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"diodes"
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Diode fibres for fabric-based optical communications
Semiconductor diodes are basic building blocks of modern computation, communications and sensing
1
. As such, incorporating them into textile-grade fibres can increase fabric capabilities and functions
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, to encompass, for example, fabric-based communications or physiological monitoring. However, processing challenges have so far precluded the realization of semiconducting diodes of high quality in thermally drawn fibres. Here we demonstrate a scalable thermal drawing process of electrically connected diode fibres. We begin by constructing a macroscopic preform that hosts discrete diodes internal to the structure alongside hollow channels through which conducting copper or tungsten wires are fed. As the preform is heated and drawn into a fibre, the conducting wires approach the diodes until they make electrical contact, resulting in hundreds of diodes connected in parallel inside a single fibre. Two types of in-fibre device are realized: light-emitting and photodetecting p–i–n diodes. An inter-device spacing smaller than 20 centimetres is achieved, as well as light collimation and focusing by a lens designed in the fibre cladding. Diode fibres maintain performance throughout ten machine-wash cycles, indicating the relevance of this approach to apparel applications. To demonstrate the utility of this approach, a three-megahertz bi-directional optical communication link is established between two fabrics containing receiver–emitter fibres. Finally, heart-rate measurements with the diodes indicate their potential for implementation in all-fabric physiological-status monitoring systems. Our approach provides a path to realizing ever more sophisticated functions in fibres, presenting the prospect of a fibre ‘Moore's law’ analogue through the increase of device density and function in thermally drawn textile-ready fibres.
A scalable thermal drawing process is used to integrate light-emitting and photodetecting diodes into textile-ready polymer fibres, which can be woven into fabrics with possible optical communication and health monitoring applications.
Journal Article
LED packaging for lighting applications
This book is ideal for practicing engineers working in design or packaging at LED companies and graduate students preparing for work in industry. This book also provides a helpful introduction for advanced undergraduates, graduates, researchers, lighting designers, and product managers interested in the fundamentals of LED design and production.
eBook
Planet LED
\"Planet LED is a book filled with bright ideas. LED technology has long been recognized as a revolution in lighting capability and energy efficiency. Since its inception in the 1960's its development has known few boundaries, literally lighting the way of the future. There are pioneers in the field of design-- many of whom are included in this publication-- who explore the possibilities of LED lighting for the world. Through a series of chapters containing exclusive interviews and commentary, multiple aspects of the prospective growth of LED technology are discussed, bringing the viewer into lighting world through exciting and maverick approaches from inception to realization.\" -- Provided by publisher.
Book
Aggregation‐induced emission: Red and near‐infrared organic light‐emitting diodes
Red and near‐infrared (NIR) organic light‐emitting diodes (OLED) have gained remarkable interest due to their numerous applications. However, the construction of highly emissive emitters is hampered by the energy‐gap law and aggregation‐caused quenching (ACQ) effect. Whereas, aggregation‐induced emission (AIE) materials could avoid the undesirable ACQ effect and emit bright light in aggregated state, which is one class of the most promising materials to fabricate high‐performance OLED with a high external quantum efficiency and low efficiency roll‐off. This review summarizes recent advances in red and NIR OLED with AIE property, including the traditional fluorescence, thermally activated delayed fluorescence, and hybridized local and charge transfer compounds. Meanwhile, the emphasis attention is paid to the molecular design principles, as well as the molecular structure‐photophysical characteristics. We also briefly further outlook the challenges and perspective of red and NIR AIE luminogens. In the field of organic light‐emitting diodes (OLED), red and near‐infrared (NIR) emitter with aggregation‐induced emission (AIE) effect can be divided into fluorescence, thermally activated delayed fluorescence (TADF), and hybridized local and charge transfer (HLCT) according to emission mechanism.
Journal Article
Highly efficient and stable InP/ZnSe/ZnS quantum dot light-emitting diodes
Quantum dot (QD) light-emitting diodes (LEDs) are ideal for large-panel displays because of their excellent efficiency, colour purity, reliability and cost-effective fabrication
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–
4
. Intensive efforts have produced red-, green- and blue-emitting QD-LEDs with efficiencies of 20.5 per cent
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, 21.0 per cent
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and 19.8 per cent
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, respectively, but it is still desirable to improve the operating stability of the devices and to replace their toxic cadmium composition with a more environmentally benign alternative. The performance of indium phosphide (InP)-based materials and devices has remained far behind those of their Cd-containing counterparts. Here we present a synthetic method of preparing a uniform InP core and a highly symmetrical core/shell QD with a quantum yield of approximately 100 per cent. In particular, we add hydrofluoric acid to etch out the oxidative InP core surface during the growth of the initial ZnSe shell and then we enable high-temperature ZnSe growth at 340 degrees Celsius. The engineered shell thickness suppresses energy transfer and Auger recombination in order to maintain high luminescence efficiency, and the initial surface ligand is replaced with a shorter one for better charge injection. The optimized InP/ZnSe/ZnS QD-LEDs showed a theoretical maximum external quantum efficiency of 21.4 per cent, a maximum brightness of 100,000 candelas per square metre and an extremely long lifetime of a million hours at 100 candelas per square metre, representing a performance comparable to that of state-of-the-art Cd-containing QD-LEDs. These as-prepared InP-based QD-LEDs could soon be usable in commercial displays.
A method of engineering efficient and stable InP/ZnSe/ZnS quantum dot light-emitting diodes (QD-LEDs) has improved their performance to the level of state-of-the-art cadmium-containing QD-LEDs, removing the problem of the toxicity of cadmium in large-panel displays.
Journal Article
How LEDs work
\"This book will explain how light-emitting diodes (LEDs) work and what products they are used in, as well as comparing LEDs with traditional incandescent and fluorescent light bulbs.\"-- Provided by publisher.
Book
High-performance light-emitting diodes based on carbene-metal-amides
Organic light-emitting diodes (OLEDs) promise highly efficient lighting and display technologies. We introduce a new class of linear donor-bridge-acceptor light-emitting molecules, which enable solution-processed OLEDs with near-100% internal quantum efficiency at high brightness. Key to this performance is their rapid and efficient utilization of triplet states. Using time-resolved spectroscopy, we establish that luminescence via triplets occurs within 350 nanoseconds at ambient temperature, after reverse intersystem crossing to singlets. We find that molecular geometries exist at which the singlet-triplet energy gap (exchange energy) is close to zero, so that rapid interconversion is possible. Calculations indicate that exchange energy is tuned by relative rotation of the donor and acceptor moieties about the bridge. Unlike other systems with low exchange energy, substantial oscillator strength is sustained at the singlet-triplet degeneracy point.
Journal Article