Papers by Keyword: Solar Cell

Abstract: Silicon nanocrystals (Si NCs) are a promising candidate for the top cell of an all-Si tandem solar cell with a band gap from 1.3-1.7 eV, tuneable by adjusting NC size. They are readily produced within a Si-based dielectric matrix by precipitation from the Si excess in multilayers of alternating stoichiometric and silicon-rich layers. Here we examined the luminescence and transport of Si NCs embedded in SiC. We observed luminescence that redshifts from 2.0 to 1.5 eV with increasing nominal NC size. Upon further investigation, we found that this redshift is to a large extent due to Fabry-Pérot interference. Correction for this effect allows an analysis of the spectrum emitted from within the sample. We also produced p-i-n solar cells and found that the observed I-V curves under illumination could be well-fitted by typical thin-film solar cell models including finite series and parallel resistances, and a voltage-dependent current collection function. A minority carrier mobility-lifetime product on the order of 10^-10 cm²/V was deduced, and a maximum open-circuit voltage of 370 mV achieved.

Abstract: Titania (or titanium dioxide) nanotubes are advanced materials with diverse functionalities. They have a variety of applications ranging from biology, food, cosmetics, energy and related areas. In this paper, we provide a brief description of electrochemical routes that may be used to synthesize such nanotubes rapidly over large areas. We also provide a brief overview of their energy-related.

Abstract: The layered double hydrotalcites (LDH) with molar ratio Zn:Al=2:1 was prepared by urea method. The mixed oxides were prepared by calcining the LDH at different temperatures and a series of dye-sensitized solar cells were assembled by the corresponding oxides and the dye Ruthenizer 535-bisTBA (N719). The basic parameters were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric and differential thermal analysis (TG-DTA) and UV-Vis absorption spectrum. The photovoltaic behaviors of solar cells were characterized and the best efficiency was 0.015% when the calcining temperature was 500°C.

Abstract: Photonic crystals have been widely applied to improve the efficiency of solar cells due to its capability to manipulate photon transmission. Both theoretical and experimental research have shown that photonic crystals can significantly improve the absorption and conversion efficiency of solar cells.Solar cells that have photonic crystals back reflectors, intermediate reflectors, and window layers have higher photoelectric conversion efficiency. In this paper, the state-of-the-art applications of PCs in solar cells are summarized. Various fabrication methods for photonic crystals and their associated performance are discussed.

Abstract: Composition of an AlGaAs/GaAs/Ge triple-junction solar cell were analyzed using an equivalent circuit. The currentvoltage (IV) characteristics and impedance spectroscopy (IS) of it were measured in the temperature range from 20°C to 180°C. In the high-temperature range (from 140°C to 200°C) the V_OC changes faster than those in the low-temperature range (from 20°C to 80°C).This is because contribution of the V_OC from the Ge subcell becomes nearly zero in the high temperature. R and C of the bottom subcell keep almost the same in the high temperature.

Abstract: Nanostructure strategies are frequently used to enhance the light absorption in solar cells. For improving the efficiency of absorption in solar cells, an industrial-feasible processing technique, i.e. low-pressure chemical vapor deposition was used to form a substrate with large-area silicon nanoparticles (Si-NPs). It was shown that the density and size of Si-NPs can be modulated by controlling the flow of pure SiH4, the deposition temperature and the deposition time. The substrate with large-area Si-NPs can be applied in photovoltaic devices since they can increase the effective absorption path of the incident sunlight.

Abstract: We have investigated an effect of N incorporation on InGaAsN on Ge (001), which is proposed to be a part of the InGaP(N)/InGaAs/InGaAsN/Ge four-junction solar cell, and on its growth behavior. Results obtained from high resolution X-ray diffraction and Raman scattering demonstrated that high quality In_0.11Ga_0.89As_1-yN_y films with N (y) contents up to 5% were successfully grown on n-type doped Ge (001) substrate by metalorganic vapor phase epitaxy using low-temperature (500°C) GaAs buffer layer. As expectation, the In_0.11Ga_0.89As_0.96N_0.04 film is examined to be under lattice-matching condition. Anti-phase domains were observed for the film without N incorporation, which exhibits submicron-size domains oriented along the [110] direction on the grown surface. With increasing N content, the domains become less orientation, and present in a larger domain size. Based on results of transmission electron microscopy, a high density of anti-phase domains was clearly observed at the interface of low-temperature GaAs buffer layer and Ge substrate. On the other hand, it is found to drastically reduce within the N-contained InGaAsN region. Furthermore, the lattice-matched In_0.11Ga_0.89As_0.96N_0.04 film is well developed to reduce the density of anti-phase domains.

Abstract: The high-quality two sizes CdSe quantum dots (QDs) with nearly monodisperse size and shape were synthesized by the employed hot injection method with some modifications. The nanoparticles diameters were to be 2.6nm and 3.0nm respectively. To improve crystallization property and specific surface area of TiO₂ and to inhibit recombination processes of photoinduced electrons effectively, TiO₂-nano-SiO₂ hybrid films were prepared by adding proper meso-porous SiO₂ into TiO₂, in which the mass ratio of SiO₂ to TiO₂ was 5%. CdSe QDs were linked to TiO₂-nano-SiO₂ films using 3-mercaptopropionic acid to increase CdSe QDs adsorption. Two sizes CdSe QDs were achieved both to promote charge separation and to ensure the porper mobile pathway of free carriers. The J-V characterization showed that two sizes CdSe QDs co-sensitized TiO₂-nano-SiO₂ hybrid photoelectrodes had higher short circuit current density (J_SC) and open circuit voltage (V_OC), compared to one size CdSe QDs.

Abstract: In this paper we reported on fabrication and characterization of a composite harvesting device integrated thin-film rechargeable battery on α-Si thin-film solar cell. The α-Si thin-film solar cell typically presented open-circuit voltage of 4.3 V, short-circuit current of 15.4 mA/cm² and efficiency of 7.4%. The thin-film rechargeable battery composed of Nb₂O₅/LiPON/LiMn₂O₄ systems fabricated using dry process, which showed the initial discharge capacity of about 215 μAh (or 12.4 μAh/cm²), the cycleabilty for discharge was good at keeping about 12.3 μAh/cm² with a small decreasing ratio of 0.1% per cycle and the coulombic efficiency was all over 95% for the 100 cycles. On the other hand, the discharge capacity of approximately 80% was provided by the self-charging of the solar cell for 10 min, and the coulombic efficiency was also over 95%.

Abstract: The J-V curve measurment and AFM technology were applied to study the relationship between P3HT:PCBM heterojunction film solar cell devices photovoltics parameter and blend solution concentration and annealed time of this device. The Voc, Jsc, FF and PCE of device were obtained from the device prepared by three blend solution concentration respectively. Data show that with increasing solution concentration PCE of solar cell device do not always improve and it achieves maximum when concentration is 20 mg/mL. Result indicates that only when solar cell device has active layer with proper thickness its performance will achieve the best effect. Additionally, photovoltaic parameters from four sample prepared by different annealed time were obtained also. Results indicate that the device with proper annealed time of 20 min at 130°C can achieve the best effect.