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Zhou C.,CAS Institute of Electrical Engineering | Zhou S.,CAS Institute of Electrical Engineering | Wang W.,CAS Institute of Electrical Engineering | Zhao L.,CAS Institute of Electrical Engineering | And 5 more authors.
Conference Record of the IEEE Photovoltaic Specialists Conference

The emitter dopant profile between the metal grid in lase doping selective emitter cells was modified by oxidation the phosphosilicate glass (PSG) film at a higher temperature. This diffusion process contains two steps. Step 1 form the PSG layer on the wafer surface by the reaction of POCl3 and oxygen. Step 2 increase the temperature to a higher value at which the oxidation of PSG layer is proceeded. For the practical cell process, the laser power and front metal-grid were optimized, considering the dependence on the light induced plating nickel-silicon contact and on the emitter sheet resistance. Comparing with the uniform emitter multicrystalline silicon solar cells, significant increase of short circuit current by 0.3 A and open circuit voltage by 6 mV was obtained resulting in an average gain of 0.6%abs. An average efficiency of 17.2% and the largest of 17.42% for the best cell on a large area commercial grade p-type multi-crystalline silicon substrate were achieved. © 2012 IEEE. Source

Li T.,CAS Institute of Electrical Engineering | Wang W.,CAS Institute of Electrical Engineering | Zhou C.,CAS Institute of Electrical Engineering | Song Y.,Chinalight Solar Co. | And 2 more authors.
Progress in Photovoltaics: Research and Applications

Large-area multicrystalline silicon solar cells fabrication by laser doping is studied in this paper. The liquid dopant solution is sprayed onto the SiNx:H film to act as dopant source. Laser doping is performed to locally melt silicon substrates, and phosphorus dopant atoms are incorporated into the liquid silicon by liquid-phase diffusion to form a selective emitter. Light-induced plating is carried out for front side metallization. The influences of laser energy density and pulse overlap on electrical performance of large-area multicrystalline silicon solar cells are obtained. The laser energy density and pulse overlap are optimized in consideration of sufficient built-in voltage and small-scale laser-induced damage. The typical spectral response for large-area multicrystalline silicon solar cells by laser doping is presented. The typical efficiency distribution for 1-day production of the 10 MW production line shows the overall average efficiency above 18% on large-area commercial-grade multicrystalline silicon substrates for the 4 months of operation, confirming the potential for transferring high-efficiency selective emitter silicon solar cells by laser doping into a production line. Copyright © 2012 John Wiley & Sons, Ltd. Source

Li T.,CAS Institute of Electrical Engineering | Zhou C.-L.,CAS Institute of Electrical Engineering | Song Y.,Chinalight Solar Co. | Yang H.-F.,Chinese Academy of Inspection and Quarantine | And 5 more authors.
Wuli Xuebao/Acta Physica Sinica

One main factor of restricting industrial crystalline solar cell efficiency is the optical losses caused by the metal front side contacts, including the absorption loss and reflection loss. Based on screen-printed and screen-printed seed layers thickened by light-induced electroplating solar cells, in this paper various cases of optical losses due to the metal contacts are analyzed. Taking into account the reflections in the air-glass interface and the edge regions of metal contacts, the optical losses are simulated by assuming approximately half-oval cross-section of metal contacts. The results show that the effective width ratio is about 40% of the metal contact geometry width. By measuring and calculating the reflection spectra of different types of samples, the optical losses of the metal front side contacts of solar cells are obtained in theoretical simulation and experimental measurement. The corresponding theory and the experimental results are in good agreement with each other. © 2011 Chinese Physical Society. Source

Li T.,CAS Institute of Electrical Engineering | Zhou C.,CAS Institute of Electrical Engineering | Song Y.,Chinalight Solar Co. | Zhang L.,Guangzhou Cookson Enthone Trading Company Ltd | And 10 more authors.
Acta Chimica Sinica

Self-aligned light-induced electroless plating/electro-plating technology, with its advantages of fine grid lines and fast and efficient process, became an ideal option for the preparation of selective emitter solar cells. However, before these technologies processing, the heavy doping area should be etched by HF solution to remove the surface SiO2 effectively and the pinholes should not emerge to expose the silicon substrate in the SiNx:H mask. Otherwise, the metal nickel and silver would deposit in the pinholes during the light-induced electroless plating/electro-plating resulting in the over-plating phenomenon. This demanded that the pretreatment solution should have highly selective etching for SiO2/SiNx:H. This paper analyzed the causes of the over-plating phenomenon in terms of the experiment results and studied the feasibility of selective etching for SiO2/SiNx:H. According to the mechanism of HF etching SiO2 and SiNx:H, the over-plating phenomenon of multicrystalline silicon solar cells was improved by adjusting the pH value of the buffer HF solution. Source

Li T.,CAS Institute of Electrical Engineering | Zhou C.,CAS Institute of Electrical Engineering | Song Y.,Chinalight Solar Co. | Gao Z.,Chinalight Solar Co. | And 3 more authors.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica

The theoretical model of continuous laser ablation of monocrystalline silicon solar cells using thermodynamic method was established and analytical solution by calculating the temperature field distribution of a simplified model was obtained. According to the highly nonlinear of model of laser ablating monocrystalline silicon, the unsteady temperature field distribution and ablation depth, ablation width as well as ablation morphology were simulated using the finite difference method in Matlab within appropriate time. The simulation results are consistent with the experimental observations. Source

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