Silicon solar cells using low cost TiO2 thin layers prepared by chemical spray pyrolysis

Silicon, crystalline and multi-crystalline, continues being an important material for photovoltaic module production. Increased volumes of fabrication have allowed the reduction of costs but not yet to the levels that makes photovoltaic energy competitive with conventional electricity generation in large scale applications. Henceforth, a further reduction cost is needed for making this kind of solar cells. In this work, we explain the steps developed in our laboratories for making low cost silicon solar cells using TiO₂ as anti-reflection layer obtained by spray pyrolysis. In addition, this layer also allows the grid contact definition for "electroless" nickel deposition, but it does not provide enough surface passivation. In order to achieve the latter, a thin layer of SiO₂ was inserted between the silicon surface and the TiO₂ layer. Even better results were achieved when a silicon oxynitride (SiON) is used instead of SiO₂. When the intermediate SiON layer is used, both the open circuit voltage and the short circuit current density are improved as compared to the reference cells (those without any surface passivation). We are now in the process of optimizing this new kind of solar cells.