The ELFNET Book on Failure Mechanisms, Testing Methods, and Quality Issues of Lead-Free Solder Interconnects is the work of the European network ELFNET which was founded by the European Commission in the 6th Framework Programme. It brings together contributions from the leading European experts in lead-free soldering. The limited validity of testing methods originating from tin-lead solder was a major point of concern in ELFNET members' discussions. As a result, the network's reliability group decided to bring together the material properties of lead-free solders, as well as the basics of material science, and to discuss their influence on the procedures for accelerated testing. This has led to a matrix of failure mechanisms and their activation and, as a result, to a comprehensive coverage of the scientific background and its applications in reliability testing of lead-free solder joints. The ELFNET Book on Failure Mechanisms, Testing Methods, and Quality Issues of Lead-Free Solder Interconnects is written for scientists, engineers and researchers involved with lead-free electronics.

Dielectric Polymer Nanocomposites provides the first in-depth discussion of nano-dielectrics, an emerging and fast moving topic in electrical insulation. The text begins with an overview of the background, principles and promise of nanodielectrics, followed by a discussion of the processing of nanocomposites and then proceeds with special considerations of clay based processes, mechanical, thermal and electric properties and surface properties as well as erosion resistance. Carbon nanotubes are discussed as a means of creation of non linear conductivity, the text concludes with a industrial applications perspective.

Carbon nanotubes (CNTs) and Boron nitride nanotubes (BNNTs) are part of the so-called B-C-N material system, which includes novel nanostructures of carbon (C), doped-carbon, boron (B), boron nitride (BN), carbon nitride (CNx), boron-carbon nitride (BxCyNz), and boron carbide (BxCy). BNNTs and CNTs are structurally similar and share extraordinary mechanical properties, but they differ in chemical, biological, optical, and electrical properties. Therefore, hybrid nanotubes constructed of B, C, N elements are expected to form a new class of nanotubes with tunable properties between those of CNTs and BNNTs. In addition, these B-C-N nanostructures will further enhance and complement the applications of CNTs and BNNTs. With contributions from leading experts, B-C-N Nanotubes and Related Nanostructures is the first book to cover all theoretical and experimental aspects of this emerging material system, and meets the need for a comprehensive summary of the tremendous advances in research on B-C-N materials in recent years.

The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science. The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics. Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist. Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned. Readership: Polymer scientists, or scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students

This book is loosely based on a Multidisciplinary University Research Initiative (MURI) project and a few supplemental projects sponsored by the Of?ce of Naval Research (ONR) during the time frame of 2004-2009. The initial technical scope and vision of the MURI project was formulated by Drs. Larry Cooper and Joel Davis, both program of?cers at ONR at the time. The unifying theme of this MURI project and its companionefforts is the concept of cellular nonlinear/neuralnetwork (CNN) technology and its various extensions and chip implementations, including nanoscale sensors and the broadening ?eld of cellular wave computing. In recent years, CNN-based vision system drew much attention from vision scientists to device technologists and computer architects. Due to its early - plementation in a two-dimensional (2D) topography, it found success in early vision technologyapplications, such as focal-plane arrays, locally adaptable sensor/ processor integration, resulting in extremely high frame rates of 10,000 frames per second. More recently it drew increasing attention from computer architects, due to its intrinsic local interconnect architecture and parallel processing paradigm. As a result, a few spin-off companies have already been successful in bringing cel- lar wave computing and CNN technology to the market. This book aims to capture some of the recent advances in the ?eld of CNN research and a few select areas of applications.

This critical volume examines the different methods used for the synthesis of a great number of photocatalysts, including TiO2, ZnO and other modified semiconductors, as well as characterization techniques used for determining the optical, structural and morphological properties of the semiconducting materials. Additionally, the authors discuss photoelectrochemical methods for determining the light activity of the photocatalytic semiconductors by means of measurement of properties such as band gap energy, flat band potential and kinetics of hole and electron transfer. Photocatalytic Semiconductors: Synthesis, Characterization and Environmental Applications provide an overview of the semiconductor materials from first- to third-generation photocatalysts and their applications in wastewater treatment and water disinfection. The book further presents economic and toxicological aspects in the production and application of photocatalytic materials.

This text on the electrical, optical, magnetic, and thermal properties of materials stresses concepts rather than mathematical formalism. Suitable for advanced undergraduates, it is intended for materials and electrical engineers who want to gain a fundamental understanding of alloys, semiconductor devices, lasers, magnetic materials, and so forth. The book is organized to be used in a one-semester course; to that end each section of applications, after the introduction to the fundamentals of electron theory, can be read independently of the others. Many examples from engineering practice serve to provide an understanding of common devices and methods. Among the modern applications covered are: high-temperature superconductors, optoelectronic materials, semiconductor device fabrication, xerography, magneto-optic memories, and amorphous ferromagnetics. The fourth edition has been revised and updated with an emphasis on the applications sections, which now cover devices of the next generation of electronics.

This book covers all the steps in order to fabricate a lab-on-a-chip device starting from the idea, the design, simulation, fabrication and final evaluation. Additionally, it includes basic theory on microfluidics essential to understand how fluids behave at such reduced scale. Examples of successful histories of lab-on-a-chip systems that made an impact in fields like biomedicine and life sciences are also provided. This book also: * Provides readers with a unique approach and toolset for lab-on-a-chip development in terms of materials, fabrication techniques, and components * Discusses novel materials and techniques, such as paper-based devices and synthesis of chemical compounds on-chip * Covers the four key aspects of development: basic theory, design, fabrication, and testing * Provides readers with a comprehensive list of the most important journals, blogs, forums, and conferences where microfluidics and lab-on-a-chip news, methods, techniques and challenges are presented and discussed, as well as a list of companies providing design and simulation support, components, and/or developing lab-on-a-chip and microfluidic devices.

This monograph solely investigates the Einstein's Photoemission(EP) from Heavily Doped(HD) Quantized Structures on the basis of newly formulated electron dispersion laws. The materials considered are quantized structures of HD non-linear optical, III-V, II-VI, Ge, Te, Platinum Antimonide, stressed materials, GaP, Gallium Antimonide, II-V, Bismuth Telluride together with various types of HD superlattices and their Quantized counterparts respectively. The EP in HD opto-electronic materials and their nanostructures is studied in the presence of strong light waves and intense electric fields that control the studies of such quantum effect devices. The suggestions for the experimental determinations of different important physical quantities in HD 2D and 3D materials and the importance of measurement of band gap in HD optoelectronic materials under intense built-in electric field in nano devices and strong external photo excitation (for measuring physical properties in the presence of intense light waves which alter the electron energy spectra) have also been discussed in this context. The influence quantizing magnetic field, on the EP of the different HD quantized structures (quantum wells, quantum well HD superlattices and nipi structures) under different physical conditions has been investigated. This monograph contains 100 open research problems which form the integral part of the text and are useful for both Ph.D aspirants and researchers in the fields of materials science, condensed matter physics, solid-state sciences, nano-science and technology and allied fields in addition to the graduate courses in modern semiconductor nanostructures offered in different Universities and Institutes.

This comprehensive text collects the progress made in recent years in the fabrication, processing, and performance of organic nanophotonic materials and devices. The first part of the book addresses photonic nanofabrications in a chapter on multiphoton processes in nanofabrication and microscopy imaging. The second part of the book is focused on nanoscale light sources for integrated nanophotonic circuits, and is composed of three chapters on organic nano/microcavities, organic laser materials, and polymer light-emitting electrochemical cells (LECs). The third part is focused on the interactions between light and matter and consists in three chapters, including the propagation of light in organic nanostructures and photoswitches based on nonlinear optical polymer photonic crystals and photoresponsive molecules, respectively. The final chapter of this book introduces the integration of miniaturized photonic devices and circuits with various organic nanophotonic elements. The practical case studies demonstrate how the latest applications actually work, while tables throughout the book summarize key information and diagrams and figures help readers to grasp complex concepts and designs. The references at the end of each chapter can be used as the gateway to the relevant literature in the field. Moreover, this book helps researchers to advance their own investigations to develop the next generation of miniaturized devices for information processing, efficient energy conversion, and highly accurate sensing. Yong Sheng Zhao, PhD, is a Professor at the Institute of Chemistry, Chinese Academy of Sciences (ICCAS), China.

Strain Effect in Semiconductors: Theory and Device Applications presents the fundamentals and applications of strain in semiconductors and semiconductor devices that is relevant for strain-enhanced advanced CMOS technology and strain-based piezoresistive MEMS transducers. Discusses relevant applications of strain while also focusing on the fundamental physics pertaining to bulk, planar, and scaled nano-devices. Hence, this book is relevant for current strained Si logic technology as well as for understanding the physics and scaling for future strained nano-scale devices.

This book is an introduction to the fundamentals of emerging non-volatile memories and provides an overview of future trends in the field. Readers will find coverage of seven important memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), Multiferroic RAM (MFRAM), Phase-Change Memories (PCM), Oxide-based Resistive RAM (RRAM), Probe Storage, and Polymer Memories. Chapters are structured to reflect diffusions and clashes between different topics. Emerging Non-Volatile Memories is an ideal book for graduate students, faculty, and professionals working in the area of non-volatile memory. This book also: Covers key memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), and Multiferroic RAM (MFRAM), among others. Provides an overview of non-volatile memory fundamentals. Broadens readers' understanding of future trends in non-volatile memories.

The influence of size effects on the properties of nanostructures is subject of this book. Size and interfacial effects in oxides, semiconductors, magnetic and superconducting nanostructures, from very simple to very complex, are considered. The most general meaning is assumed for size effects, including not only the influence of a reduced dimension/dimensionality, but also specific interfacial effects. Preparation and characterization tools are explained for various nanostructures. The specific applications are discussed with respect to size-related properties. A logic implication of type phenomenon-property-material-application is envisaged throughout this work.

"Solid-State Theory - An Introduction" is a textbook for graduate students of physics and material sciences. Whilst covering the traditional topics of older textbooks, it also takes up new developments in theoretical concepts and materials that are connected with such breakthroughs as the quantum-Hall effects, the high-Tc superconductors, and the low-dimensional systems realized in solids. Thus besides providing the fundamental concepts to describe the physics of the electrons and ions comprising the solid, including their interactions, the book casts a bridge to the experimental facts and gives the reader an excellent insight into current research fields. A compilation of problems makes the book especially valuable to both students and teachers.

Nanoscale Magnetic Materials and Applications covers exciting new developments in the field of advanced magnetic materials. Readers will find valuable reviews of the current experimental and theoretical work on novel magnetic structures, nanocomposite magnets, spintronic materials, domain structure and domain-wall motion, in addition to nanoparticles and patterned magnetic recording media. Cutting-edge applications in the field are described by leading experts from academic and industrial communities. These include new devices based on domain wall motion, magnetic sensors derived from both giant and tunneling magnetoresistance, thin film devices in micro-electromechanical systems, and nanoparticle applications in biomedicine. In addition to providing an introduction to the advances in magnetic materials and applications at the nanoscale, this volume also presents emerging materials and phenomena, such as magnetocaloric and ferromagnetic shape memory materials, which motivate future development in this exciting field. Nanoscale Magnetic Materials and Applications also features a foreword written by Peter Grunberg, recipient of the 2007 Nobel Prize in Physics.

This unique book provides an up-to-date overview of the concepts behind lead-free soldering techniques. Readers will find a description of the physical and mechanical properties of lead-free solders, in addition to lead-free electronics and solder alloys. Additional topics covered include the reliability of lead-free soldering, tin whiskering and electromigration, in addition to emerging technologies and research.

This book deals with the Effective Electron Mass (EEM) in low dimensional semiconductors. The materials considered are quantum confined non-linear optical, III-V, II-VI, GaP, Ge, PtSb2, zero-gap, stressed, Bismuth, carbon nanotubes, GaSb, IV-VI, Te, II-V, Bi2Te3, Sb, III-V, II-VI, IV-VI semiconductors and quantized III-V, II-VI, IV-VI and HgTe/CdTe superlattices with graded interfaces and effective mass superlattices. The presence of intense electric field and the light waves change the band structure of optoelectronic semiconductors in fundamental ways, which have also been incorporated in the study of the EEM in quantized structures of optoelectronic compounds that control the studies of the quantum effect devices under strong fields. The importance of measurement of band gap in optoelectronic materials under strong electric field and external photo excitation has also been discussed in this context. The influence of crossed electric and quantizing magnetic fields on the EEM and the EEM in heavily doped semiconductors and their nanostructures is discussed. This book contains 200 open research problems which form the integral part of the text and are useful for both Ph. D aspirants and researchers in the fields of solid-state sciences, materials science, nanoscience and technology and allied fields in addition to the graduate courses in modern semiconductor nanostructures. The book is written for post graduate students, researchers and engineers, professionals in the fields of solid state sciences, materials science, nanoscience and technology, nanostructured materials and condensed matter physics.

The brief primarily focuses on the performance analysis of CNT based interconnects in current research scenario. Different CNT structures are modeled on the basis of transmission line theory. Performance comparison for different CNT structures illustrates that CNTs are more promising than Cu or other materials used in global VLSI interconnects. The brief is organized into five chapters which mainly discuss: (1) an overview of current research scenario and basics of interconnects; (2) unique crystal structures and the basics of physical properties of CNTs, and the production, purification and applications of CNTs; (3) a brief technical review, the geometry and equivalent RLC parameters for different single and bundled CNT structures; (4) a comparative analysis of crosstalk and delay for different single and bundled CNT structures; and (5) various unique mixed CNT bundle structures and their equivalent electrical models.

It has been noted several times previously that the Rare Earths (RE), a sequence of elements with atomic numbers in the range from 58 (Ce) to 71 (Lu), are neither earths nor particularly rare. They are metals, whose ores are often found together with oxides of the "alkaline earths" (Ca, Mg), staples of the building industry, th while Cerium, for example, is the 25 most abundant element in the Earth's crust. However, the chemical similarity of all REs to each other and to Lanthanum, reflected in their alternative descriptor, Lanthanoids, made extraction of the separate elements difficult until technical advances in the 1960s kick-started the modern era of RE science. The most widespread commercial use of RE metals at present is in the prod- tion of super-strong permanent magnets, containing Neodymium: check your refrigerator door for an example. RE ferromagnetism arises from the angular momentum of electrons in partially filled 4f atomic shells. In chemical compounds of RE with non-metals, the 4f shell is surrounded by filled 5s and 5p orbitals, 1 2 while bonding involves the outerlying 5d and 6s electrons, resulting (usually) in 3+ 3+ a RE ion that is chemically similar to La . (RE may also be found in a divalent charge state, with an 'extra' electron in the 5d shell. ) Hence the sequence of 3+ 3+ trivalent ions from Ce to Yb is characterised by a 4f shell occupation that rises from 1 to 13 electrons.

This book covers important aspects of modern optical communication. It is intended to serve both students and professionals. Consequently, a solid coverage of the necessary fundamentals is combined with an in-depth discussion of recent relevant research results. The book has grown from lecture notes over the years, starting 1992. It accompanies my present lectures Optical Communication A (Fundamentals), B (Mode Coupling), C (Modulation Formats) and D (Selected Topics) at the University of Paderborn, Germany. I gratefully acknowledge contributions to this book from Dr. Timo Pfau, Dr. David Sandel, Dr. Sebastian Hoffmann and Mohamed El-Darawy. Contents Contents 1 Introduction............................................................................ . . 1 2 Optical Waves in Fibers and Components.......................................3 2. 1 Electromagnetic Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. 1. 1 Maxwell's Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. 1. 2 Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. 1. 3 Wave Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. 1. 4 Homogeneous Plane Wave in Isotropic Homogeneous Medium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2. 1. 5 Power and Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. 2 Dielectric Waveguides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2. 2. 1 Dielectric Slab Waveguide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2. 2. 2 Cylindrical Dielectric Waveguide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2. 3 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 2. 3. 1 Representing States-of-Polarization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 2. 3. 2 Anisotropy, Index Ellipsoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2. 3. 3 Jones Matrices, Muller Matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 2. 3. 4 Monochromatic Polarization Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 2. 3. 5 Polarization Mode Dispersion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 2. 4 Linear Electrooptic Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 2. 4. 1 Phase Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 2. 4. 2 Soleil-Babinet Compensator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 2. 5 Mode Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 2. 5. 1 Mode Orthogonality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 2. 5. 2 Mode Coupling Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The great interest in photonic crystals and their applications in the last 15 years is being expressed in the publishing of a large number of monographs, collections, textbooks and tutorials, where existing knowledge concerning - eration principles of photonic crystal devices and microstructured ?bers, their mathematicaldescription,well-knownandnovelapplicationsofsuchtechno- gies in photonics and optical communications are presented. They challenges authors of new books to cover the gaps still existing in the literature and highlight and popularize of already known material in a new and original manner. Authorsofthisbookbelievethatthenextsteptowardswideapplicationof photoniccrystalsisthesolutionofmanypracticalproblemsofdesignandc- putation of the speci?c photonic crystal-based devices aimed at the speci?c technicalapplication.Inordertomakethisstep,itisnecessarytoincreasethe number of practitioners who can solve such problems independently. The aim of this book is to extend the group of researchers, developers and students, who could practically use the knowledge on the physics of photonic crystals together with the knowledge and skills of independent calculation of basic characteristics of photonic crystals and modeling of various elements of - tegrated circuits and optical communication systems created on the basis of photonic crystals. The book is intended for quali?ed readers, specialists in the ?eld of optics and photonics, students of higher courses, master degree students and PhD students. As an introduction to the snopest, the book contains the basics of wave optics and radiation propagation in simple guiding media such as planar waveguides and step-index ?bers.

This book takes a "bottom-up" approach, beginning with atoms and molecules - molecular building blocks - and assembling them to build nanostructured materials. Coverage includes Carbon Nanotubes, Nanowires, and Diamondoids. The applications presented here will enable practitioners to design and build nanometer-scale systems. These concepts have far-reaching implications: from mechanical to chemical processes, from electronic components to ultra-fine sensors, from medicine to energy, and from pharmaceuticals to agriculture and food.

Lead-free solders are used extensively as interconnection materials in electronic assemblies and play a critical role in the global semiconductor packaging and electronics manufacturing industry. Electronic products such as smart phones, notebooks and high performance computers rely on lead-free solder joints to connect IC chip components to printed circuit boards. Lead Free Solder: Mechanics and Reliability provides in-depth design knowledge on lead-free solder elastic-plastic-creep and strain-rate dependent deformation behavior and its application in failure assessment of solder joint reliability. It includes coverage of advanced mechanics of materials theory and experiments, mechanical properties of solder and solder joint specimens, constitutive models for solder deformation behavior; numerical modeling and simulation of solder joint failure subject to thermal cycling, mechanical bending fatigue, vibration fatigue and board-level drop impact tests.

The book summarizes and compares recent advancements in the development of novel lateral power transistors (LDMOS devices) for integrated circuits in power electronic applications. In its first part, the book motivates the necessity for lateral power transistors by a top-down approach: First, it presents typical energy conversion applications in modern industrial, automotive and consumer electronics. Next, it introduces common circuit topologies suitable for these applications, and discusses the feasibility for monolithic integration. Finally, the combination of power and logic functionality on a single chip is motivated and the requirements and limitations for the power semiconductor devices are deduced. The second part describes the evolution of lateral power transistors over the past decades from the simple pin-type concept to double-acting RESURF topologies. It describes the principle of operation for these LDMOS devices and discusses limitations of lateral power devices. Moreover, figures-of-merit are presented which can be used to evaluate the performance of the novel lateral power transistors described in this book with respect to the LDMOS devices. In the last part, [..] the fundamental physical concepts including charge compensation and trench gate topologies are discussed. Also, the status of research in LDMOS devices on silicon carbide is presented. Advantages and drawbacks for each of these integration approaches are summarized, and the feasibility with respect to power electronic applications is evaluated.

This thesis introduces a series of novel, non-conjugated polyarylether hosts that are not subject to the triplet-energy limitations of traditional conjugated polymer hosts. As a result of this major breakthrough, the long-standing problem of triplet energy back transfer has now been overcome, making it possible to design high-efficiency electrophosphorescent polymers (PhPs), especially the blue and all-phosphorescent white ones. In addition, the author proposes a spiro-linked hyperbranched architecture for PhPs to inhibit the undesired triplet energy back transfer process in low triplet-energy hosts. The work in this thesis provides vital new insights into the design of PhPs and has led to several publications in high-profile journals.