Phys.org December 10, 2024 An international team of researchers (Israel, USA – UT Austin, Los Alamos National Laboratory, Germany, Italy) harnessed the potential of radially polarized photons for classical and quantum communication applications to demonstrate an on-chip, room-temperature device, which generated highly directional radially polarized photons at very high rates. The photons were emitted from a giant CdSe/CdS colloidal quantum dot (gQD) accurately positioned at the tip of a metal nanocone centered inside a hybrid metal-dielectric bullseye antenna. They showed that the emitted photons could have a very high degree of radial polarization, based on a quantitative metric. According to […]
Tag Archives: quantum dot
Restoring quantum dot solar cells as if ‘flattening crumpled paper’
Nanowerk October 4, 2024 All-inorganic CsPbI3 perovskite quantum dots (PQDs) hold significant potential for next-generation photovoltaics due to their unique optoelectronic properties. Initially used long-chain ligands in PQDs synthesis stabilized the black phase but hindered charge transport when employed to solar cells, necessitating their replacement with shorter ones leading to the formation of surface defects and loss of tensile strain, resulting in the transition to the undesired orthorhombic phase and compromising PQD solar cell performance. To address these issues researchers at the Republic of Korea developed an efficient ligand-exchange process utilizing a multifaceted anchoring ligand, 2-thiophenemethylammonium iodide (ThMAI). The larger […]
Researchers develop world’s most efficient quantum dot solar cell
Nanowerk February 21, 2024 Research has predominantly focused on inorganic cation perovskite-based colloidal quantum dots (PQDs) even though organic cation PQDs have more favorable bandgaps. Researchers in South Korea developed solar cells using narrow bandgap organic cation based PQDs and demonstrated substantially higher efficiency compared with their inorganic counterparts. They employed an alkyl ammonium iodide-based ligand exchange strategy, which proved to be substantially more efficient in replacing the long-chain oleyl ligands than conventional methyl acetate-based ligand exchange while stabilizing the α phase of organic PQDs in ambient conditions. They showed a solar cell with the organic cation PQDs with high […]
Mini electricity generator made from quantum dots
Phys.org January 18, 2022 The major challenges toward the exploitation of graphene nanoribbons (GNRs) in electronic applications include reliable contacting, and the preservation of their physical properties upon device integration. An international team of researchers (Switzerland, UK, Germany) described the quantum dot behavior of atomically precise GNRs integrated in a device geometry. The devices consist of a film of aligned five-atom-wide GNRs (5-AGNRs) transferred onto graphene electrodes with a sub 5 nm nanogap. They demonstrated that the narrow-bandgap 5-AGNRs exhibit metal-like behavior at room temperature and single-electron transistor behavior for temperatures below 150 K. They obtained addition energies in the […]
Nanocrystal ‘factory’ could revolutionize quantum dot manufacturing
Phys.org March 15, 2019 Researchers at North Carolina State University have developed a microfluidic system (called NC Factory) which starts with cesium lead bromide perovskite quantum dots and introduced various halide salts to precisely tune their fluorescence color across the entire spectrum of visible light. Anions in these salts replace the bromine atoms in the green-emitting dots with either iodine atoms (to move toward the red end of the spectrum) or chlorine atoms (to move toward blue). Coupled with continuous process monitoring, the system can precisely control both chemical composition and processing parameters. It can be used to continuously manufacture […]
A new kind of quantum bits in two dimensions
Nanowerk March 19, 2018 An international team of researchers (Germany, Austria, Hungary, UK) succeeded in developing a new type of quantum dots by combining graphene and hexagonal boron nitride, also a single layer of material quite like graphene except that it is insulating. The two layers cannot perfectly match when put one on top of the other resulting in an extremely regular wave-like spatial oscillation of the graphene layer out of the perfect plane. The potential landscape created by the regular superstructure allows for accurately placing the quantum dot, or even moving it continuously and thus smoothly changing its properties… […]