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Li Y.,North China Electrical Power University | Li M.,North China Electrical Power University | Li M.,Chongqing Instrument Materials Research Institute | Li R.,North China Electrical Power University | And 3 more authors.
Applied Physics Letters | Year: 2015

The length of the silicon nanowire (SiNW) is a key parameter in photovoltaic devices, as it dramatically decides the light-harvesting and carrier recombination. Here, we develop a method to determine the optimal SiNW length for photovoltaic devices, by comparing the light-harvesting efficiency of SiNWs with various lengths. The light-harvesting efficiency is measured by the light intensity in the SiNW, and the fraction of the length with high light intensity in its whole length. Under these criteria, we find that the optimal SiNW length is around 3 μm. This method is helpful in further optimization and application of SiNW-based solar cells. © 2015 AIP Publishing LLC. Source

Li Y.,North China Electrical Power University | Yue L.,China University of Petroleum - Beijing | Luo Y.,North China Electrical Power University | Liu W.,North China Electrical Power University | And 2 more authors.
Optics Express | Year: 2016

Silicon nanostructures have light-harvesting effects for enhancing the performance of solar cells. Based on theoretical investigations on the optical properties of silicon nanowire (Si NW), the influencing laws of the size of Si NW on its light-harvesting effect are proposed. For the first time, we reveal that the resonant wavelength of Si NW predicted by the leaky mode theory does not correspond to the actual resonant wavelength calculated by the discrete dipole approximation method, but exactly coincides with the leftmost wavelength of the resonance peak. Then, the size dependency of the resonant intensity and width of Si NW is different from that of spherical nanoparticles, which can be deduced from the Mie theory. The size dependencies of resonant intensity and width are also applicative for silver/silicon composite nanowires. In addition, it is found that the harvested light by the Si and Ag/Si NW both show significant radial locality feature. The insight in this work is fundamental for the design and fabrication of efficient light - harvesting nanostructures for photovoltaic devices. ©2016 Optical Society of America. Source

Song D.,North China Electrical Power University | Cui P.,North China Electrical Power University | Wang T.,North China Electrical Power University | Wei D.,North China Electrical Power University | And 10 more authors.
Journal of Physical Chemistry C | Year: 2015

The carrier lifetime and the doping property of the lead halide perovskites are essential factors determining their application in solar cells. Hence, these two factors of the perovskite (CH3NH3PbI3) film were managed by postannealing, and the underlying mechanisms governing their effects on the photovoltaic performance of the solar cells were investigated. The short carrier lifetime from electron-hole bimolecular recombination, corresponding to the fast decay of photoluminescence, is achieved in perovskite films annealed at high temperatures. The doping property of the perovskite varies from p-type, intrinsic to n-type with increasing annealing temperature. The short carrier lifetime and the intrinsic feature of the perovskite benefit for high open circuit voltage of the corresponding solar cells, whereas the n-type doped perovskite leads to the high photocurrent and efficiency. Through the management of the carrier lifetime and the doping property, highly efficient perovskite solar cells with conversion efficiency over 17% were prepared. These results provide new insights into the underlying relations between the perovskite properties and the device performance. © 2015 American Chemical Society. Source

Tao Y.-B.,Kunming University of Science and Technology | Tian H.,Chongqing Instrument Materials Research Institute | Yang C.-Z.,Kunming University of Science and Technology | Lin H.,Nanjing University of Science and Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

In terms of the inadequacy of the traditional Boost-type PFC power switching devices which brings a lot of switching losses and conduction losses, and burdens with a high voltage, strong current and thermal stress, this paper proposes a new Bridgeless Topology Active Power Factor Correction (BLPFC) circuit construction. This circuit changes the two diodes in traditional rectifying bridge legs into IGBT, and adopts dual closed-loop average current control strategy to improve power factor and reduce the harmonic pollution from the grid. It can improve the system switching devices efficiently and reduce system heat dissipation and costs. This circuit is simulated using the SimPowerSystems kit in Matlab/Simulink software. Simulation results show that BLPFC provides a high efficiency, low switching losses, and can restrain current harmonics, and the input current which can keep track of the input voltage waveform well. Source

Shen J.,Chongqing University | Peng C.,Chongqing University | Yin H.G.,Chongqing University | Chen J.,Chongqing University | Chen J.,Chongqing Instrument Materials Research Institute
Journal of Materials Science: Materials in Electronics | Year: 2012

The influence of minor POSS (polyhedral oligomeric silsesquioxanes) molecules additions on the microstructure and hardness of SnAgCu-xPOSS (x = 1, 3 and 5) was investigated. A mechanical mixture method was adopted by adding POSS molecules as dispersoids into SnAgCu solder to fabricate SnAgCu-xPOSS composite solders. The microstructural evolution and the hardness of the solders were investigated in details by microstructural observations, Vickers hardness tester and nanoindentation tests. The results showed that the effects of the dispersed POSS molecules in eutectic SnAgCu structure and the refined Ag 3Sn IMC particles increased the hardness of eutectic SnAgCu phase and then increased the hardness of composite solder. In addition, because of the agglomeration of POSS molecule, a coarse lath-shaped structure (composed of POSS molecules, Ag 3Sn phase and minor Cu 6Sn 5 phase) formed in SnAgCu-5POSS solder matrix, which reduced the hardness of SnAgCu-5POSS solder. © Springer Science+Business Media, LLC 2012. Source

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