of Solar Cells, LEDs and Related Devices offers an introduction to the physical concepts required for a comprehensive understanding of p-n junction devices, light emitting diodes and solar cells. The author – a noted expert in the field – presents information on the semiconductor and junction device fundamentals and extends it to the practical implementation of semiconductors in both photovoltaic and LED devices. In addition, the text offers information on the treatment of a range of important semiconductor materials and device structures including OLED devices and organic solar cells.   This second edition contains a new chapter on the quantum mechanical description of the electron that will make the book accessible to students in any engineering discipline. The text also includes a new chapter on bipolar junction and junction field effect transistors as well as expanded chapters on solar cells and LEDs that include more detailed information on high efficiency devices. This important text: Offers an introduction to solar cells and LEDs, the two most important applications of semiconductor diodes Provides a solid theoretical basis for p-n junction devices Contains updated information and new chapters including better coverage of LED out-coupling design and performance and improvements in OLED efficiency Presents student problems at the end of each chapter and worked example problems throughout the text Written for students in electrical engineering, physics and materials science and researchers in the electronics industry, Principles of Solar Cells, LEDs and Related Devices is the updated second edition that offers a guide to the physical concepts of p-n junction devices, light emitting diodes and solar cells.

Table of Contents:
Introduction xi Acknowledgements xv 1 Introduction to Quantum Mechanics 1 1.1 Introduction 2 1.2 The Classical Electron 2 1.3 Two Slit Electron Experiment 4 1.4 The Photoelectric Effect 7 1.5 Wave Packets and Uncertainty 10 1.6 The Wavefunction 12 1.7 The Schrödinger Equation 14 1.8 The Electron in a One-Dimensional Well 18 1.9 Electron Transmission and Reflection at Potential Energy Step 24 1.10 Expectation Values 26 1.11 Spin 26 1.12 The Pauli Exclusion Principle 29 1.13 Summary 30 Further Reading 32 Problems 33 2 Semiconductor Physics 37 2.1 Introduction 38 2.2 The Band Theory of Solids 38 2.3 Bloch Functions 40 2.4 The Kronig–Penney Model 42 2.5 The Bragg Model 47 2.6 Effective Mass 48 2.7 Number of States in a Band 50 2.8 Band Filling 52 2.9 Fermi Energy and Holes 53 2.10 Carrier Concentration 55 2.11 Semiconductor Materials 65 2.12 Semiconductor Band Diagrams 67 2.13 Direct Gap and Indirect Gap Semiconductors 72 2.14 Extrinsic Semiconductors 74 2.15 Carrier Transport in Semiconductors 79 2.16 Equilibrium and Non-Equilibrium Dynamics 83 2.17 Carrier Diffusion and the Einstein Relation 86 2.18 Quasi-Fermi Energies 88 2.19 The Diffusion Equation 91 2.20 Traps and Carrier Lifetimes 94 2.21 Alloy Semiconductors 98 2.22 Summary 100 References 103 Further Reading 103 Problems 105 3 The p–n Junction Diode 111 3.1 Introduction 112 3.2 Diode Current 113 3.3 Contact Potential 117 3.4 The Depletion Approximation 119 3.5 The Diode Equation 127 3.6 Reverse Breakdown and the Zener Diode 139 3.7 Tunnel Diodes 141 3.8 Generation/Recombination Currents 143 3.9 Metal–Semiconductor Junctions 145 3.10 Heterojunctions 156 3.11 Alternating Current (AC) and Transient Behaviour 157 3.12 Summary 159 Further Reading 160 Problems 161 4 Photon Emission and Absorption 165 4.1 Introduction to Luminescence and Absorption 166 4.2 Physics of Light Emission 167 4.3 Simple Harmonic Radiator 169 4.4 Quantum Description 170 4.5 The Exciton 174 4.6 Two-Electron Atoms 176 4.7 Molecular Excitons 184 4.8 Band-to-Band Transitions 186 4.9 Photometric Units 190 4.10 Summary 194 References 195 Further Reading 195 Problems 197 5 p–n Junction Solar Cells 201 5.1 Introduction 202 5.2 Light Absorption 204 5.3 Solar Radiation 207 5.4 Solar Cell Design and Analysis 207 5.5 Thin Solar Cells, G = 0 214 5.6 Thin Solar Cells, G > 0 218 5.7 Solar Cell Generation as a Function of Depth 220 5.8 Surface Recombination Reduction 224 5.9 Solar Cell Efficiency 225 5.10 Silicon Solar Cell Technology: Wafer Preparation 230 5.11 Silicon Solar Cell Technology: Solar Cell Finishing 233 5.12 Silicon Solar Cell Technology: Advanced Production Methods 237 5.13 Thin-Film Solar Cells: Amorphous Silicon 238 5.14 Telluride/Selenide/Sulphide Thin-Film Solar Cells 245 5.15 High-efficiency Multi-junction Solar Cells 247 5.16 Concentrating Solar Systems 251 5.17 Summary 253 References 254 Further Reading 255 Problems 257 6 Light-Emitting Diodes 265 6.1 Introduction 266 6.2 LED Operation and Device Structures 267 6.3 Emission Spectrum 269 6.4 Non-radiative Recombination 271 6.5 Optical Outcoupling 272 6.6 GaAs LEDs 275 6.7 GaAs1−x Px LEDs 277 6.8 Double Heterojunction Alx Ga1−x As LEDs 278 6.9 AlGaInP LEDs 285 6.10 Ga1−xInxN LEDs 286 6.11 LED Structures for Enhanced Outcoupling and High Lumen Output 294 6.12 Summary 299 References 300 Further Reading 301 Problems 303 7 Organic Semiconductors, OLEDs, and Solar Cells 307 7.1 Introduction to Organic Electronics 308 7.2 Conjugated Systems 309 7.3 Polymer OLEDs 314 7.4 Small-Molecule OLEDs 320 7.5 Anode Materials 323 7.6 Cathode Materials 324 7.7 Hole Injection Layer 325 7.8 Electron Injection Layer 326 7.9 Hole Transport Layer 326 7.10 Electron Transport Layer 328 7.11 Light-Emitting Material Processes 330 7.12 Host Materials 332 7.13 Fluorescent Dopants 334 7.14 Phosphorescent and Thermally Activated Delayed Fluorescence Dopants 335 7.15 Organic Solar Cells 340 7.16 Organic Solar Cell Materials 344 7.17 Summary 349 References 352 Further Reading 352 Problems 353 8 Junction Transistors 359 8.1 Introduction 359 8.2 Bipolar Junction Transistor 360 8.3 Junction Field-Effect Transistor 367 8.4 BJT and JFET Symbols and Applications 371 8.5 Summary 372 Further Reading 373 Problems 375 Appendix 1: Physical Constants 377 Appendix 2: Derivation of the Uncertainty Principle 379 Appendix 3: Derivation of Group Velocity 383 Appendix 4: The Boltzmann Distribution Function 385 Appendix 5: Properties of Semiconductor Materials 391 Index 392

About the Author :
Adrian Kitai, PhD, is Professor in the Departments of Materials Science and Engineering, and Engineering Physics at McMaster University (Canada). He is a world leader in electroluminescent science and technology. His research interests include solar cell materials and devices, and LED materials and devices, and he is involved in start-up companies in both solar cells and display systems using LED devices.