Method of producing photovoltaic element

DETAILED DESCRIPTION In view of the above-described problems, an object of the present invention is to provide a method of producing a photovoltaic element, more particularly a thin-film solar cell having good characteristics and producible in a high yield, which method ensures that in a case where a shunt portion of the photovoltaic element in which a back surface reflecting layer, a semiconductor layer and a transparent electrode layer are successively stacked on a substrate is removed by an electrolytic treatment in such a manner that the photovoltaic element is immersed in an electrolytic solution and a forward voltage is applied to the photovoltaic element to cause a reduction reaction on the transparent electrode layer in the defective portion, the shunt portion can selectively be removed with reliability without causing breakdown of any portion other than the shunt portion and without increasing the shunt path.
To achieve the above-described object, according to the present invention, there is provided a method of producing a photovoltaic element comprising the steps of immersing in an electrolytic solution a photovoltaic element comprising a back surface reflecting layer, a semiconductor layer and a transparent electrode layer successively stacked on a substrate, applying a forward voltage to the photovoltaic element to effect an electrolytic treatment to reduce the transparent electrode layer in a short-circuit portion of the photovoltaic element, thereby selectively removing a short-circuit current path in the photovoltaic element due to a defect, wherein a voltage gradient when the forward voltage applied to the photovoltaic element is caused to drop to 0 V or a such forward voltage as to effect no reduction reaction of the transparent electrode layer is -15 V/s to -0.
1 V/s.
According to the present invention, it is preferred that the forward voltage is not less than the open circuit voltage of the photovoltaic element.
It is also preferred that the applied voltage is in a form of a trapezoidal or sawtooth wave that alternates between the forward voltage not less than the open circuit voltage of the photovoltaic element and 0 V or a forward voltage at which the reduction reaction of the transparent electrode layer does not occur