Milestone Developments and New Perspectives of Nano/Nanocrystal Light Emitting Diodes (original) (raw)

Performance Enhancement and Applications Review of Nano Light Emitting Device (LED)

Nanomaterials, 2020

A nano light emitting device (LED) has been developed and is presented. This new LED, entitled LENS (Light Emitting Nano-pixel Structure), is a new nano-pixel structure designed to enable high-resolution display. It serves as the building block of a more complex structure called LENA (Light Emitting Nano-pixel Array), dedicated to nano-display applications, such as augmented and virtual reality (AVR). Previously designed and studied with a platform for ray tracing optimization, a complementary simulations study was performed using the Comsol Multi-Physics Platform in order to check for opto-electronics performance and physical nanoscale investigations. In addition to the physical complementary analysis, several studies have focused on optimizations: optimal geometry for a pixel (cylindrical or conical shape), and wavelength adaptation (optical communication). In addition to numerical simulation results, an analytical model has been developed. This new device holds the potential to e...

White-light-emitting diodes using semiconductor nanocrystals

Mikrochimica Acta, 2007

Light-emitting diodes (LEDs) based on colloidal inorganic semiconductor nanocrystals (QDs) represent a completely new technology platform for the development of flat-panel displays and flat-panel lighting systems. Their major advantages are the easy tuning of the saturated color emission across the visible-NIR range and the high chemical and optical stability of the nanocrystal composites. These characteristics open the way to a new class of hybrid devices in which the low cost, flexible technology of organic LEDs is combined with the long operating lifetime of inorganic semiconductor devices. However, so far, few studies have been reported on white-LEDs based on QDs. This review shows recent developments in the general method for the fabrication of stable white-LEDs comprising QDs with a potentially long lifetime.

Engineering of Semiconductor Nanocrystals for Light Emitting Applications

Materials, 2016

Semiconductor nanocrystals are rapidly spreading into the display and lighting markets. Compared with liquid crystal and organic LED displays, nanocrystalline quantum dots (QDs) provide highly saturated colors, wide color gamut, resolution, rapid response time, optical efficiency, durability and low cost. This remarkable progress has been made possible by the rapid advances in the synthesis of colloidal QDs and by the progress in understanding the intriguing new physics exhibited by these nanoparticles. In this review, we provide support to the idea that suitably engineered core/graded-shell QDs exhibit exceptionally favorable optical properties, photoluminescence and optical gain, while keeping the synthesis facile and producing QDs well suited for light emitting applications. Solid-state laser emitters can greatly profit from QDs as efficient gain materials. Progress towards fabricating low threshold, solution processed DFB lasers that are optically pumped using one-and two-photon absorption is reviewed. In the field of display technologies, the exploitation of the exceptional photoluminescence properties of QDs for LCD backlighting has already advanced to commercial levels. The next big challenge is to develop the electroluminescence properties of QD to a similar state. We present an overview of QLED devices and of the great perspectives for next generation display and lighting technologies.

Light emitting devices based on nanostructured semiconductors

SPIE Proceedings, 2005

Light emitting devices based on high-efficiency photoluminescence (PL) fluorescent nanocrystals have been investigated in terms of the generation of light from the structure using a variety of deposition methods. An automated modified layer-by-layer (LbL) self-assembly technique has been employed to produce multilayers of thiol-capped red fluorescing CdTe nanocrystals. Indium-tin-oxide (ITO) and aluminium electrodes were used as the electrodes. Morphological characterization was carried out through Schottky field effect (SFEG) SEM and atomic force microscopy (AFM). The structures built presented clear red electroluminescence (EL) to the naked eye. Turn on voltages were found to be in the range of 3-6 volts while the onset current was in the order of tens of microamperes. The role of structure homogeneity, the presence of pinholes and lifetime extension were features addressed during this investigation. Samples with a lifetime of continuous operation in air longer than 60 minutes and highly stable EL spectra were achieved; EL was visible to the unaided eye, although the brightness was still below the commercial standards and has not yet been qualified.

Nanotechnology for High-Tech Industries: Light-Emitting Diodes

Science, Technology and Innovation Studies, 2019

Enhancing energy efficiency has been one of the top policy goals in many countries in the last decade. Innovative lighting solutions, and light-emitting diodes (LEDs) in particular, are among the very much promising opportunities to increase energy efficiency. A modern LED is a multilayer thin-film structure with the thickness of layers in the range of nanometers. LED technologies are becoming dominant in a number of application segments. Demand for economic and energy security makes the development of the LED industry one of the national priorities in many countries including Canada, the USA, Japan, and China and European countries, among others.

Color science of nanocrystal quantum dots for lighting and displays

Nanophotonics, 2013

Colloidal nanocrystals of semiconductor quantum dots (QDs) are gaining prominence among the optoelectronic materials in the photonics industry. Among their many applications, their use in artificial lighting and displays has attracted special attention thanks to their high efficiency and narrow emission band, enabling spectral purity and fine tunability. By employing QDs in color-conversion LEDs, it is possible to simultaneously accomplish successful color rendition of the illuminated objects together with a good spectral overlap between the emission spectrum of the device and the sensitivity of the human eye, in addition to a warm white color, in contrast to other conventional sources such as incandescent and fluorescent lamps, and phosphorbased LEDs, which cannot achieve all of these properties at the same time. In this review, we summarize the color science of QDs for lighting and displays, and present the recent developments in QD-integrated LEDs and display research. First, we start with a general introduction to color science, photometry, and radiometry. After presenting an overview of QDs, we continue with the spectral designs of QD-integrated white LEDs that have led to efficient lighting for indoor and outdoor applications. Subsequently, we discuss QD color-conversion LEDs and displays as proof-of-concept applications -a new paradigm in artificial lighting and displays. Finally, we conclude with a summary of research opportunities and challenges along with a future outlook.