Electrical and Electronic Engineering - Research Publications
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ItemNo Preview AvailableLow‐Temperature Solution‐Processed Transparent QLED Using Inorganic Metal Oxide Carrier Transport Layers (Adv. Funct. Mater. 3/2022)(Wiley, 2022-01)In article number 2106387, Yang Yu, Efstratios Skafidas, and co-workers present transparent and fully solution processed inorganic quantum dots LED (QLED). To improve upon the structures hole injection efficiency, a low-temperature sol-gel derived copper doped NiO interlayer is introduced. The derived QLED analytical models and simulation results are in good concordance with experimental results, providing a new framework for the development of novel QLEDs.
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ItemA Silk Fibroin Bio-Transient Solution Processable Memristor(NATURE PORTFOLIO, 2017-11-07)Today's electronic devices are fabricated using highly toxic materials and processes which limits their applications in environmental sensing applications and mandates complex encapsulation methods in biological and medical applications. This paper proposes a fully resorbable high density bio-compatible and environmentally friendly solution processable memristive crossbar arrays using silk fibroin protein which demonstrated bipolar resistive switching ratio of 104 and possesses programmable device lifetime characteristics before the device gracefully bio-degrades, minimizing impact to environment or to the implanted host. Lactate dehydrogenase assays revealed no cytotoxicity on direct exposure to the fabricated device and support their environmentally friendly and biocompatible claims. Moreover, the correlation between the oxidation state of the cations and their tendency in forming conductive filaments with respect to different active electrode materials has been investigated. The experimental results and the numerical model based on electro-thermal effect shows a tight correspondence in predicting the memristive switching process with various combinations of electrodes which provides insight into the morphological changes of conductive filaments in the silk fibroin films.
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ItemLow-Temperature Solution-Processed Transparent QLED Using Inorganic Metal Oxide Carrier Transport Layers(WILEY-V C H VERLAG GMBH, 2022-01)Abstract Quantum dot light‐emitting diodes (QLEDs) represent an exciting new technology that has many desirable attributes when compared to existing organic LEDs (OLEDs) including increased brightness, contrast, and response time. Solution‐based fabrication approaches have the advantage of being able to produce large‐area electronic systems at reduced costs and critical in applications such as large display fabrication and electronics on curved surfaces including low‐profile augmented reality glasses. In this paper, for the first time, a fully solution‐processed transparent inorganic QLED is described. Traditional QLED fabrication methodologies require the use of air‐sensitive materials that make fabrication of these devices challenging and expensive. Instead of using air‐sensitive organic materials, in the approach, nickel oxide (NiO) is used as the hole transport layer and is deposited using a sol‐gel method. Copper doping of the NiO to reduce the turn‐on voltage of the QLED device is investigated. Importantly, the post‐annealing temperature of the sol‐gel process is below 275 °C, which permits the fabrication of QLEDs on a wide range of substrates. The experimental results are concordant with the COMSOL simulation data and demonstrate the feasibility of fabricating fully transparent inorganic QLED devices using a solution‐based process.
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ItemA single sensor based multispectral imaging camera using a narrow spectral band color mosaic integrated on the monochrome CMOS image sensor(AIP Publishing LLC, 2020-04-01)A multispectral image camera captures image data within specific wavelength ranges in narrow wavelength bands across the electromagnetic spectrum. Images from a multispectral camera can extract a additional information that the human eye or a normal camera fails to capture and thus may have important applications in precision agriculture, forestry, medicine, and object identification. Conventional multispectral cameras are made up of multiple image sensors each fitted with a narrow passband wavelength filter and optics, which makes them heavy, bulky, power hungry, and very expensive. The multiple optics also create an image co-registration problem. Here, we demonstrate a single sensor based three band multispectral camera using a narrow spectral band red–green–blue color mosaic in a Bayer pattern integrated on a monochrome CMOS sensor. The narrow band color mosaic is made of a hybrid combination of plasmonic color filters and a heterostructured dielectric multilayer. The demonstrated camera technology has reduced cost, weight, size, and power by almost n times (where n is the number of bands) compared to a conventional multispectral camera.
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ItemFilling schemes at submicron scale: Development of submicron sized plasmonic colour filters(NATURE PORTFOLIO, 2014-09-22)The pixel size imposes a fundamental limit on the amount of information that can be displayed or recorded on a sensor. Thus, there is strong motivation to reduce the pixel size down to the nanometre scale. Nanometre colour pixels cannot be fabricated by simply downscaling current pixels due to colour cross talk and diffraction caused by dyes or pigments used as colour filters. Colour filters based on plasmonic effects can overcome these difficulties. Although different plasmonic colour filters have been demonstrated at the micron scale, there have been no attempts so far to reduce the filter size to the submicron scale. Here, we present for the first time a submicron plasmonic colour filter design together with a new challenge - pixel boundary errors at the submicron scale. We present simple but powerful filling schemes to produce submicron colour filters, which are free from pixel boundary errors and colour cross- talk, are polarization independent and angle insensitive, and based on LCD compatible aluminium technology. These results lay the basis for the development of submicron pixels in displays, RGB-spatial light modulators, liquid crystal over silicon, Google glasses and pico-projectors.