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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: A wide bandgap and highly conductive p-type hydrogenated nanocrystalline silicon (nc-Si:H) window layer was prepared with a conventional RF-PECVD system under large H dilution condition, moderate power density, high pressure and low substrate temperature.
Abstract: A wide bandgap and highly conductive p-type hydrogenated nanocrystalline silicon (nc-Si:H) window layer was prepared with a conventional RF-PECVD system under large H dilution condition, moderate power density, high pressure and low substrate temperature. The optoelectrical and structural properties of this novel material have been investigated by Raman and UV-VIS transmission spectroscopy measurements indicating that these films are composed of nanocrystallites embedded in amorphous SiHx matrix and with a widened bandgap. The observed downshift of the optical phonon Raman spectra (514.4 cm(-1)) from crystalline Si peak (521 cm(-1)) and the widening of the bandgap indicate a quantum confinement effect from the Si nanocrystallites. By using this kind of p-layer, a-Si:H solar cells on bare stainless steel foil in nip sequence have been successfully prepared with a V c of 0.90 V, a fill factor of 0.70 and an efficiency of 9.0%, respectively. (c) 2006 Elsevier B.V. All rights reserved.
40 citations
TL;DR: In this article, the voids in artificial opal latex are filled with nanosized TiO2 particles by adding a drop of TiCl4 into the latex matrix, hydrolyzing, and heating.
Abstract: Inverse opal TiO2 may offer a novel and promising solution for enhancing the light harvesting efficiency of dye-sensitized solar cells (DSSCs). Its large interconnected pores enable a better penetration of the dye sensitizers via the matrix pores, making this material surpasses the efficiency of conventional TiO2 electrodes. Moreover, it also exhibits a photonic band gap that may enable a significant change in its dye absorbance by the adjustment of the photon localization near the red edge of the photonic band gap to the position of dye absorption. In this study, we report a simple method of fabrication of inverse opal TiO2, wherein the voids in artificial opal latex are filled with nanosized TiO2 particles by adding a drop of TiCl4 into the latex matrix, hydrolyzing, and heating. In this process, we investigate the effect of different heat treatment times on the properties of inverse opal TiO2. Photoacoustic (PA) characterization shows that longer heat treatment times could produce more defect sites. The presence of defects causes the inhibition of electron transfer and results in a decrease in incident photon-to-current conversion efficiency (IPCE). CdSe quantum dots were adsorbed onto inverse opal TiO2 by chemical deposition. The blue shift of PA spectra relative to the bulk CdSe and the gain in IPCE were clearly observed. This result indicates the quantum confinement effect and photosensitization of CdSe quantum dots.
40 citations
TL;DR: In this article, a one-step corrosion process was reported to synthesize nanostructured CuO thin films at room temperature, where the reaction time has great effect on the composition and microstructure of products to control the size and shape of the copper compound.
Abstract: We report a one-step corrosion process to synthesize nanostructured CuO thin films at room temperature. The reaction time has great effect on the composition and microstructure of products to control the size and shape of the copper compound. X-ray diffraction studies showed the transformation of nanograins from Cu(OH)2 nanowires to flower-like CuO and to dispersed CuO nanosheets. The optical properties of CuO nanosheets were investigated by using UV-vis spectroscopy with considerable blue-shift in the optical band gap (Eg = 1.8 eV) due to the quantum confinement effect. Additionally, the photocatalytic activities of as-prepared copper compound films were determined by measuring the degradation of methyl blue (MB) to find out their potential application in waste water treatment. The photoluminescence (PL) spectrum showed both UV as well as visible emission peaks, indicating their good optical properties. Moreover, a reasonable growth mechanism for the formation of the CuO nanostructure is proposed by means of a scanning electron microscope (FESEM).
39 citations
TL;DR: In this paper, the authors investigated the carrier-phonon relaxation process in 2D halide perovskites with the general formula of (BA)2(MA)n-1PbnI3n+1, where n = 2, 3, and 4, by femtosecond transient absorption spectroscopy.
Abstract: We thoroughly investigated the carrier-phonon relaxation process in 2D halide perovskites with the general formula of (BA)2(MA)n-1PbnI3n+1, where n = 2, 3, and 4, by femtosecond transient absorption spectroscopy. A significant enhancement of the hot phonon bottleneck effect is observed in the natural multiple quantum well with n = 2 and 3. Specifically, the sample with n = 3 shows a 1000 ps hot carrier relaxation time to reach room temperature, which is 10 times longer compared with its three-dimensional counterpart. We believe that both the organic cation and quantum confinement effect are responsible for this phenomenon. The acoustic phonon cannot propagate due to the decrease in group velocity caused by the confinement effect in such a quantum well structure. In addition, the confined acoustic phonons can up-convert to optical phonons due to the presence of a “hybrid phonon” induced by the organic cation. This result suggests a promising way to obtain long-live hot carrier materials.
39 citations
TL;DR: In this article, the authors reported QCE in all-inorganic halide perovskite in two-dimensional (2D) nanoplates and showed that the exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence, while the function of integrated intensity and full width at half maximum and temperature also showed similar results.
Abstract: Quantum confinement effect (QCE), an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking CsPbBr3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional (2D) nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below ~7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.
39 citations