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Potential well
About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.
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TL;DR: In this paper, the molar ratio of methylammonium bromide (MABr) and hexadecammonium (HABr) was tuned to obtain the absorption spectrum of the monolayer (HA)2PbBr4 perovskite NPLs.
Abstract: We report the preparation of monolayer (n = 1), few-layer (n = 2–5) and 3D (n = ∞) organic lead bromide perovskite nanoplatelets (NPLs) by tuning the molar ratio of methylammonium bromide (MABr) and hexadecammonium bromide (HABr). The absorption spectrum of the monolayer (HA)2PbBr4 perovskite NPLs shows about 138 nm blue shift from that of 3D MAPbBr3 perovskites, which is attributed to strong quantum confinement effect. We further investigate the two-photon photoluminescence (PL) of the NPLs and measure the exciton binding energy of monolayer perovskite NPLs using linear absorption and two-photon PL excitation spectroscopy. The exciton binding energy of monolayer perovskite NPLs is about 218 meV, which is far larger than tens of meV in 3D lead halide perovskites.
47 citations
TL;DR: In this paper, the authors studied the use of the effective potential in a triangular well formed between the oxide and the depletion field of the semiconductor, and determined the quantization energy of the carriers in the potential well and their mean set-back from the interface.
47 citations
TL;DR: The evolution of the gap of a nanoscaled insulator material, namely, Gd(2)O(3), has been observed by means of vacuum ultraviolet excitation spectra of a dopant and shows that, in spite of the strong ionic character of the material, the amount of covalency is important enough for creating a significant delocalization of the electron with regard to its hole.
Abstract: The evolution of the gap of a nanoscaled insulator material, namely, Gd(2)O(3), has been observed by means of vacuum ultraviolet excitation spectra of a dopant (Eu(3+)). The nanoparticles have been synthesized by the low energy cluster beam deposition technique and grown afterward by different annealing steps. A gap shift towards the blue is observed, similar to what is observed in semiconductor nanoparticles. Despite the strong ionic character of the material, the evolution exhibits a behavior similar to covalent materials. The evolution of the gap for Gd(2)O(3) follows the same empiric rule that has been derived for semiconductors (ZnO, CuBr, Si, and CdS). It shows that, in spite of the strong ionic character of the material (0.9 on the scale of Phillips), the amount of covalency is important enough for creating a significant delocalization of the electron with regard to its hole.
47 citations
TL;DR: In this article, the nonlinear optical properties of Fe2O3 nanoparticles were investigated by the signal-beam Z-scan technique with Ar+ and Ne-He lasers, and the largest reported effective nonlinear coefficient, n 2 =−8.07×10 −7 cm 2 / W, was obtained.
Abstract: Nonlinear optical properties of Fe2O3 nanoparticles were investigated by the signal-beam Z-scan technique with Ar+ and Ne–He lasers. The largest reported effective nonlinear coefficient, n 2 =−8.07×10 −7 cm 2 / W , was obtained. It is demonstrated that the nonlinear optical response originals from quantum confinement effect.
47 citations
TL;DR: In this paper, the effect of Cr doping on structural, morphological and optical properties of nanoparticles was investigated by using energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and UV-visible spectroscopy.
Abstract: Nanoparticles of Zn1−xCrxS (x=0.00, 0.005, 0.01, 0.02 and 0.03) were prepared by a chemical co-precipitation reaction from homogenous solutions of zinc and chromium salts. These nanoparticles were sterically stabilized using 2-mercaptoethanol. Here a study of the effect of Cr doping on structural, morphological and optical properties of nanoparticles was undertaken. Elemental analysis, morphological, structural and optical properties have been investigated by energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–visible spectroscopy .EDAX measurements confirmed the presence of Cr in the ZnS lattice. XRD showed that ZnS:Cr nanoparticles crystallized in zincblende structure with preferential orientation along (1 1 1) plane. The average sizes of the nanoparticles lay in the range of 3–6 nm and lattice parameters were in the range of 5.2–5.4 A. Lattice contraction was observed with an increase of Cr concentration. The particle size and lattice parameters obtained from TEM and SAED images were in agreement with the XRD results. The absorption edge shifted to lower wavelengths with an increase in Cr concentration as per UV–Vis spectroscopy. The band gap energy values were in the range of 3.85–4.05 eV. This blueshift is attributed to the quantum confinement effect.
47 citations