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Although controlling the doping on the atomic length scale is difficult, Colloidal CdSe quantum dots display a promising roadmap for the production of hybrid solar cells with increased power conversion efficiency. Solution processing makes the process of optimizing quantum dot based solar cells' effectiveness a common tactic for improving quantum dot and polymer hybrids' performance.
Source link: https://doi.org/10.1149/06615.0001ecst
Peter Pringsheim, a German physicist, suggested that anti-Stokes exposure, which led to the cooling of bulk matter in 1929. Photons of shorter wavelength than those of the dramatic light due to thermal absorption show the emission result in anti-Stokes photons of a shorter wavelength than that of the dramatic light due to thermal absorption. One must irradiate a sample with laser light in the red tail of the absorption spectrum in order to cool a solid by lasers. The material that was to be cooled will first absorb a photon and absorb additional energy from a phonon to create a blue-shifted photon of increased brightness. Laser cooling can also be adjusted so that spontaneous anti-Stokes luminescence cooling compensates for the stimulated quantum defect heating. A thermally balanced laser such as this would not suffer from thermal defocusing or heat damage; thus, such solid-state-lasers may have higher output capabilities. The material must be solids, so the rate of cooling must be high, and nearly all of the anti-Stokes luminescence must leave the material unreabsorbed. However, as the temperature decreases, the cooling capacity of rare-earth ions approaches zero. Direct bandgap semiconductors are a viable laser cooling candidate material, thanks to their strong electron-phonon coupling of Group II-VI semiconductors and core-shell quantum dot structure, which minimizes the absorption of the anti-Stokes luminescence. We have chosen to investigate CdSe/ZnS quantum dots for laser cooling applications due to the possibility of near-unity quantum efficiency in CdSe/ZnS.
Source link: https://doi.org/10.1149/ma2017-02/53/2235
The Mn2+ ions diffused within MnyZn1-ySe/ZnSe nanocrystals, acting as localized luminescent centers, and their density can be controlled with the Mn percentage in the alloyed core in the second case. The ions are excited by energy transfers from excitons in the ZnSe, and given the Mn2+ first excited state, thermoactivated reverse energy transfer occurred also, with ZnSe excitons present.
Source link: https://doi.org/10.1149/1.3700412
The XRD results reveal the emergence of mixed phases of CdSe and CdTe with a grain size of 12. 6 nm. The number of spherical CdSe/CdTe core-shell QDs is expected to be in the range of 8 to 10 nm, according to TEM results. At 585 nm, the demonstrated monodispersed lattice structure of CdSe/CdTe QDs has excellent PL emission characteristics, making it ideal for photovoltaic applications. The UV-Vis absorption bands at 455 nm and 560 nm report exciton leakage due to the type II matrix of CdSe/CdTe QDs.
Source link: https://doi.org/10.1155/2022/6316716
TiO 2 nanotubes, one of a series of pristine TiO 2 nanomaterials that is active under ultraviolet irradiation for photoelectric/photocatalytic applications, is one type of pristine TiO 2 nanotubes . CdSe QDs, coupled with tunable band gaps, provide new opportunities for harvesting light energy in the visible and infrared regions of solar light . Consequently, the decoration of CdSe QDs on TiO 2-x TNTs is expected to greatly increase the solar energy absorption and TNT's photocatalytic activities. Samples of TNT and T-TNT were decorated by dropping 150-L CdSe QDs solutions in 5 cycles, and approximately 12. 5 g CdSe QDs were added to samples. Different CdSe QDs were dispersed onto a thermal oxide silicon wafer and characterized by an atomic force microscope, indicating that the number of monodisperse CdSe QDs is approximately 10-30 nm, as shown in Fig. As shown in the inset image of Fig. 7, the color change of CdSe QDs solutions under visible light and UV fluorescent indicates the photoexcitation properties of CdSe QDs. After implementing Ti 3+ sites in the surface of TNT, the color of TNT and TNT transformed by different CdSe QDs and the inset picture shows the hue of T-TNT and T-TNT and T-TNT decoration changes to black or dark blue. Author Kang Du would like to acknowledge the financial assistance from the KD program at University College of Southeast Norway and the Norwegian Research Council-FRINATEK program.
Source link: https://doi.org/10.1149/ma2017-01/27/1305
MBE p-GaN growth over II-VI semiconductor nanocrystals on an MOCVD n-GaN template is the subject of our current research. Atop a sapphire wafer, the starting material was about 2 microns of n-type GaN MOCVD-based clay atop a sapphire wafer. Utilizing a nitrogen plasma source, a p-type MBE GaN layer of 2500 A was created.
Source link: https://doi.org/10.1149/1.2357239
The change of quantum confinement capability alone could explain the change in quantum confinement capability, rather than the change of quantum confinement potential only. According to the micro-photoluminescence spectra at 4. 2 K, the photoluminescence peaks of the islands' photoluminescence peaks of 166 meV. First, the sheet thickness of the samples with increasing thickness of the CdSe layer will increase, and the large islands' with lower exciton ground state energy will grow.
Source link: https://doi.org/10.7498/aps.55.2628
The relationship between the nanoparticle size and the absorption peak of CdSe quantumn dots was explored by UV-VIS-NIR spectroscopy, and the determination of third-order nonlinear susceptibility of quantumn dots by different excitation wavelengths was investigated by a picosecond Z-scan technique with different excitation wavelengths. With a minimum value of 2. 0-10-11 esu and a maximum size of 4. 3nm and the excitation wavelength of 532nm, which was near to the resonance, the third-order nonlinear susceptibility exhibited a maximum value of 2. 010-11 esu.
Source link: https://doi.org/10.7498/aps.57.6557
The nuclear spin fluctuation time in a transverse magnetic field of 250 mT is now 294 ps, due to the fact that the presence of a magnetic field makes the nuclear spin fluctuations irrelevant. The spin dynamics of the exciton spin dynamics are dominated by inhomogenous dephasing in high magnetic fields, according to the magnetic field dependence of the exciton spin dynamics.
Source link: https://doi.org/10.7498/aps.61.207202
The fine band structures and the structure's properties are confirmed by the sample's surface photovoltage spectrum. Both PL line broadens and SPV response intensities rise with the decrease of the sample's grain size. The change in the surface photoacoustic signal intensity of the samples synthesized at varying pH levels is inconsistent with that of the SPV response intensity of the samples synthesized at varying pH levels. In addition, the fine band structures at the surfaces and grain boundaries of CdSe QDs prepared are investigated by the SPV spectra of the samples at different pH levels.
Source link: https://doi.org/10.7498/aps.62.066801
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