Synthesis and luminescence properties of CaNb2O6 oxides by the sol-gel process were investigated. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ...high-resolution transmission electron microscopy (HRTEM), photoluminescence spectroscopy and absorption spectra. The PL spectra excited at 257 nm have a broad and strong blue emission band maximum at 457 nm, corresponding to the self-activated luminescence of the niobate octahedra group NbO67-. The optical absorption spectra of the 700 deg C sample exhibited the band-gap energies of 3.53 eV.
We have used 1.5wt.% of nanodiamonds having three different sizes such as 5, 50 and 250nm for making the hybrid active layer. As the nanodiamond size increased, the root mean square (rms) roughness ...also increased in the film. The film with nanodiamond has a higher absorption intensity than the P3HT:PCBM film. The power conversion efficiency (PCE) of the device has improved from 1.8% to 2.4%, as a result of increased current density for P3HT:PCBM mixed with nanodiamond having 50nm.
► A novel technology for preparing hybrid diamond organic films is presented. ► The hybrid light-activated P3HT/PCBM/ nanodiamond is performed. ► A highly absorption with high hybrid nanodiamonds of 50nm is achieved. ► Enhancing current density of photovoltaic device are obtained.
Silicon nanowire (SiNW) arrays were grown directly on a P type Si substrate, pre-deposited with gold catalyst, and then made into solar cell for photovoltaic characteristic measurement. Different ...growth conditions of SiNWs, including variation of the flow rate ratio of SiH
4 versus N
2, and the thickness of Au film, which can be sputtered into different size of nanoparticles, will be made in order to obtain an optimum photovoltaic conversion efficiency. The morphologies and crystalline structure of the nanowires are studied by SEM, TEM and XRD. The SiNW array surface is shown to have good antireflection property, and is expected to raise light absorption and short circuit current. The photovoltaic performance of the solar cells with SiNWs grown at different conditions is measured and discussed. More effort is still needed to raise the performance of SiNW solar cells.
We investigate the performance of amorphous Si (a-Si) solar cells fabricated with Inductively Coupled Plasma (ICP) deposition technique. The ICP system produces a-Si films with low defect density ...(3×1015cm−3), resulting in a conversion efficiency of 9.6%. Deep level transient spectroscopy (DLTS) reveals that hole carriers trapped at defects near the valence band edge delocalize at 130K; while trapped electrons can only be emitted into the conduction band near room temperature. Spectrally resolved DLTS study further indicates that light soaking enhances the emission rate of the tapped electrons near the conduction band edge while reduces the transition moments from the hole-trapping defect levels to the conduction band. The combined effects and light soaking-induced defects are responsible for the degradation of a thin film solar cell by light soaking.
► ICP CVD thin-film solar cells have low defect density and high conversion efficiency. ► The carrier transport is mainly limited by the carrier-trapping defects near the band edges. ► The Si framework of ICP CVD films is stable and can endure prolonged light soaking. ► Light soaking reduces the optical transition moments and increases the emission rate of tapped electrons.
We synthesized a loosely packed submicrometer silica-sphere (LPSS) monolayer at room temperature and used the LPSS monolayer as the frontside light-trapping structure for n-i-p-type amorphous Si ...(a-Si) solar cells (SCs) to improve photovoltaic characteristics of the cells. The frontside LPSS monolayer plays a role as a UV-visible light scatter and a broadband antireflector; both can greatly improve the photoresponse of the underneath a-Si adsorbed layer. When the filling density of the LPSS layer is optimized to 65%, the enhancement in the photocurrent and conversion efficiency of the 120 ° C -fabricated SCs is as high as ~ 15% and ~ 6.9%, respectively. Accordingly, such an LPSS light-trapping structure boosts efficiency of 120 ° C - and 140 ° C-fabricated cells to 7.3% and 8.5%, respectively. Since the LPSS structure has a graded refractive index profile, it behaves like a nearly omnidirectional antireflector, enhancing solar efficiency at a very large incident angle of illumination.
The growth of ZnO nanowires (NWs) on a zinc oxide (ZnO)/textured crystalline-Si (c-Si) photovoltaic device via the hydrothermal method is investigated. The average length and diameter of the ZnO NWs ...are around 0.65μm and 70–100nm, respectively. Experimental results indicate that a ZnO/textured c-Si photovoltaic device with ZnO NWs has the lowest reflectance among the tested substrates, especially in the range of ultraviolet (UV) and green light (350nm to 590nm). Compared to SiNx/textured c-Si and ZnO/textured c-Si photovoltaic devices, the proposed device exhibits photovoltaic conversion efficiency improvements of around 7% and 6.3%, respectively. After encapsulation, the ZnO NWs/ZnO/textured c-Si photovoltaic device has the lowest drop in conversion efficiency. Furthermore, a small NW diameter increases light absorption.
In the present work, a micro-thruster chip with dimension of 19.5
mm
×
9.5
mm was fabricated with MEMS technologies for the experiment study of vaporizing liquid micro-thruster. In addition, a full ...3D computational model was constructed to simulate the aft section of a vaporizing liquid micro-thruster for investigating flow characteristics. The results show that there were four distinct flow patterns observed in this study including snake flow, vapor-droplet flow, vapor-droplet-jet flow, and vapor flow. To prevent the failure of micro-thruster chip from generating of snake flow, the heating treatment of an empty micro-thruster chip at 300
°C for 2
h was the key factor. The generation of vapor flow preliminarily proved that the concept of vaporizing liquid micro-thruster chip was feasible. Furthermore, the numerical model in this study successfully provided the thrust estimation. The channel cross-section of 1
mm
×
100
μm designed in this study was fit for developing a micro-thruster of O(mN) (ranging from 1 to 6
mN approximately). The numerical simulation could match better with the experiment results for the vapor flow cases if the flow oscillation was taken into consideration, and the heating channel of micro-thruster was lengthened to completely vaporize the liquid water.
This study reports the deposition of cuprous oxide Cu
2
O onto titanium dioxide TiO
2
nanowires NWs prepared on TiO
2
/glass templates. The average length and average diameter of these thermally ...oxidized and evaporated TiO
2
NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu
2
O fills gaps between the TiO
2
NWs with good step coverage to form nanoshells surrounding the TiO
2
cores. The p-Cu
2
O/n-TiO
2
NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu
2
O-shell/n-TiO
2
-nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses.
Si nanowire (NW)-based photovoltaic devices were fabricated using NWs grown at various temperatures. It was found that the average length and average diameter of the NWs increased as the growth ...temperature was increased from 450°C to 620°C. It was also found that the NWs became sparser with increasing growth temperature. The reflectance spectra and I-V characteristics indicate that the average reflectances were about 9%, 15%, and 18% and that the photovoltaic conversion efficiencies were 4.1%, 2.33%, and 1.87% for Si NWs grown at 450°C, 550°C, and 620°C, respectively. The experiment results show that the largest fill factor (74%) and external quantum efficiency (40%) (for a wavelength of 740 nm) were achieved for Si NWs grown at 450°C.
In this study, an efficient approach for the removal of colloidal silica abrasives from the polished copper surface was proposed and demonstrated. This post-chemical mechanical polishing (CMP) ...cleaning process combines a buffing process with dilute HNO
3/benzotriazole (BTA) aqueous solution for copper surface passivation and a polyvinyl alcohol (PVA) brush scrubbing process with wetting surfactants, Triton X-100, for colloidal silica removal. Buffing with HNO
3/BTA aqueous solution was able to remove copper oxide and form the Cu(I)–BTA hydrophobic passivation. Scrubbing with Triton X-100 surfactant is to enhance the wettability on Cu(I)–BTA surface for the removal of residual silica abrasives. The wetting ability of Triton X-100 was determined by a contact angle and surface tension measurements. It was demonstrated that silica abrasives could be removed efficiently without copper corrosion by this cleaning process.
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