Quantum Dots - Page 2

Ulsan National Institute of Science and Technology (UNIST) researchers have developed solar cells using narrow bandgap organic cation-based perovskite-based quantum dots (PQDs) and demonstrated substantially higher efficiency compared with their inorganic counterparts. 

The team stressed that research to this point has predominantly focused on inorganic cation PQDs despite the fact that organic cation PQDs have more favorable bandgaps. However, the recent study unveiled a novel ligand exchange technique, that enables the synthesis of organic cation-based PQDs, ensuring exceptional stability while suppressing internal defects in the photoactive layer of solar cells.

A team of researchers, led by Maksym Kovalenko at ETH Zurich and Empa, working in collaboration with scientists from the U.S. and Ukraine, recently demonstrated how the promising properties of perovskite quantum dots can be improved further. They used chemical methods for surface treatment and quantum mechanical effects that had never before been observed in perovskite quantum dots. 

Perovskite quantum dots can be mixed with liquids to form a dispersion, which makes them easy to process. Moreover, their special optical properties make them shine more brightly than many other quantum dots. They can also be produced more cheaply, which makes them interesting for applications in displays, for instance. On top of all this, the newly developed phospholipid molecules create a protective layer around the perovskite nanocrystal and make it possible to disperse it in non-aqueous solutions. They also ensure that the quantum dot emits photons more continuously. 

Swiss additive manufacturing startup Scrona and Avantama, developer and manufacturer of high-tech materials for electronics, have jointly announced that they have successfully processed high-performance perovskite quantum dot (QD) ink using Scrona's electrohydrodynamic (EHD) inkjet printing. 

This collaboration combines the benefits of the inkjet process with high-patterning resolution to drive a new generation of efficient and cost effective MicroLED displays, while also increasing color purity and brightness, and improving overall pixel production tact time. 

Researchers at Pusan National University and the University of Oxford have made an advanced in the field of perovskite nanosheets as promising new laser materials. The team overcame the inherent limitations of CsPbBr quantum dots using perovskite nanosheets, which provide enhanced light amplification abilities. 

The researchers introduced an innovative waveguide pattern, which increased the gain and thermal stability of the perovskite nanosheets. This pattern improved the optical confinement and heat dissipation, offering a solution to the limitations previously faced with quantum dots. The research team also pioneered a new ‘gain analysis’ method known as the ‘gain contour’. This novel technique provides a more in-depth understanding of gain saturation across various spectrum energies and optical stripe lengths.

Helio Display Materials has announced it will be moving its perovskite-based display materials (that were jointly invented within Cambridge and Oxford Universities) to pilot-scale production.

The materials generate light of the desired color by converting light rather than filtering it which provides power savings of up to 40% and a step change improvement in color gamut. With perovskites, the wavelength of emitted light can be tuned by chemical composition. This contrasts with quantum dots which rely on quantum confinement in identically sized nanometer scale particles. Color by composition massively simplifies the manufacturing process for perovskites vs. quantum dots and allows the use of standard chemical industry processes and equipment.

Researchers at North Carolina State University, Brown University and University at Buffalo have developed an autonomous system that can identify how to synthesize “best-in-class” materials for specific applications in hours or days. 

The new system, called SmartDope, was developed to address a persistent challenge regarding enhancing properties of perovskite quantum dots via “doping.”

Researchers from China's Hebei University of Technology and Chinese Academy of Sciences have found that increasing the diameter of single-wall carbon nanotubes (SWCNTs) in SWCNT/perovskite QD heterojunctions can improve the optoelectronic performance of the heterojunction between the two materials.

The team systematically tested the performance effects of varying diameters of SWCNTs, a single layer of carbon atoms that form a hexagonal lattice rolled into a seamless cylinder, with different band gaps, or the amount of energy required for an electron to conduct electric current, in heterojunction films with perovskite QDs. Their study indicated that increasing the diameter of SWCNTs improved the responsivity, detectivity and response time of this type of heterojunction film. This effect may be mediated by the enhanced separation and transport of photogenerated excitons, an energy-carrying, neutrally charged electron that combines with a positive electron hole, in the film.

TCI has launched a range of molecular dopants that can significantly increase the charge carrier density and modify the energy levels in organic electronics devices. Molecular dopants offer a versatile platform to tune the optoelectrical and electrical properties of organic semiconductors to application-specific demands, allowing advantages like increasing the electrical conductivity and mobility by orders of magnitude and improving contact properties in various electronic and optoelectronic devices.

TCI's p-type and n-type dopants can be applied to various organic electronics devices, such as: carrier transport layers of organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), perovskite solar cells (PSCs), and perovskite quantum dot LEDs, as well as active layers of organic field-effect transistors (OFETs), OPVs, and thermoelectric devices in the field of organic electronics research.

Canon has announced that it has developed perovskite quantum-dot inks for use in next-generation displays, with improved durability and potential for application in high-image-quality displays.

Quantum dots are semiconductor nanocrystals that measure only a few nanometers in diameter and can emit light with high brightness and high color purity. Displays with quantum-dot technology are attracting growing attention due to their wide color gamut that makes possible high visual expressiveness. Therefore, quantum dots for display is sought to achieve higher color purity and higher light utilization efficiency. In addition, though cadmium (Cd) has thus far been the preferred material for quantum dots, due to environmental concerns, there is a growing interest in Cd-free materials.

Researchers fromKorea's Pohang University of Science and Technology (POSTECH), Ajou University, Daegu Gyeongbuk Institute of Science and Technology (DGIST) and Kookmin University have designed new polymeric hole transport materials that constitute a crucial element in perovskite quantum dot solar cells, leading to significant increase in their efficiency. 

The team's hole transport materials include polymers based on sulfur and selenium compounds. These polymers exhibit structural features, such as planarization and locking of intermolecular arrangements, which increase charge mobility. Furthermore, asymmetric alkyl substituents of the polymers facilitate molecular interactions, thereby complementing the electrical properties of cells.