Ever since the first cadmium selenide quantum dot-based light-emitting devices (QLEDs) were reported in 1994, the dominant materials for QLEDs investigated since then have been limited to wurtzite or zinc blende Cd-based QDs. Similarly, the best developed and studied colloidal QD lasers have been fabricated from Cd-based semiconductors. Now, researchers have presented a new family of photoelectric materials for light-emitting devices: colloidal all-inorganic perovskite cesium lead halide QDs. This new material could find applications in LEDs and lasers, and has an especially big potential in high-performance displays, lighting, monochromatic narrow-band photodetectors, and optical communications.
Colloidal quantum dot nanocrystals are attractive materials for optoelectronics, sensing devices and third generation photovoltaics. Researchers have now developed an automated, scalable, in-line synthesis methodology of high-quality colloidal quantum dots based on a flow-reactor with two temperature-stages of narrow channel coils. The flow-reactor methodology not only enables easy scalability and cheap production, but also affords rapid screening of parameters, automation, and low reagent consumption during optimization.
Using quantum dots as the basis for solar cells is not a new idea, but attempts to make such devices have not yet achieved sufficiently high efficiency in converting sunlight to power. Although these performance levels are promising, all high-performing device results to date have relied on a multiple-layer-by-layer strategy for film fabrication rather than employing a single-layer deposition process. Now, though, researchers have developed a semiconductor ink with the goal of enabling the coating of large areas of solar cell substrates in a single deposition step and thereby eliminating tens of deposition steps necessary with the previous layer-by-layer method.
Quantum dots are expected to deliver lower cost, higher energy efficiency and greater wavelength control for a wide range of products, including lamps, displays and photovoltaics. Unfortunately, the toxicity of the elements used for efficient quantum dot based LEDs is a severe drawback for many applications. Therefore, light-emitting devices which are based on the non-toxic element silicon are extraordinary promising candidates for future QD-lighting applications. Researchers have now demonstrated highly efficient and widely color-tunable silicon light-emitting diodes (SiLEDs). The emission wavelength of the devices can easily be tuned from the deep red (680 nm) down to the orange/yellow (625 nm) spectral region by simply changing the size of the used size-separated silicon nanocrystals.
Knowing the distribution of DNA binding proteins along the genome is very informative and can tell scientists about the state of gene expression at the time of measurement. These DNA-binding proteins include transcription factors which modulate the process of transcription, various polymerases, nucleases which cleave DNA molecules, and histones which are involved in chromosome packaging in the cell nucleus. Previously, researchers demonstrated the viability of a single-molecule approach to directly visualize and map protein binding sites on DNA using fluorescent quantum dots, allowing multicolor, nanometer-resolution localization. Now, they have shown that proteins bound to DNA can be located very accurately by direct imaging. The precision of these measurement presents new opportunities for contextual genomic research on the single-molecule level.
In January 2007, China successfully tested an Anti-satellite (ASAT) missile system by destroying their own defunct LEO satellite, which generated huge amounts of space debris. This ASAT test raised worldwide concerns about the vulnerability of satellites and other space assets and possibility of triggering an arms race in space. In order to meet emerging challenges posed by such ASAT missile systems, military strategists and researchers are developing novel technologies to protect their space assets. In view of the above, Raytheon Company has developed a counter measure system using quantum dots to protect space assets such as satellites from missile attacks. They have developed a decoy consisting of quantum dots of different sizes and shapes that are engineered to emit radiation having a radiation profile similar to that of the asset.
A University of Ulster laboratory has found a simple, low cost and environmentally friendly way to turn common graphite flakes into bulk amounts of either high quality graphene nanosheets or quantum dots. Such structures could lead to new nanoelectronics and energy conversion technologies. The scientists discovered a simple process, which is quicker and environmentally friendlier than currently established techniques for making high quality graphene nanosheets and quantum dots at an industrial scale. The most important attribute of the produced graphene nanosheets and quantum dots compared to those reported in the literature is that they are clean from any solvent contamination and possess a low concentration of oxygen, which is inherited from the starting graphite powder.
Quantum dots, because they are both photoluminescent and electroluminescent and have unique physical properties, will be at the core of next-generation displays. Compared to organic luminescent materials used in organic light emitting diodes (OLEDs), QD-based materials have purer colors, longer lifetime, lower manufacturing cost, and lower power consumption. Another key advantage is that, because QDs can be deposited on virtually any substrate, you can expect printable and flexible displays of all sizes. To date, the integration of QDs into a full-color LED structure has not been possible due to the difficulty in patterning individual red-green-blue (RGB) QDs onto the pixelated display panel. Now, a Samsung team has demonstrated a novel transfer printing approach which enables fine patterning of high-quality QD films for large-area (4-inch diagonal), full-color displays mounted on glass as well as on flexible plastic substrates.