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2017 | Buch

Photoluminescent Materials and Electroluminescent Devices

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Über dieses Buch

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.

Inhaltsverzeichnis

Frontmatter
Luminescent Metal-Containing Polymers for White Light Emission
Abstract
This chapter focuses on the recent developments in luminescent metallopolymers. Synthetic routes to these polymers are briefly described and their applications in polymer white light-emitting diodes are discussed.
Cheuk-Lam Ho, Wai-Yeung Wong
Luminescent Iridium Complexes Used in Light-Emitting Electrochemical Cells (LEECs)
Abstract
Cationic iridium(III) complexes represent the single largest class of emitters used in light emitting electrochemical cells (LEECs). In this chapter, we highlight the state-of-the-art emitters in terms of efficiency and stability in LEEC devices, highlighting blue, green, yellow/orange, red and white devices, and provide an outlook to the future of LEECs.
Adam F. Henwood, Eli Zysman-Colman
Platinum and Gold Complexes for OLEDs
Abstract
Encouraging efforts on the design of high-performance organic materials and smart architecture during the past two decades have made organic light-emitting device (OLED) technology an important competitor for the existing liquid crystal displays. Particularly, the development of phosphorescent materials based on transition metals plays a crucial role for this success. Apart from the extensively studied iridium(III) complexes with d6 electronic configuration and octahedral geometry, the coordination-unsaturated nature of d8 transition metal complexes with square-planar structures has been found to provide intriguing spectroscopic and luminescence properties. This article briefly summarizes the development of d8 platinum(II) and gold(III) complexes and their application studies in the fabrication of phosphorescent OLEDs. An in-depth understanding of the nature of the excited states has offered a great opportunity to fine-tune the emission colors covering the entire visible spectrum as well as to improve their photophysical properties. With good device engineering, high performance vacuum-deposited OLEDs with external quantum efficiencies (EQEs) of up to 30 % and solution-processable OLEDs with EQEs of up to 10 % have been realized by modifying the cyclometalated or pincer ligands of these metal complexes. These impressive demonstrations reveal that d8 metal complexes are promising candidates as phosphorescent materials for OLED applications in displays as well as in solid-state lighting in the future.
Man-Chung Tang, Alan Kwun-Wa Chan, Mei-Yee Chan, Vivian Wing-Wah Yam
Phosphorescent Neutral Iridium (III) Complexes for Organic Light-Emitting Diodes
Abstract
The development of transition metal complexes for application in lightemitting devices is currently attracting significant research interest. Among phosphorescent emitters, those involving iridium (III) complexes have proven to be exceedingly useful due to their relatively short triplet lifetime and high phosphorescence quantum yields. The emission wavelength of iridium (III) complexes significantly depends on the ligands, and changing the electronic nature and the position of the ligand substituents can control the properties of the ligands. In this chapter, we discuss recent developments of phosphorescent transition metal complexes for organic light-emitting diode applications focusing solely on the development of iridium metal complexes.
Abd. Rashid Bin Mohd Yusoff, Aron J. Huckaba, Mohammad Khaja Nazeeruddin
Copper(I) Complexes for Thermally Activated Delayed Fluorescence: From Photophysical to Device Properties
Abstract
Molecules that exhibit thermally activated delayed fluorescence (TADF) represent a very promising emitter class for application in electroluminescent devices since all electrically generated excitons can be transferred into light according to the singlet harvesting mechanism. Cu(I) compounds are an important class of TADF emitters. In this contribution, we want to give a deeper insight into the photophysical properties of this material class and demonstrate how the emission properties depend on molecular and host rigidity. Moreover, we show that with molecular optimization a significant improvement of selected emission properties can be achieved. From the discussed materials, we select one specific dinuclear complex, for which the two Cu(I) centers are four-fold bridged to fabricate an organic light emitting diode (OLED). This device shows the highest efficiency (of 23 % external quantum efficiency) reported so far for OLEDs based on Cu(I) emitters.
Markus J. Leitl, Daniel M. Zink, Alexander Schinabeck, Thomas Baumann, Daniel Volz, Hartmut Yersin
Materials Integrating Photochemical Upconversion
Abstract
This review features recent experimental work focused on the preparation and characterization of materials that integrate photochemical upconversion derived from sensitized triplet–triplet annihilation, resulting in the conversion of low energy photons to higher energy light, thereby enabling numerous wavelengthshifting applications. Recent topical developments in upconversion include encapsulating or rigidifying fluid solutions to give them mechanical strength, adapting inert host materials to enable upconversion, and using photoactive materials that incorporate the sensitizer and/or the acceptor. The driving force behind translating photochemical upconversion from solution into hard and soft materials is the incorporation of upconversion into devices and other applications. At present, some of the most promising applications of upconversion materials include imaging and fluorescence microscopy, photoelectrochemical devices, water disinfection, and solar cell enhancement.
Catherine E. McCusker, Felix N. Castellano
Metal–Organic and Organic TADF-Materials: Status, Challenges and Characterization
Abstract
This section covers both metal–organic and organic materials that feature thermally activated delayed fluorescence (TADF). Such materials are especially useful for organic light-emitting diodes (OLEDs), a technology that was introduced in commercial displays only recently. We compare both material classes to show commonalities and differences, highlighting current issues and challenges. Advanced spectroscopic techniques as valuable tools to develop solutions to those issues are introduced. Finally, we provide an outlook over the field and highlight future trends.
Larissa Bergmann, Daniel M. Zink, Stefan Bräse, Thomas Baumann, Daniel Volz
Perovskite Luminescent Materials
Abstract
We describe recent progress on the luminescent properties of hybrid organic inorganic metal halide perovskites and the LEDs employing them.
Michele Sessolo, Lidón Gil-Escrig, Giulia Longo, Henk J. Bolink
The Rise of Near-Infrared Emitters: Organic Dyes, Porphyrinoids, and Transition Metal Complexes
Abstract
In recent years, the interest in near-infrared (NIR) emitting molecules and materials has increased significantly, thanks to the expansion of the potential technological applications of NIR luminescence in several areas such as bioimaging, sensors, telecommunications, and night-vision displays. This progress has been facilitated by the development of new synthetic routes for the targeted functionalization and expansion of established molecular frameworks and by the availability of simpler and cheaper NIR detectors. Herein, we present recent developments on three major classes of systems—i.e., organic dyes, porphyrinoids, and transition metal complexes—exhibiting the maximum of the emission band at λ > 700 nm. In particular, we focus on the design strategies that may increase the luminescence efficiency, while pushing the emission band more deeply in the NIR region. This overview suggests that further progress can be achieved in the near future, with enhanced availability of more robust, stronger, and cheaper NIR luminophores.
Andrea Barbieri, Elisa Bandini, Filippo Monti, Vakayil K. Praveen, Nicola Armaroli
Inorganic Phosphor Materials for Lighting
Abstract
This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structure– property relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.
Yuan-Chih Lin, Maths Karlsson, Marco Bettinelli
Organic Light-Emitting Devices with Tandem Structure
Abstract
Tandem organic light-emitting devices (OLEDs) have attracted considerable attention for solid-state lighting and flat panel displays because their tandem architecture enables high efficiency and long operational lifetime simultaneously. In the tandem OLED structure, plural light-emitting units (LEUs) are stacked in series through a charge generation layer (CGL) and an electron injection layer (EIL). In this chapter, we focus on the key features of tandem OLEDs for high efficiency and long operational lifetimes. We also demonstrate the effect of the CGL comprising a Lewis acid, an n-type semiconductor metal oxide, and an organic electron-accepting material. We discuss the two types of EILs in tandem OLEDs: alkali metals containing n-type compounds and ultra-thin metals. Finally, we focus on the recent progress of the state-of-the-art solution-processed tandem OLEDs.
Takayuki Chiba, Yong-Jin Pu, Junji Kido
Light-Emitting Electrochemical Cells: A Review on Recent Progress
Abstract
The light-emitting electrochemical cell (LEC) is an area-emitting device, which features a complex turn-on process that ends with the formation of a p-n junction doping structure within the active material. This in-situ doping transformation is attractive in that it promises to pave the way for an unprecedented lowcost fabrication of thin and light-weight devices that present efficient light emission at low applied voltage. In this review, we present recent insights regarding the operational mechanism, breakthroughs in the development of scalable and adaptable solution-based methods for cost-efficient fabrication, and successful efforts toward the realization of LEC devices with improved efficiency and stability.
Shi Tang, Ludvig Edman
Metadaten
Titel
Photoluminescent Materials and Electroluminescent Devices
herausgegeben von
Nicola Armaroli
Henk J. Bolink
Copyright-Jahr
2017
Electronic ISBN
978-3-319-59304-3
Print ISBN
978-3-319-59302-9
DOI
https://doi.org/10.1007/978-3-319-59304-3

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