Defects in Organic Semiconductors and Devices

Thien-Phap Nguyen is Emeritus Professor at Nantes University, France. He has taught solid state physics, semiconductor physics and organic electronics. His research focuses on physical processes in organic semiconductors and devices.

• Abbreviations ixIntroduction xviiChapter 1. Overview of Organic Semiconductors 11.1. Organic semiconductors 21.2. Doping of organic semiconductors 41.3. Organic electronic devices 61.3.1. Architectures of organic devices 61.3.2. Organic light-emitting diodes (OLEDs) 111.3.3. Organic solar cells (OSCs or OPVs) 131.3.4. Organic field-effect transistors (OFETs) 15Chapter 2. Defects in Materials 192.1. Order and disorder 192.2. Crystalline semiconductors 202.2.1. Localized states 212.2.2. Density of states (DOS) 222.3. Amorphous semiconductors 222.3.1. Localized states 232.3.2. Density of states (DOS) 242.4. Organic semiconductors 252.4.1. Polymer structure 262.4.2. Polymer crystallinity 272.4.3. Defects in conjugated polymers 282.4.4. Defects in small-molecule crystals 292.4.5. Localized states 302.4.6. Density of states 312.5. Distribution of the energetic states 32Chapter 3. Defects and Physical Properties of Semiconductors 353.1. Carrier transport in organic semiconductors 353.1.1. Hopping conduction 373.1.2. Uniform density of states model 383.1.3. Non-uniform density of states models 393.2. Effects of defects on the carrier transport 443.2.1. Traps and recombination centers 443.2.2. Trapping mechanisms and trap parameters 463.3. Optical properties of semiconductors and defects 563.3.1. Defects and absorption 563.3.2. Defects and luminescence 59Chapter 4. Techniques for Studying Defects in Semiconductors 654.1. Electron spin resonance (ESR) 654.1.1. Basic concepts of ESR 664.1.2. Interpretation of ESR line 674.1.3. Electron nuclear double resonance (ENDOR) 684.1.4. Investigation of defects using the ESR technique 694.2. Optical techniques 724.2.1. Fluorescence spectroscopy (FL) 724.2.2. Thermally stimulated luminescence (TSL) spectroscopy 754.3. Electrical techniques 864.3.1. Thermally stimulated current (TSC) technique 874.3.2. Current-voltage measurements: space charge-limited current (SCLC) 964.3.3. Impedance spectroscopy (IS) 1104.3.4. Deep-level transient spectroscopy (DLTS) 1344.3.5. Time of flight (TOF) and charge carrier extraction by linearly increasing voltage (CELIV) techniques 152Chapter 5. Defect Origins 1595.1. Defects in organic semiconductors 1595.1.1. Structural defects 1605.1.2. Impurity defects 1605.2. Defects in organic devices 1625.2.1. Defects from the semiconductor 1635.2.2. Defects from the surface and the interface 1645.2.3. Defects from diffused impurities 168Chapter 6. Defects, Performance and Reliability of Organic Devices 1736.1. Impact of defects on the performance of organic devices 1746.1.1. Defects and efficiency of OLEDs 1746.1.2. Defects and efficiency of OPVs 1766.1.3. Defects and performance of OFETs 1816.2. Impact of defects on the stability of organic devices 1836.2.1. Overview of degradation mechanisms in organic semiconductors and devices 1846.2.2. Defects and degradation of organic semiconductor and devices 188Future Prospects 217References 223Index 249