A5100643557- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Advanced Photocatalysis Techniques
- Copper-based nanomaterials and applications
- Nanocluster Synthesis and Applications
- Perovskite Materials and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Silicon Nanostructures and Photoluminescence
- Nanowire Synthesis and Applications
- Catalytic Processes in Materials Science
- CO2 Reduction Techniques and Catalysts
- ZnO doping and properties
- Electrocatalysts for Energy Conversion
- Semiconductor Quantum Structures and Devices
- Carbon and Quantum Dots Applications
- Magnetic properties of thin films
- Gas Sensing Nanomaterials and Sensors
- Carbon Nanotubes in Composites
- Advanced biosensing and bioanalysis techniques
- Pickering emulsions and particle stabilization
- Luminescence and Fluorescent Materials
- Photonic Crystals and Applications
- Organic Light-Emitting Diodes Research
- Advanced battery technologies research
- Ammonia Synthesis and Nitrogen Reduction
Korea Advanced Institute of Science and Technology
2016-2025
Daejeon University
2014-2020
Government of the Republic of Korea
2014-2020
Kootenay Association for Science & Technology
2018-2020
ORCID
2020
Los Alamos National Laboratory
2008-2015
The University of Texas at Austin
2004-2010
Seoul National University
2003
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHighly Stable Cesium Lead Halide Perovskite Nanocrystals through in Situ Inorganic PassivationJu Young Woo†‡, Youngsik Kim‡§, Jungmin Bae#, Tae Gun Kim∥#, Jeong Won Doh C. Lee*†, and Sohee Jeong*‡§View Author Information† Department of Chemical Biomolecular Engineering (BK21+ Program), KAIST Institute for the NanoCentury, Korea Advanced Science Technology (KAIST), Daejeon 305-701, Korea‡ Nano-Convergence Research Division, Machinery Materials...
CdSe/Zn1-X CdX S core/shell heterostructured quantum dots (QDs) with varying shell thicknesses are studied as the active material in a series of electroluminescent devices. "Giant" QDs (e.g., CdSe core radius 2 nm and Zn1-X thickness 6.3 nm) demonstrate high device efficiency (peak EQE = 7.4%) record-high brightness (>100 000 cd m(-2) ) deep-red emission, along improved stability.
PbSe nanocrystal quantum dots (NQDs) are a promising active material for range of optoelectronic devices, including solar cells, high-sensitivity infrared (IR) photodetectors, and IR-emitting diodes lasers. However, device realization has been constrained by these NQDs' chemical instability toward oxidation, which leads to uncontrollable changes in optical electronic properties. Here, we present simple method enhance the stability NQDs against oxidation improve their properties through...
We investigate the operational instability of quantum dot (QD)-based light-emitting diodes (QLEDs). Spectroscopic analysis on QD emissive layer within devices in chorus with optoelectronic and electrical characteristics discloses that device efficiency QLEDs under operation is indeed deteriorated by two main mechanisms. The first luminance drop running owing to accumulation excess electrons QDs, which escalates possibility nonradiative Auger recombination processes QDs. other electron...
Colloidal Ag(In,Ga)S2 nanocrystals (AIGS NCs) with the band gap tunability by their size and composition within visible range have garnered surging interest. High absorption cross-section narrow emission linewidth of AIGS NCs make them ideally suited to address challenges Cd-free in wide-ranging photonic applications. However, shown relatively underwhelming photoluminescence quantum yield (PL QY) date, primarily because coherent heteroepitaxy has not been realized. Here, we report for...
Colloidal FePt nanocrystals, 6 nm in diameter, were synthesized and then coated with silica (SiO2) shells. The shell thickness could be varied from 10 to 25 nm. As-made FePt@SiO2 nanocrystals have low magnetocrystalline anisotropy due a compositionally disordered core. When films of particles are annealed under hydrogen at 650 °C or above, the core transforms ordered L10 phase, superparamagnetic blocking temperatures exceeding room temperature obtained. SiO2 prevents coalescence annealing up...
The fast degradation of lead selenide (PbSe) nanocrystal quantum dots (NQDs) in ambient conditions impedes widespread deployment the highly excitonic, thus versatile, colloidal NQDs. Here we report a simple situ post-synthetic halide salt treatment that results size-independent air stability PbSe NQDs without significantly altering their optoelectronic characteristics. From TEM, NMR, and XPS DFT calculations, propose unprecedented can be attributed to successful passivation under-coordinated...
Multiple lamellar {111} twins are observed in GaAs, GaP, and InAs nanowires synthesized by supercritical fluid−liquid−solid (SFLS) solution−liquid−solid (SLS) approaches. All of these have zinc blende (cubic) crystal structure grow predominantly the 〈111〉 direction. The bisect perpendicular to their growth direction give them a "bamboo"-like appearance TEM images. In contrast, Si Ge with do not exhibit twins, even though this is common twin plane relatively low energy diamond cubic Si....
In this study, we synthesized Ge nanocrystals and studied the effects of variables such as solvents, reducing agents, reaction temperature, capping ligands. The resulting showed infrared photoluminescence with quantum yields high ∼8% enhanced resistance to oxidation. Size analysis samples by transmission electron microscopy revealed that size dependence emission is consistent confinement.
Thick inorganic shells endow colloidal nanocrystals (NCs) with enhanced photochemical stability and suppression of photoluminescence intermittency (also known as blinking). However, the progress using thick-shell heterostructure NCs in applications has been limited due to low quantum yield (PL QY ≤ 60%) at room temperature. Here, we demonstrate CdS/CdSe/CdS seed/spherical well/shell (SQW) geometry that exhibit near-unity PL temperature blinking. In SQW NCs, lattice mismatch is diminished...
Advance in wet chemistry enables the sophisticated design of nanocrystal quantum dots (QDs) and allows unprecedented color purity brightness, promising their useful applications a variety light-emitting applications. A representative example is core/shell heterostructures, which charge carriers are effectively decoupled from structural artifacts to generate photons efficiently. Despite development widely accepted synthetic protocols for Cd- or Pb-based QDs, progress heterostructuring...
Nanomaterials (NMs) are mostly synthesized by chemical and physical methods, but biological synthesis is also receiving great attention. However, the mechanisms for producibility of NMs, crystalline versus amorphous, not yet understood. Here we report biosynthesis 60 different NMs employing a recombinant Escherichia coli strain coexpressing metallothionein, metal-binding protein, phytochelatin synthase that synthesizes peptide phytochelatin. Both an in vivo method live cells vitro cell...
Many heterogeneous catalytic reactions occur at high temperatures, which may cause large energy costs, poor safety, and thermal degradation of catalysts. Here, we propose a light-assisted surface reaction, catalyze the reaction using both light heat as an source. Conventional metal catalysts such ruthenium, rhodium, platinum, nickel, copper were tested for CO2 hydrogenation, ruthenium showed most distinct change upon irradiation. was strongly adsorbed onto surface, forming hybrid orbitals....
We report the photocatalytic conversion of CO2 to CH4 using CuPt alloy nanoclusters anchored on TiO2. As size decreases, activity improves significantly. Small strongly bind intermediates and have a stronger interaction with TiO2 support, which also contributes an increased generation rate. The alloying effects prove be key efficient reduction, highlighting strategic platform for design photocatalysts conversion.
Advances in nanotechnology have enabled precise design of catalytic sites for CO2 photoreduction, pushing product selectivity to near unity. However, activity most nanostructured photocatalysts remains underwhelming due fast recombination photogenerated electron-hole pairs and sluggish hole transfer. To address these issues, we construct colloidal CdS nanosheets (NSs) with the large basal planes terminated by S2- atomic layers as intrinsic (CdS-S2- NSs). Experimental investigation reveals...
Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper-realistic images with free-form factors. Accordingly, nondestructive and scalable process capable of rendering multicolored QD patterns on scale several micrometers needs to be established. Here, direct photopatterning heavy-metal-free QDs reported using branched light-driven ligand crosslinkers (LiXers) containing multiple azide units. The LiXers effectively interlock films via...
There is an evergrowing demand for environment-friendly processes to synthesize ammonia (NH3) from atmospheric nitrogen (N2). Although diazotrophic N2 fixation represents undeniably "green" process of NH3 synthesis, the slow reaction rate makes it less suitable industrially meaningful large-scale production. Here, we report photoinduced using a hybrid system composed colloidal quantum dots (QDs) and aerobic N2-fixing bacteria, Azotobacter vinelandii. Compared case where A. vinelandii cells...
Direct optical lithography presents a promising patterning method for colloidal quantum dots (QDs). However, additional care needs to be taken prevent deterioration of the properties QDs upon patterning, especially InP-based QDs. This study proposes an efficient high-resolution using photoacid generator while preserving their properties. Specifically, our solid-state ligand exchange strategy, replacing chloride ligands with long-chain amine/carboxylate pair ligands, successfully recovered...
We examine the effects of chlorine-passivation Cd surface atoms on photocatalytic H2O reduction by CdSe NCs. Transient absorption spectroscopy reveals that Cl passivation removes electron trap states in NCs, which is also reflected an increase photoluminescence quantum yield, e.g., from 9 to 22% after treatment. Size-tunable energy NCs enable systematic investigation defects and their effect hydrogen generation rate. It turns out that, depending band-edge levels, may enhance or inhibit...
We report on the fabrication of a siloxane-encapsulated quantum dot (QD) film (QD-silox film), which exhibits stable emission intensity for over 1 month even at elevated temperature and humidity. QD-silox films are solidified via free radical addition reaction between oligosiloxane resin ligand molecules QDs. prepare QD-oligosiloxane by sol–gel condensation silane precursors with QDs blended in precursor solution, forgoing ligand-exchange The resulting remains optically clear after 40 days...
We present multifunctional dendrimer ligands that serve as the charge injection controlling layer well adhesive at interfaces between quantum dots (QDs) and electron transport (ETL) in dot light-emitting diodes (QLEDs). Specifically, we use primary amine-functionalized (e.g., a series of poly(amidoamine) dendrimers (PADs, also referred to PAMAM)) bind surface QDs by replacing native (oleic acids) ZnO ETL. PAD control rate from ETL into altering electronic energy levels thereby improve...