Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Photodetecting Heterostructures from Graphene and Encapsulated Colloidal Quantum Dot Films.

ABSTRACT: Heterostructure devices consisting of graphene and colloidal quantum dots (QDs) have been remarkably successful as photodetectors and have opened the door to technological applications based on the combination of these low-dimensional materials. This work explores the photodetection properties of a heterostructure consisting of a graphene field effect transistor covered by a film of silica-encapsulated colloidal QDs. Defects at the surface of the silica shell trap optically excited charge carriers, which simultaneously enables photodetection via two mechanisms: photogating, resulting in a net p-doping of the device, and Coulombic scattering of charge carriers in the graphene, producing an overall decrease in the current magnitude.

SUBMITTER: Black A

PROVIDER: S-EPMC6776979 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Photodetecting Heterostructures from Graphene and Encapsulated Colloidal Quantum Dot Films.

Black Andrés A Urbanos Fernando J FJ Roberts Jonathan J Acebrón María M Bernardo-Gavito Ramón R Juárez Beatriz H BH Robinson Benjamin J BJ Young Robert J RJ Vázquez de Parga Amadeo L AL Granados Daniel D

ACS omega 20190917 14

Heterostructure devices consisting of graphene and colloidal quantum dots (QDs) have been remarkably successful as photodetectors and have opened the door to technological applications based on the combination of these low-dimensional materials. This work explores the photodetection properties of a heterostructure consisting of a graphene field effect transistor covered by a film of silica-encapsulated colloidal QDs. Defects at the surface of the silica shell trap optically excited charge carrie ...[more]

PMID: 31592149

Similar Datasets

Electrical Transport Properties of PbS Quantum Dot/Graphene Heterostructures.

Project description:The integration of PbS quantum dots (QDs) with graphene represents a notable advancement in enhancing the optoelectronic properties of quantum-dot-based devices. This study investigated the electrical transport properties of PbS quantum dot (QD)/graphene heterostructures, leveraging the high carrier mobility of graphene. We fabricated QD/graphene/SiO2/Si heterostructures by synthesizing p-type monolayer graphene via chemical vapor deposition and spin-coating PbS QDs on the surface. Then, we used a low-temperature electrical transport measurement system to study the electrical transport properties of the heterostructure under different temperature, gate voltage, and light conditions and compared them with bare graphene samples. The results indicated that the QD/graphene samples exhibited higher resistance than graphene alone, with both resistances slightly increasing with temperature. The QD/graphene samples exhibited significant hole doping, with conductivity increasing from 0.0002 Ω-1 to 0.0007 Ω-1 under gate voltage modulation. As the temperature increased from 5 K to 300 K, hole mobility decreased from 1200 cm2V-1s-1 to 400 cm2V-1s-1 and electron mobility decreased from 800 cm2V-1s-1 to 200 cm2V-1s-1. Infrared illumination reduced resistance, thereby enhancing conductivity, with a resistance change of about 0.4%/mW at a gate voltage of 125 V, demonstrating the potential of these heterostructures for infrared photodetector applications. These findings offer significant insights into the charge transport mechanisms in low-dimensional materials, paving the way for high-performance optoelectronic devices.

| S-EPMC11510120 | biostudies-literature

Spray Coated Colloidal Quantum Dot Films for Broadband Photodetectors.

Project description:A technique for scalable spray coating of colloidal CdSeTe quantum dots (QDs) for photovoltaics and photodetector applications is presented. A mixture solvent with water and ethanol was introduced to enhance the adhesive force between QDs and the substrate interface. The performance of the detector reached the highest values with 40 spray coating cycles of QD deposition. The photodetectors without bias voltage showed broadband response in the wavelength range of 300-800 nm, and high responsivity of 15 mA/W, detectivity of more than 1011 Jones and rise time of 0.04 s. A large size QD-logo pattern film (10 × 10 cm2) prepared by the spray coating process displayed excellent uniformity of thickness and absorbance. The large area detectors (the active area 1 cm2) showed almost the same performance as the typical laboratory-size ones (the active area 0.1 cm2). Our study demonstrates that the spray coating is a very promising film fabrication technology for the industrial-scale production of optoelectronic devices.

| S-EPMC6955664 | biostudies-literature

Energy level tuned indium arsenide colloidal quantum dot films for efficient photovoltaics.

Project description:We introduce indium arsenide colloidal quantum dot films for photovoltaic devices, fabricated by two-step surface modification. Native ligands and unwanted oxides on the surface are peeled off followed by passivating with incoming atomic or short ligands. The near-infrared-absorbing n-type indium arsenide colloidal quantum dot films can be tuned in energy-level positions up to 0.4 eV depending on the surface chemistry, and consequently, they boost collection efficiency when used in various emerging solar cells. As an example, we demonstrate p-n junction between n-type indium arsenide and p-type lead sulfide colloidal quantum dot layers, which leads to a favorable electronic band alignment and charge extraction from both colloidal quantum dot layers. A certified power conversion efficiency of 7.92% is achieved without additionally supporting carrier transport layers. This study provides richer materials to explore for high-efficiency emerging photovoltaics and will broaden research interest for various optoelectronic applications using the n-type covalent nanocrystal arrays.

| S-EPMC6189201 | biostudies-literature

Integrating an electrically active colloidal quantum dot photodiode with a graphene phototransistor.

Project description:The realization of low-cost photodetectors with high sensitivity, high quantum efficiency, high gain and fast photoresponse in the visible and short-wave infrared remains one of the challenges in optoelectronics. Two classes of photodetectors that have been developed are photodiodes and phototransistors, each of them with specific drawbacks. Here we merge both types into a hybrid photodetector device by integrating a colloidal quantum dot photodiode atop a graphene phototransistor. Our hybrid detector overcomes the limitations of a phototransistor in terms of speed, quantum efficiency and linear dynamic range. We report quantum efficiencies in excess of 70%, gain of 10(5) and linear dynamic range of 110 dB and 3 dB bandwidth of 1.5 kHz. This constitutes a demonstration of an optoelectronically active device integrated directly atop graphene and paves the way towards a generation of flexible highly performing hybrid two-dimensional (2D)/0D optoelectronics.

| S-EPMC4915030 | biostudies-literature

The Surface Polarized Graphene Oxide Quantum Dot Films for Flexible Nanogenerators.

Project description:Abundant disorderly-distributed surface functional groups, such as hydroxyl, carboxyl, ether and amino groups, endow an isolated graphene oxide quantum dot (GOQD) the polar property due to the symmetry breaking, although the aggregated counterparts present no polarization owing to the random orientation. Here, flexible polarized films were fabricated using aggregated GOQDs with the assistance of external electric fields and their polarization was confirmed with the electrostatic force microscopy and polarization-electric field hysteresis loop. Such polarized GOQD films may induce charges under externally applied deformation. Here, we fabricated nanogenerators based on the films, which gave out an average current value of 0.12 μA and an average voltage value of 12 V under a mechanical force of 60 N. This work has proposed a convenient electric-field-assisted method to give the nanomaterials new functions, which can be generalized to other materials and found applications in various fields.

| S-EPMC5011759 | biostudies-literature

Colloidal HgTe Quantum Dot/Graphene Phototransistor with a Spectral Sensitivity Beyond 3 µm.

Project description:Infrared light detection enables diverse technologies ranging from night vision to gas analysis. Emerging technologies such as low-cost cameras for self-driving cars require highly sensitive, low-cost photodetector cameras with spectral sensitivities up to wavelengths of 10 µm. For this purpose, colloidal quantum dot (QD) graphene phototransistors offer a viable alternative to traditional technologies owing to inexpensive synthesis and processing of QDs. However, the spectral range of QD/graphene phototransistors is thus far limited to 1.6 µm. Here, HgTe QD/graphene phototransistors with spectral sensitivity up to 3 µm are presented, with specific detectivities of 6 × 108 Jones at a wavelength of 2.5 µm and a temperature of 80 K. Even at kHz light modulation frequencies, specific detectivities exceed 108 Jones making them suitable for fast video imaging. The simple device architecture and QD film patterning in combination with a broad spectral sensitivity manifest an important step toward low-cost, multi-color infrared cameras.

| S-EPMC7967065 | biostudies-literature

Graphene quantum dot-coated polystyrene microsphere multilayer colloidal crystals with distributed Bragg reflector absorption.

Project description:Distributed Bragg reflector (DBR) absorptive materials have broad applications in optical fibre communications, solar cells, and other fields. This study adopts dispersion polymerization to prepare monodisperse polystyrene (PS) microspheres. Graphene quantum dots (GQDs) are prepared using the ultrasonic dispersion method. By coating GQDs on surfaces of PS spheres, the micron-sized core-extremely thin shell, PS@GQDs structures are self-assembled successfully. Finally, using the improved gravity sedimentation, the unconventional colloidal crystals of PS@GQDs structures are fabricated and characterized for the first time. The unconventional colloidal crystals of PS@GQDs exhibit tunable DBR scattering absorption, ranging from near-ultraviolet to near-infrared, which is unlike the conventional DBR. The experimental observations and measurements indicate that the modification of the PS surface significantly red-shifted in the ultraviolet-near infrared bands (300-1200 nm). The interference fringes of GQDs of various sizes with PS spheres formed Bragg reflectors, creating larger amplitudes below 1200 nm. Raman spectra show that the colloidal crystals display the peaks of polystyrene with a red-shift. The numerical simulations indicate that the DBR phenomena can be understood as the topological excitations at the structure transitions in the plasmon resonances and photonic band crossovers.

| S-EPMC11906851 | biostudies-literature

Single PbS colloidal quantum dot transistors.

Project description:Colloidal quantum dots are sub-10 nm semiconductors treated with liquid processes, rendering them attractive candidates for single-electron transistors operating at high temperatures. However, there have been few reports on single-electron transistors using colloidal quantum dots due to the difficulty in fabrication. In this work, we fabricated single-electron transistors using single oleic acid-capped PbS quantum dot coupled to nanogap metal electrodes and measured single-electron tunneling. We observed dot size-dependent carrier transport, orbital-dependent electron charging energy and conductance, electric field modulation of the electron confinement potential, and the Kondo effect, which provide nanoscopic insights into carrier transport through single colloidal quantum dots. Moreover, the large charging energy in small quantum dots enables single-electron transistor operation even at room temperature. These findings, as well as the commercial availability and high stability, make PbS quantum dots promising for the development of quantum information and optoelectronic devices, particularly room-temperature single-electron transistors with excellent optical properties.

| S-EPMC10657373 | biostudies-literature

Hedgehog Zinc Oxide-Graphene Quantum Dot Heterostructures as Photocatalysts for Visible-Light-Driven Water Splitting.

Project description:The development of efficient photocatalysts for sustainable hydrogen production via water splitting is vital for advancing renewable energy technologies. In this study, we present the synthesis and characterization of a novel visible-light-active photocatalyst comprising hedgehog-shaped zinc oxide (ZnO) nanostructures coupled with graphene quantum dots (GQDs). Optical properties assessed by UV-visible and photoluminescence (PL) spectroscopy revealed that the ZnO/GQDs heterostructure possessed a reduced band gap (2.86 eV) compared with pristine ZnO (3.10 eV), resulting in improved light absorption and charge separation. Electrochemical analyses indicated a significantly higher photocurrent response and lower charge transfer resistance for the ZnO/GQDs heterostructure compared with the pristine ZnO nanostructure. Photocatalytic tests demonstrated that the ZnO/GQDs heterostructure achieved over 3-fold higher hydrogen (H2) production rates, with an apparent quantum yield (AQY) of 1.51% at 440 nm, and maintained stable activity over prolonged reaction periods. These results highlight the enhanced photocatalytic efficiency and stability of the ZnO/GQDs heterostructure, underscoring its potential as a high-performance photocatalyst for sustainable hydrogen generation. The synergistic effects between ZnO nanostructures and GQDs offer valuable insights into the design of advanced photocatalytic materials for renewable energy applications.

| S-EPMC11447729 | biostudies-literature

Enhanced Thermal Stability of Conductive Mercury Telluride Colloidal Quantum Dot Thin Films Using Atomic Layer Deposition.

Project description:Colloidal quantum dots (CQDs) are valuable for their potential applications in optoelectronic devices. However, they are susceptible to thermal degradation during processing and while in use. Mitigating thermally induced sintering, which leads to absorption spectrum broadening and undesirable changes to thin film electrical properties, is necessary for the reliable design and manufacture of CQD-based optoelectronics. Here, low-temperature metal-oxide atomic layer deposition (ALD) was investigated as a method for mitigating sintering while preserving the optoelectronic properties of mercury telluride (HgTe) CQD films. ALD-coated films are subjected to temperatures up to 160 °C for up to 5 h and alumina (Al2O3) is found to be most effective at preserving the optical properties, demonstrating the feasibility of metal-oxide in-filling to protect against sintering. HgTe CQD film electrical properties were investigated before and after alumina ALD in-filling, which was found to increase the p-type doping and hole mobility of the films. The magnitude of these effects depended on the conditions used to prepare the HgTe CQDs. With further investigation into the interaction effects of CQD and ALD process factors, these results may be used to guide the design of CQD-ALD materials for their practical integration into useful optoelectronic devices.

| S-EPMC11357074 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data