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Ma X.,China Agricultural University | Ma X.,Yunnan Normal University | Liu Z.-M.,Yunnan Normal University | Qu S.,Eoplly New Energy Technology Co. | And 3 more authors.
Chinese Physics Letters

A new method to measure trap characteristics in crystalline silicon solar cells is presented. Important parameters of traps including energy level, total concentration of trapping centers and capture cross-section ratio of hole to electron are deduced using the Shockley - Read - Hall theory of crystalline silicon solar cells in base region. Based on the as-deduced model, these important parameters of traps are determined by measuring open-circuit voltages of silicon solar cells under monochromatic illumination in the wavelength range 500-1050 nm with and without bias light. The effects of wavelength and intensity of bias light on the measurement results are also discussed. The measurement system used in our experiments is very similar to a quantum efficiency test system which is commercially available. Therefore, our method is very convenient and valuable for detecting deep level traps in crystalline silicon solar cells. © 2011 Chinese Physical Society and IOP Publishing Ltd. Source

Wang W.,Nanjing University of Aeronautics and Astronautics | Shen H.-L.,Nanjing University of Aeronautics and Astronautics | Jin J.-L.,Nanjing University of Aeronautics and Astronautics | Li J.-Z.,Nanjing University of Aeronautics and Astronautics | Ma Y.,Eoplly New Energy Technology Co.
Chinese Physics B

Zn/Sn/Cu (CZT) stacks were prepared by RF magnetron sputtering. The stacks were pretreated at different temperatures (200 °C, 300 °C, 350 °C, and 400 °C) for 0.5 h and then followed by sulfurization at 500 °C for 2 h. Then, the structures, morphologies, and optical properties of the as-obtained Cu2ZnSnS4 (CZTS) films were studied by x-ray diffraction (XRD), Raman spectroscopy, UV-Vis-NIR, scanning electron microscope (SEM), and energy-dispersive x-ray spectroscopy (EDX). The XRD and Raman spectroscopy results indicated that the sample pretreated at 350 °C had no secondary phase and good crystallization. At the same time, SEM confirmed that it had large and dense grains. According to the UV-Vis-NIR spectrum, the sample had an absorption coefficient larger than 104 cm-1 in the visible light range and a band gap close to 1.5 eV. © 2015 Chinese Physical Society and IOP Publishing Ltd. Source

Shi M.,Soochow University of China | Yang J.,Soochow University of China | Yang J.,Eoplly New Energy Technology Co. | Li Z.,Harbin Institute of Technology | And 3 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams

A novel single-shot method for the investigation of surface nonlinearity in materials with limited transparency is demonstrated. When a circular disk that blocks the beam is placed in the beam path before the detector in the conventional reflection 4F coherent imaging system, the surface nonlinear optical response of the sample can be determined by measuring the normalized reflectance under different conditions. The theoretical principle of the method is presented in detail and the influences of incidence-angle variation on the measurement sensitivity are analyzed using numerical simulation. This approach allows for sensitivity enhancement, one-laser-shot detection, determination of the nonlinear absorption coefficient and nonlinear refractive index simultaneously. The results show that the measurement sensitivity of this novel technique is two orders of magnitude larger than that of the original reflection Z-scan technique under the same condition. Source

Jia X.,CAS Institute of Electrical Engineering | Zhou C.,CAS Institute of Electrical Engineering | Tang Y.,Eoplly New Energy Technology Co. | Wang W.,CAS Institute of Electrical Engineering
2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015

The SiOx(C)/SiNx dual-layer shows a better anti-reflection coating compared with standard SiNx films, after deposition and annealing. In this paper, the effect of film thickness, sintering peak temperature, belt speed, etc. on the anti- reflectance of SiOx(C) film were discussed. Under optimized condition, the weighted reflectance of SiOx(C)/SiNx dual-layer obtained 1.25% reduction; the efficiency of solar cell rises 0.35%. Sixty solar cells with dual-layer encapsulated modules gained 0.5 W larger power as well as better light stability than the ones with SiNx single layer. © 2015 IEEE. Source

Gao Y.,CAS Institute of Semiconductors | Zhang X.W.,CAS Institute of Semiconductors | Yin Z.G.,CAS Institute of Semiconductors | Si F.T.,CAS Institute of Semiconductors | And 5 more authors.
Journal of Applied Physics

FePt nanoparticles were self-assembled on a MgO (001) substrate by a micellar method. We introduced an Au buffer layer to control the lattice orientation and the magnetic alignment of FePt nanoparticles. A distinct c-axis preferred orientation of the FePt nanoparticles was achieved during the thermal annealing treatment. The driving force of lattice reorientation is considered to be the result of the stress caused by the lattice misfit between Au and FePt. The degree of c-axis orientation is significantly enhanced with increasing Au thickness, which is attributed to the decrease of the in-plane lattice and the improved crystal quality of the Au layer. Perpendicular magnetic anisotropy was observed for the FePt samples with the Au buffer layer. The out-of-plane coercivity and remanence ratio are 3.1 kOe and 0.8, respectively, which far exceed the in-plane values. © 2011 American Institute of Physics. Source

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