scispace - formally typeset
Search or ask a question
Topic

Potential well

About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the fabrication of the Cu2O quantum dots (QDs) emitting a controlled wavelength in the visible spectral range prepared by atomic layer deposition (ALD) was reported.
Abstract: This paper reports the fabrication of the Cu2O quantum dots (QDs) emitting a controlled wavelength in the visible spectral range prepared by atomic layer deposition (ALD). Cu2O thin film layers formed on the Al2O3 surface showed large density of islands via Volmer–Weber growth mode, which resulting in QD formation. As the number of ALD cycles was increased from 60 to 480, the spatial density and mean diameter of the Cu2O QDs increased systematically from 4.02 × 1011/cm2 to 2.56×1012/cm2 and from 2.1 to 3.2 nm, respectively. The absorption spectral results indicated that the electron energy transition in the Cu2O QDs was a direct process with the optical band gaps decreasing from 2.71 to 2.15 eV with increasing QD size from 2.1 to 3.2 nm because of the quantum confinement effect. The Cu2O QDs showed broad emission peaks composed of multiple elementary emission spectra corresponding to the Cu2O QD ensembles with a different size distribution. As the size of Cu2O QDs decreased, the shoulder peaks at the higher energy side developed due to the quantum confinement effect.

9 citations

Journal ArticleDOI
TL;DR: Distinct bandedge photoluminescence emission was observed in the mid-infrared spectral range and the quantum confinement effect estimated from the PL peak energy was within 40 meV, consistent with the average diameter of the nanowire being significantly larger than the exciton Bohr radius.
Abstract: We studied optical properties and photocurrent characteristics of PbS nanowires grown by chemical vapor deposition. Distinct bandedge photoluminescence (PL) emission was observed in the mid-infrared spectral range and the quantum confinement effect estimated from the PL peak energy was within 40 meV, consistent with the average diameter of the nanowire (∼70 nm) being significantly larger than the exciton Bohr radius (∼18 nm). We also demonstrated interdigit photo detectors making use of these PbS nanowires suspended between two pre-patterned Ti electrodes, where Ti also acted as metal catalyst for the nanowire growth. The threshold wavelength of the photocurrent was found to be ∼3 μm at room temperature.

9 citations

Journal ArticleDOI
TL;DR: First-principles calculations render CaFCl an attractive 2D material for applications in flexible nanoelectronics and optoelectronic devices and a strong interlayer quantum confinement effect.
Abstract: Two-dimensional (2D) ultra-wide bandgap (UWBG) semiconductors have attracted tremendous attention because of their unique electronic properties and promising applications. Using first-principles calculations, monolayer (bilayer) CaFCl has a cleavage energy of 0.93 J m−2 (0.72 J m−2), suggesting that the exfoliation of monolayer and few-layer materials from the bulk phase could be feasible. The CaFCl monolayer is an UWBG semiconductor with a direct bandgap of 6.62 eV. In addition to the dynamic and thermodynamic stability, it can remain thermally stable at 2200 K, suitable for operation in high-temperature environments. The bandgap of monolayer CaFCl can be tuned by external strain and layer thickness. The decrease of the layer thickness leads to not only a bandgap increase but also an indirect-to-direct bandgap transition, suggesting a strong interlayer quantum confinement effect. Under biaxial strain, the direct bandgap can also be turned into an indirect one. The adsorption of a tetrathiafulvalene (TTF) molecule introduces deep donor states in the gap of CaFCl. Under an external electric field with direction from CaFCl to TTF, the TTF-derived donor states move closer to the conduction band edge of CaFCl and then the adsorption complex becomes effectively n-doped. Furthermore, monolayer CaFCl exhibits pronounced optical absorption in the ultraviolet range of the solar spectrum. These results render CaFCl an attractive 2D material for applications in flexible nanoelectronic and optoelectronic devices.

9 citations

Journal ArticleDOI
TL;DR: In this paper, the role of dopants in achieving stable and deep blue emission with absolute unity photoluminescence (PL) quantum yield (QY) through Ce3+ and Tb3+ doping at high concentrations in 2D CH3NH3PbBr3 nanosheets (NSs) using a solvothermal method.
Abstract: Despite recent efforts, achieving stable deep blue emission with near unity quantum yield from lead-free perovskite has remained a great challenge. In this study, we have developed a novel strategy to achieve stable and deep blue emission with absolute unity photoluminescence (PL) quantum yield (QY) through Ce3+ and Tb3+ doping at high concentrations in 2D CH3NH3PbBr3 nanosheets (NSs) using a solvothermal method. We investigated the role of dopants in achieving the high QY and deep blue emission in a 2D perovskite using density functional theory (DFT) based calculations of its electronic structure. Our studies reveal that with Ce/Tb doping, the thickness of the NSs systematically goes down from 10 layers to bilayers (1.4 nm) at high doping levels and the bandgap of the 2D perovskite layer increases from 2.394 eV to 2.981 eV. The measured bandgap widening with doping is analyzed and explained on the basis of the quantum confinement effect and lattice contraction. Interestingly, by incorporating 70 mol% CeBr3 in the perovskite crystal, we achieved a deep blue emitting nanoplatelet with 100% QY, narrow linewidth (∼24 nm), and a color coordinate of (0.145, 0.054) closely matching with the standard color Rec. 2020 (0.131, 0.046) specification, making it one of the most efficient perovskite blue light emitters reported to date. We also demonstrate much improved storage stability of the Ce and Tb doped NS, fully consistent with the DFT calculations. The low temperature PL study reveals the coexistence of ordered and disordered orthorhombic phases. From DFT calculations, we show that the dopants stabilize the structure with lower formation energy and enrich the conduction band edge states without introducing deep trap states, which is responsible for the high PL QY. The calculation also reveals that Tb doping leads to a substantial increase in the bandgap, which is fully consistent with our experimental results. Finally, the Ce3+ doped CH3NH3PbBr3 blue-emitting nanoplatelet is used as a white light LED with CIE coordinates (0.334, 0.326). This work demonstrates a versatile approach to develop rare-earth doped deep blue-emitting 2D perovskites with exceptionally high PL QY and provides new insights into the structural stability and electronic structure of rare-earth doped 2D perovskites.

9 citations

Journal ArticleDOI
TL;DR: Titania-germanium (TiO(2)-Ge) becomes a promising material for the next generation of photovoltaics as well as thermoelectric devices and could also be used for photo-thermo-electric applications.
Abstract: The introduction of germanium (Ge) into titania (TiO2) creates an attractive semiconductor. The new semiconductor is named titania–germanium (TiO2–Ge). Ge dots are dispersed in the distorted TiO2 matrix of TiO2–Ge. The quantum Bohr radius of Ge is 24.3 nm, and hence the properties of the Ge dot can be varied by tailoring its size if it is smaller than its Bohr radius due to the quantum confinement effect (QCE). Therefore, simply by changing the Ge concentration, the morphology of TiO2–Ge can be varied within a wide range. Consequently, the optical, electronic and thermal properties of TiO2–Ge can be tailored. TiO2–Ge becomes a promising material for the next generation of photovoltaics as well as thermoelectric devices. It could also be used for photo-thermo-electric applications.

9 citations


Network Information
Related Topics (5)
Band gap
86.8K papers, 2.2M citations
91% related
Thin film
275.5K papers, 4.5M citations
88% related
Graphene
144.5K papers, 4.9M citations
85% related
Carbon nanotube
109K papers, 3.6M citations
85% related
Oxide
213.4K papers, 3.6M citations
84% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
202215
202164
202062
201940
201875