Improving the efficiency of c-Si solar cells through the optimization of emitter profile and low resistance ohmic metal contact

Recently, efforts in improving the efficiency of monocrystalline silicon (c-Si) solar cells are focused on optimizing the emitter profile and the metallization which reduces the recombination losses, the contact resistances and improve the collection probability of carriers. The emitter recombination is reduced with decreasing the well passivated emitter thickness and lowering the doping concentration whereas it increases the metal-semiconductor contact resistance and thus reducing the fill factor (FF). In this paper, the metal-semiconductor ohmic contact formation, the emitter optimization, the co-relation with ohmic contact, and the optimum metallization pattern are investigated. The emitter saturation current density (J(oe)), the carrier life time (tau(eff)), the internal quantum efficiency (IQE), the series resistance (R-s), the short circuit current (I-sc), the open circuit voltage (V-oc), the fill factor (FF) and the cell efficiency are analyzed for different emitter profiles and compared with the standard process. A batch of 156 pseudo mm square mono c-Si solar cells with average cell efficiency of17.5% is observed at 72-75 Omega/square sheet resistance. (C) 2012 Elsevier B. V ... Selection and peer-review under responsibility of Bin Nusantara University