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• Author : Dongxiang Luo
• Publisher :Unknown
• Release Date :2018
• Total pages :229
• ISBN : 09876543XX

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Summary : Recently, thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have attracted both academic and industrial interest due to their extraordinary characteristics, such as high efficiency, low driving voltage, bright luminance, lower power consumption, and potentially long lifetime. In this chapter, various approaches to realize white OLEDs (WOLEDs) with TADF emitters have been introduced. The recent development of WOLEDs based on all TADF emitters, WOLEDs based on TADF and conventional fluorescence emitters, and WOLEDs based on TADF and phosphorescence emitters is highlighted. Particularly, the device structures, design strategies, working mechanisms, and electroluminescent processes of the representative high-performance WOLEDs with TADF emitters are reviewed. Moreover, challenges and opportunities for further enhancement of the performance of WOLEDs with TADF emitters are presented.

• Author : Jagannathan Thirumalai
• Publisher :Unknown
• Release Date :2018-09-19
• Total pages :168
• ISBN : 1789237505

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Summary : The broad vision of this book is to offer book lovers a comprehensive appraisal of topics in the global advancements of experimental facts, instrumentation, and practical applications of LED and OLED materials and their applications. The prime feature of this book is connected with LED and OLED materials approaches of fabrication, optimization limits, and their extensive technical applications. This book is comprised of seven chapters encompassing the importance of LEDs and OLEDs, the history of LEDs and OLEDs with necessary examples, the phototoxic-cum-bactericidal effect due to the usage of blue LED irradiation, DC network indoor and outdoor LED lighting, WLEDs with thermally activated delayed fluorescence emitters, tetradentate cyclometalated platinum (II) complex-based efficient organic LEDs, the impact of the use of large LED lighting loads in low-voltage networks, highly efficient OLEDs using thermally activated delayed fluorescent materials, and AlGaN deep ultraviolet LEDs. Individual chapters provide a base for the wide range of common bibliophiles in diversified fields, students, and researchers, who may conduct research pertinent to this book and will find simply explained basics as well as advanced principles of designated subjects related to these phenomena. The book was created from seven contributions from experts in the diversified fields of LED and OLED fabrication and technology from over 15 research institutes across the globe.

• Author : Hartmut Yersin
• Publisher :Unknown
• Release Date :2018-11-19
• Total pages :608
• ISBN : 3527339000

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Summary : The essential resource that offers a comprehensive understanding of OLED optimizations Highly Efficient OLEDs. Materials Based on Thermally Activated Delayed Fluorescence (TADF) offers substantial information on the working principle of OLEDs and on new types of emitting materials (organic and inorganic). As the authors explain, OLEDs that use the Singlet-Harvesting mechanism based on the molecular property of TADF work according to a new exciton harvesting principle. Thus, low-cost emitter materials, such as Cu(I) or Ag(I) complexes as well as metal-free organic molecules, have the potential to replace high-cost rare metal complexes being currently applied in OLED technology. With contributions from an international panel of experts on the topic, the text shows how the application of new TADF materials allow for the development of efficient OLED displays and lighting systems. This new mechanism is the gateway to the third-generation of luminescent materials. This important resource: Offers a state-of-the-art compilation of the latest results in the dynamically developing field of OLED materials Is edited by a pioneer in the field of OLED material technology Contains a detailed application-oriented guide to new low-cost materials for displays and lighting Puts the focus on the emerging fields of OLED technology Written for materials scientists, solid state chemists, solid state physicists, and electronics engineers, Highly Efficient OLEDs. Materials Based on Thermally Activated Delayed Fluorescence offers a comprehensive resource to the latest advances of OLEDs based on new TADF materials.

• Author : Hiroko Yamada,Shiki Yagai
• Publisher :Unknown
• Release Date :2019-05-22
• Total pages :224
• ISBN : 0429827997

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Summary : Inspired by naturally occurring light-active molecular systems such as photosynthesis, scientists have long devoted their efforts to understanding how light and molecules interact. Based on a raft of knowledge on light absorption, energy migration and electron transfer, fluorescence and phosphorescence, and various photochemical reactions, light can now be utilized for energy conversion, information storage, medical applications, and development of next-generation photofunctional materials that cannot be obtained via conventional organic synthesis. This book overviews some of the cutting-edge p-conjugated molecular and polymer materials for organic photovoltaics, artificial photosynthesis, and organic light-emitting devices. It gives insights into the interactions between light and molecules and discusses sophisticated molecular designs, self-assembly and self-organization strategies, and state-of-the-art unconventional analytical methods.

• Author : Anonim
• Publisher :Unknown
• Release Date :2018
• Total pages :229
• ISBN : 09876543XX

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Summary : Abstract : A fully non-doped all-TADF strategy is proposed to fabricate simple and efficient WOLEDs based on a novel yellow TADF emitter. Abstract : Thermally activated delayed fluorescence (TADF) emitters can harvest singlet and triplet excitons for light emission to afford highly efficient organic light-emitting diode (OLED) devices, especially for all-TADF white OLEDs (WOLEDs). However, the majority of TADF emitters suffer from concentration quenching effects and require complicated doping techniques for device fabrication. Herein, we demonstrate a yellow TADF emitter that enables non-doped OLED systems, which is beneficial for the simplification of the OLED device structure and fabrication. The non-doped yellow OLED achieves a maximum external quantum efficiency (EQE) of 16.7% at a high luminance of 3600 cd m −2, in which such a high magnitude is rarely reported. More significantly, by the combination of the yellow TADF emitter with a blue TADF emitter, a fully non-doped emissive layer (EML) strategy has been demonstrated for the fabrication of an all-TADF WOLED, in which the non-doped yellow and blue TADF emissive layers are closely stacked together without any interlayers. The fully non-doped WOLEDs show a maximum EQE of up to 19.8%, along with high quality white-light emission. This is the first report regarding the fully non-doped all-TADF WOLEDs, and the presented design strategy provides a universal route towards the fabrication of simple and efficient WOLEDs.

• Author : Shi-Jian Su,Lian Duan,Hisahiro Sasabe
• Publisher :Unknown
• Release Date :2019-11-27
• Total pages :229
• ISBN : 288963163X

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Summary : Since the invention of the first efficient organic light-emitting diodes (OLEDs) by C. T. Tang and S. VanSlyke, OLEDs have attracted close interest as a promising candidate for next-generation full-color displays and future solid-state lighting sources because of a number of advantages like high brightness and contrast, high luminous efficiency, fast response time, wide viewing angle, low power consumption, and light weight. The recombination of holes and electrons under electrical excitation typically generates 25% singlet excitons and 75% triplet excitons. For traditional fluorescent OLEDs, only 25% singlet excitons can be utilized to emit light, while the other 75% triplet excitons are generally wasted through nonradiative transition. By adopting noble metal phosphorescent complexes, an internal quantum efficiency (IQE) of 100% could be achieved by utilizing both the 25% singlet excitons and 75% triplet excitons. However, these phosphors usually contain nonrenewable and highcost iridium or platinum noble metals. Most recently, unity IQE has been readily achieved through noble metal-free purely organic emitters, such as thermally activated delayed fluorescence (TADF) emitters, hybridized local and charge-transfer state (HLCT) “hot exciton” emitters, binary- or ternary-mixed donor-acceptor exciplex emitters, and neutral p radical emitters, etc. In addition, the combination of conventional p-type hole-transport and n-type electron-transport materials in an appropriate device structure can also provide an uncommon efficiency. Both strategies are essential and attractive for high-performance and low-cost full-color displays and white OLED applications. This Research Topic mainly focus on this new generation of organic light-emitting materials and devices, including design, synthesis, and characterization of light-emitting organic molecules with tunable excited states, and their structural, electrical, and photophysical properties. Contributions relating to carrier transporting materials and corresponding device engineering are also included. Two mini reviews and thirteen original research articles by recognized academic experts in their respective fields are collected in this Research Topic, which will offer a broad perspective of noble metal-free organic light emitters, including conventional fluorescent emitters, TADF emitters, HLCT emitters, exciplex emitters, aggregation-induced emission (AIE) luminogens, and their corresponding devices. We believe this eBook should attract the attention of multidisciplinary researchers in the fields of materials science, organic synthesis, and electronic device engineering, especially for those engaged in OLED-related areas.

• Author : Anonim
• Publisher :Unknown
• Release Date :2016
• Total pages :229
• ISBN : 09876543XX

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Summary : Abstract : High efficiency, stable organic light-emitting diodes (OLEDs) based on 2-pheyl-4′-carbazole-9-H-Thioxanthen-9-one-10, 10-dioxide (TXO-PhCz) with different doping concentration are constructed. The stability of the encapsulated devices are investigated in detail. The devices with the 10 wt% doped TXO-PhCz emitter layer (EML) show the best performance with a current efficiency of 52.1 cd/A, a power efficiency of 32.7 lm/W, and an external quantum efficiency (EQE) of 17.7%. The devices based on the 10 wt%-doped TXO-PhCz EML show the best operational stability with a half-life time (LT50) of 80 h, which is 8 h longer than that of the reference devices based on fac-tris(2-phenylpyridinato)iridium(III) (Ir(ppy)3 ). These indicate excellent stability of TXO-PhCz for redox and oxidation processes under electrical excitation and TXO-PhCz can be potentially used as the emitters for OLEDs with high efficiency and excellent stability. The high-performance device based on TXO-PhCz with high stability can be further improved by the optimization of the encapsulation technology and the development of a new host for TXO-PhCz.

• Author : Nicola Armaroli,Henk J. Bolink
• Publisher :Unknown
• Release Date :2017-05-25
• Total pages :395
• ISBN : 3319593048

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Summary : The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.

• Author : Fabian Hundemer
• Publisher :Unknown
• Release Date :2020-04-08
• Total pages :375
• ISBN : 9783832550547

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Summary : Organic light-emitting diodes (OLEDs) are one of the most promising lighting technologies of the recent years not only due to their efficiency and energy saving capabilities, but also for their unique features in the realization of transparent and flexible display solutions. Thermally activated delayed fluorescence (TADF) is considered as the most promising mechanism for electroluminescence for OLED application as this allows a complete conversion of excitons to photons. In this work, strategies for the development of TADF materials for solution processed OLED devices were pursued: Isophthalonitrile- and phthalimide-based TADF emitters were chemically modified with derivatization on the acceptor and donor groups in order to study the structure-to-property relationships. A modular approach allowed the introduction of various functional groups and structural motives. Besides succeeding in attaching a TADF emitter to biomolecules and oligomers for various applications like fluorescence imaging, the optoelectronic properties were manipulated mainly with regards to the emission wavelength covering a total range of 437 nm to 541 nm with typically small increments of 2 nm. Most promising emitters were employed in solution processed OLED devices, resulting in external quantum efficiencies (EQE) of up to 16%. In addition, the tris[1,2,4]triazolo[1,3,5]triazine (TTT) core was successfully implemented as novel acceptor group for TADF emitters. Hence, a synthesis for the TTT core with peripheral donor groups was developed. The donor strength and count were identified as key drivers for the emission color (398 nm to 466 nm) and the dihedral angle as critical measure for TADF characteristics.

• Author : Jagannathan Thirumalai
• Publisher :Unknown
• Release Date :2016-11-10
• Total pages :388
• ISBN : 9535127624

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Summary : The aim of this book is to give readers a broad review of topical worldwide advancements in theoretical and experimental facts, instrumentation and practical applications erudite by luminescent materials and their prospects in dealing with different types of luminescence like photoluminescence, electroluminescence, thermo-luminescence, triboluminescence, bioluminescence design and applications. The additional part of this book deals with the dynamics, rare-earth ions, photon down-/up-converting materials, luminescence dating, lifetime, bioluminescence microscopical perspectives and prospects towards the basic research or for more advanced applications. This book is divided into four main sections: luminescent materials and their associated phenomena; photo-physical properties and their emerging applications; thermoluminescence dating: from theory to applications, and bioluminescence perspectives and prospects. Individual chapters should serve the broad spectrum of common readers of diverse expertise, layman, students and researchers, who may in this book find easily elucidated fundamentals as well as progressive principles of specific subjects associated with these phenomena. This book was created by 14 contributions from experts in different fields of luminescence and technology from over 20 research institutes worldwide.

• Author : Luiz F. R. Pereira
• Publisher :Unknown
• Release Date :2012-05-29
• Total pages :350
• ISBN : 9814267295

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Summary : This book addresses the development of OLEDs based on rare-earth and transition metal complexes, especially focusing on europium, terbium, ruthenium, and rhenium. The idea is to explain how these organic materials can be used to build OLEDs. Taking into account the actual state of the art and the expected pathways, the book proposes further developments in the field. It presents intensive experimental results for a better explanation. This book is meant for scientists and engineers who work in this new OLED framework. It also has didactic utility for graduation students and teachers working on optoelectronics.

• Author : Joseph Shinar
• Publisher :Unknown
• Release Date :2013-03-20
• Total pages :309
• ISBN : 0387217207

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Summary : Although it has long been possible to make organic materials emit light, it has only recently become possible to do so at the level and with the efficiency and control necessary to make the materials a useful basis for illumination in any but the most specialized uses. This book surveys the current status of the field.

• Author : Hartmut Yersin
• Publisher :Unknown
• Release Date :2008-06-25
• Total pages :458
• ISBN : 3527621318

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Summary : This monograph on organic light emitting diodes, edited by a pioneer, and written by front-line researchers from academia and industry, provides access to the latest findings in this rapidly growing field. More than ten contributions cover all areas -- from theory and basic principles, to different emitter materials and applications in production.

• Author : Daniel J. Gaspar,Evgueni Polikarpov
• Publisher :Unknown
• Release Date :2015-05-15
• Total pages :494
• ISBN : 1466515198

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Summary : A Comprehensive Source for Taking on the Next Stage of OLED R&D OLED Fundamentals: Materials, Devices, and Processing of Organic Light-Emitting Diodes brings together key topics across the field of organic light-emitting diodes (OLEDs), from fundamental chemistry and physics to practical materials science and engineering aspects to design and manufacturing factors. Experts from top academic institutions, industry, and national laboratories provide thorough, up-to-date coverage on the most useful materials, devices, and design and fabrication methods for high-efficiency lighting. The first part of the book covers all the construction materials of OLED devices, from substrate to encapsulation. For the first time in book form, the second part addresses challenges in devices and processing, including architectures and methods for new OLED lighting and display technologies. The book is suitable for a broad audience, including materials scientists, device physicists, synthetic chemists, and electrical engineers. It can also serve as an introduction for graduate students interested in applied aspects of photophysics and electrochemistry in organic thin films.

• Author : Feng Gao
• Publisher :Unknown
• Release Date :2019-04-15
• Total pages :500
• ISBN : 0128136472

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Summary : Advanced Nanomaterials for Solar Cells and Light Emitting Diodes discusses the importance of nanomaterials as the active layers in solar cells and light emitting diodes (LEDs), along with the progress of nanomaterials as the electron and hole transporting layers. Specifically, the book reviews the use of nano-morphology of polymers, small molecules, and the organic-inorganic perovskites as the active layers in solar cells and LEDs. The design, fabrication and properties of metal-oxide-based nano-structures as electron and hole transporting layers are also reviewed. In addition, the development of plasmonic nanomaterials for solar cells and LEDs is discussed. Each topic in this book includes an overview of the materials system from principles to process. The advantages, disadvantages and related methodologies are highlighted. The book includes applications based on materials and emphasize how to improve the performance of solar cells and LEDs by the materials design, with a focus on nanomaterials. Provides latest research on nanostructured materials including small molecules, polymers, organic-inorganic perovskites, and many other relevant materials systems for solar cells and LEDs Addresses each promising materials system from principles to process, detailing the advantages and disadvantages of the most relevant methods of processing and fabrication Looks ahead to most likely techniques to improve performance of solar cells and light emitting diodes

• Author : Eli Zysman-Colman
• Publisher :Unknown
• Release Date :2017-03-07
• Total pages :736
• ISBN : 1119007151

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Summary : The fundamental photophysical properties of iridium(III) materials make this class of materials the pre-eminent transition metal complex for use in optoelectronic applications. Iridium(III) in Optoelectronic and Photonics Applications represents the definitive account of photoactive iridium complexes and their use across a wide variety of applications. This two-volume set begins with an overview of the synthesis of these complexes and discusses their photophysical properties. The text highlights not only mononuclear complexes but also the properties of multinuclear and polymeric iridium-based materials and the assembly of iridium complexes into larger supramolecular architectures such as MOFs and soft materials. Chapters devoted to the use of these iridium-based materials in diverse optoelectronic applications follow, including: electroluminescent devices such as organic light emitting diodes (OLEDs) and light-emitting electrochemical cells (LEECs); electrochemiluminescence (ECL); bioimaging; sensing; light harvesting in the context of solar cell applications; in photoredox catalysis and as components for solar fuels. Although primarily targeting a chemistry audience, the wide applicability of these compounds transcends traditional disciplines, making this text also of use to physicists, materials scientists or biologists who have interests in these areas.

• Author : Rubén D. Costa
• Publisher :Unknown
• Release Date :2017-07-31
• Total pages :371
• ISBN : 3319586130

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Summary : This book presents the recent achievements towards the next generation of Light-emitting electrochemical cells (LEC). Its first part focus on the definition, history and mechanism of LEC, going then to concepts and challenges and, finally, giving the reader examples of current application of new electroluminescent materials. The chapters are written by different international groups working on LEC.

• Author : Adrian Kitai
• Publisher :Unknown
• Release Date :2017-03-06
• Total pages :384
• ISBN : 1119140587

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Summary : Cover -- Title Page -- Copyright -- Contents -- List of Contributors -- Series Preface -- Preface -- Acknowledgments -- About the Editor -- Chapter 1 Principles of Solid State Luminescence -- 1.1 Introduction to Radiation from an Accelerating Charge -- 1.2 Radiation from an Oscillating Dipole -- 1.3 Quantum Description of an Electron during a Radiation Event -- 1.4 The Exciton -- 1.5 Two-Electron Atoms -- 1.6 Molecular Excitons -- 1.7 Band-to-Band Transitions -- 1.8 Photometric Units -- 1.9 The Light Emitting Diode -- References -- Chapter 2 Quantum Dots for Displays and Solid State Lighting -- 2.1 Introduction -- 2.2 Nanostructured Materials -- 2.3 Quantum Dots -- 2.3.1 History of Quantum Dots -- 2.3.2 Structure and Properties Relationship -- 2.3.3 Quantum Confinement Effects on Band Gap -- 2.4 Relaxation Process of Excitons -- 2.4.1 Radiative Relaxation -- 2.4.2 Nonradiative Relaxation Process -- 2.5 Blinking Effect -- 2.6 Surface Passivation -- 2.6.1 Organically Capped QDs -- 2.6.2 Inorganically Passivated QDs -- 2.7 Synthesis Processes -- 2.7.1 Top-Down Synthesis -- 2.7.2 Bottom-Up Approach -- 2.8 Optical Properties and Applications -- 2.8.1 Displays -- 2.8.2 Solid State Lighting -- 2.8.3 Biological Applications -- 2.9 Perspective -- Acknowledgments -- References -- Chapter 3 Color Conversion Phosphors for Light Emitting Diodes -- 3.1 Introduction -- 3.2 Disadvantages of Using LEDs Without Color Conversion Phosphors -- 3.3 Phosphors for Converting the Color of Light Emitted by LEDs -- 3.3.1 General Considerations -- 3.3.2 Requirements of Color Conversion Phosphors -- 3.3.3 Commonly Used Activators in Color Conversion Phosphors -- 3.3.4 Strategies for Generating White Light from LEDs -- 3.3.5 Outstanding Problems with Color Conversion Phosphors for LEDs

• Author : Morteza Sasani Ghamsari
• Publisher :Unknown
• Release Date :2017-10-25
• Total pages :170
• ISBN : 9535135759

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Summary : Quantum dot-based light emitting diodes were assigned to bringing together the latest and most important progresses in light emitting diode (LED) technologies. In addition, they were dedicated to gain the perspective of LED technology for all of its advancements and innovations due to the employment of semiconductor nanocrystals. Highly selective, the primary aim was to provide a visual source for high-urgency work that will define the future directions relating to the organic light emitting diode (OLED), with the expectation for lasting scientific and technological impact. The editor hopes that the chapters verify the realization of the mentioned aims that have been considered for editing of this book. Due to the rapidly growing OLED technology, we wish this book to be useful for any progress that can be achieved in future.

• Author : Vardeny Zeev Valy,Wohlgenannt Markus
• Publisher :Unknown
• Release Date :2012-08-23
• Total pages :1368
• ISBN : 9813230169

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Summary : "This series summarizes the field of Organic Spintronics up to 2017. It contains four volumes dedicated to spin injection, spin transport, spin pumping, organic magnetic field effect, and molecular spintronics. The field of Organic Spintronics has accelerated and matured in the last dozen years with the realization of an organic spin-valve (in 2004) and magneto-resistance and magneto-electroluminescence in organic optoelectronic devices (2006). The book series is comprehensive in that it summarizes all aspects of Organic Spintronics to date. The first two volumes deal with spin injection, spin transport, spin manipulation and spin pumping into organic semiconductors. The main device that is thoroughly discussed here is the organic spin-valve, where spinterface states at the interface between the organic semiconductor and the ferromagnetic (FM) electrode has been the focus of many chapters. An interesting emerging subject is the role of chirality in the organic layer of the device. A relatively new method of achieving spin aligned carriers in organic semiconductors is spin pumping, where magnons in the FM substrate generate spin aligned carriers in the organic layer at the FM/organic interface. The third volume deals mainly with magnetic field effect in organic devices. Several spin-mixture processes that lead to magnetic field effect in devices and films are thoroughly discussed, such as hyperfine interaction, direct spin-orbit coupling, indirect spin-orbit coupling via [delta]g, triplet-triplet annihilation, and thermal spin alignment. The similarity between the magnetic field effect obtained in optoelectronic devices based on organic semiconductors and the novel hybrid organic-inorganic semiconductors is also a subject of intense interest. The fourth volume deals with spin in molecular films and devices. It includes thorough discussion of spin exchange interaction that leads to organic ferromagnets, as well as manifestation of various spin interactions in thin molecular films and devices."--

• Author : Anonim
• Publisher :Unknown
• Release Date :2018
• Total pages :229
• ISBN : 09876543XX

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Summary : Abstract : Three highly efficient blue thermally activated delayed fluorescence (TADF) emitters have been synthesized based on pyrimidine, 2-methylpyrimidine and 2-phenylpyrimidine as the acceptor and 10 H -spiro[acridan-9, 9′-fluorene] as the donor moiety. Abstract : Three highly efficient blue thermally activated delayed fluorescence (TADF) emitters, 2SPAc-HPM, 2SPAc-MPM and2SPAc-PPM, have been synthesised based on pyrimidine (PM), 2-methylpyrimidine (MPM) and 2-phenylpyrimidine (PPM) as the acceptor and 10 H -spiro[acridan-9, 9′-fluorene] (2SPAc) as the donor moiety. With their appropriate molecular design, these emitters successfully achieve small singlet–triplet splitting energies for efficient reverse intersystem crossing, and exhibit high photoluminescence quantum yields. As a result, TADF OLEDs based on2SPAc-HPM, 2SPAc-MPM and2SPAc-PPM emit blue light peaking at 479–489 nm and generate very high external quantum efficiencies of 25.56%, 24.34% and 31.45%, respectively. The2SPAc-PPM -based TADF OLED is also one of the very few blue TADF emitters with an external quantum efficiency of more than 30%, and it has the best OLED performance among the pyrimidine-based TADF emitters.