12CaO.7Al2O3 ceramic: A review of the electronic and optoelectronic applications in display devices

The alumina-based compound, 12CaO.7Al2O3, is a ceramic material with a unique cage-like lattice. Such a structure has enabled scientists to extract various new characteristics from this compound, most of which were unknown until quite recently. This compound has the ability to incorporate different anionic species and even electrons to the empty space inside its cages, thereby changing from an insulator into a conductive oxide. The cage walls can also incorporate different rare earth phosphor elements producing an oxide-based phosphor. All these characteristics are obtained without a significant change in the structure of the lattice. It is, therefore, reasonable to expect that this compound will receive attention as a potential material for display applications. This review article presents recent investigations into the application of 12CaO.7Al2O3 ceramic in various display devices, the challenges, opportunities and possible areas of future investigation into the development of this naturally abundant and environmental friendly material in the field of display.LP Displays Ltd, Blackburn, UK for partial funding of the studentship at Queen Mary, University of London. Dr Lesley Hanna of Wolfson Centre for Materials Processing, Brunel University Londo

Luminescence in sulfides : a rich history and a bright future

Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials) to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs). The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles

POLYMERS AND ITS APPLICATION IN LIGHT EMITTING DIODES: A REVIEW ARTICLE

Polymers are widely used in electrical and electronic applications and also play a very important role in human life. Our body is made of lot of polymers, like Proteins, enzymes, etc. They are substances whose molecules have high molar masses and are composed of a large number of repeating units. Other naturally occurring polymers like wood, rubber, leather and silk are serving the humankind for many centuries now. Today’s development of polymeric electroluminescent diodes for flat panel displays offers many advantages, including their versatility for fabrication, flexibility, low operating voltage, and the ease with which color tuning of light emission can be achieved. It has different applications such as antistatic coating of polymers and glass, high conductive shell, organic light emitting diode displays, nano-fiber electrodes for unit stimulation, solar cells, cathode material in electrolytic capacitors, printing wiring panels, textile fibers with colour varying properties, transparent electrodes for thick-film electroluminescence, source gate and drain in the quickly developing organic semi-conductors field. One of the applications of polymer is to use in the fabrication of light emitting diodes and the one which is produced from the organic polymer is more advantageous over the inorganic one. Key words: light emitting diode, polymers, organic light emitting diode

Quantum Dot-Based Light Emitting Diodes (QDLEDs): New Progress

In recent years, the display industry has progressed rapidly. One of the most important developments is the ability to build flexible, transparent and very thin displays by organic light emitting diode (OLED). Researchers working on this field try to improve this area more and more. It is shown that quantum dot (QD) can be helpful in this approach. In this chapter, writers try to consider all the studies performed in recent years about quantum dot-based light emitting diodes (QDLEDs) and conclude how this nanoparticle can improve performance of QDLEDs. In fact, the existence of quantum dots in QDLEDs can cause an excellent improvement in their efficiency and lifetime resulted from using improved active layer by colloidal nanocrystals. Finally, the recent progresses on the quantum dot-based light emitting diodes are reviewed in this chapter, and an important outlook into challenges ahead is prepared

Chemical Degradation of OLED Host Materials: The Role of Non-Local Interaction in Electronic Excited States

Department of PhysicsOrganic light-emitting devices (OLEDs) have been attracted to both academia and industry, because of their wide applications and remarkable advances in display. Despite the conspicuous advances in OLEDs and even their successful implementation in commercial displays, device degradation issues still remain as one of the most important problems. Because degradation occurs mostly in operating conditions, the underlying mechanism is considered to be linked to carriers in excited states. While several theoretical and experimental studies have focused on the mechanisms of OLED degradation, the microscopic role of the excited carrier remains elusive. In this work, I study how chemical degradation is driven by the excited carrier in OLED materials, using occupation-constrained density functional theory calculations. The results show that the C-N bond is a weak link of OLED molecules both in the electronic ground and excited states, and the rupture of the bond is the main cause of the chemical degradation in short lifetime. While the excited carrier generally weakens the bond, the effect can be mitigated by the non-local interaction with the other bonding and anti-bonding states. The results suggest that the presence of such a non-local interaction can contribute to an enhancement of the chemical stability of the materials in operating environments.ope

Roadmap on perovskite light-emitting diodes

In recent years, the field of metal-halide perovskite emitters has rapidly emerged as a new community in solid-state lighting. Their exceptional optoelectronic properties have contributed to the rapid rise in external quantum efficiencies (EQEs) in perovskite light-emitting diodes (PeLEDs) from <1% (in 2014) to over 30% (in 2023) across a wide range of wavelengths. However, several challenges still hinder their commercialization, including the relatively low EQEs of blue/white devices, limited EQEs in large-area devices, poor device stability, as well as the toxicity of the easily accessible lead components and the solvents used in the synthesis and processing of PeLEDs. This roadmap addresses the current and future challenges in PeLEDs across fundamental and applied research areas, by sharing the community’s perspectives. This work will provide the field with practical guidelines to advance PeLED development and facilitate more rapid commercialization

Nanomaterial integration in micro LED technology: Enhancing efficiency and applications

The micro-light emitting diode (µLED) technology is poised to revolutionise display applications through the introduction of nanomaterials and Group III-nitride nanostructures. This review charts state-of-the-art in this important area of micro-LEDs by highlighting their key roles, progress and concerns. The review encompasses details from various types of nanomaterials to the complexity of gallium nitride (GaN) and III nitride nanostructures. The necessity to integrate nanomaterials with III-nitride structures to create effective displays that could disrupt industries was emphasised in this review. Commercialisation challenges and the economic enhancement of micro-LED integration into display applications using monolithic integrated devices have also been discussed. Furthermore, different approaches in micro-LED development are discussed from top-down and bottom-up approaches. The last part of the review focuses on nanomaterials employed in the production of micro-LED displays. It also highlights the combination of III-V LEDs with silicon LCDs and perovskite-based micro-LED displays. There is evidence that efficiency and performance have improved significantly since the inception of the use of nanomaterials in manufacturing these