Effect of Nanosecond Laser Beam Shaping on Cu(In,Ga)Se2 Thin Film Solar Cell Scribing

The Cu(In,Ga)Se2 (CIGS) thin film solar cell is a promising material architecture considering its high photovoltaic (PV) efficiency at low material cost. Recently, the authors demonstrated all laser based mini-module fabrication on a transparent conducting oxide (TCO) based CIGS architecture, using a cost-effective nanosecond laser beam illuminated from the transparent glass substrate side. While indium tin oxide (ITO) is a promising TCO to this end, allowing ohmic contact with CIGS and low sheet resistance, it suffers from unwanted damage upon laser scribing based on its preferred thickness of ∼200 nm. Therefore, in this study, we investigate the effect of laser beam size and shape on ITO damage during P2 laser scribing. Although use of an enlarged laser spot could mitigate the damage issue, larger scribing width increased the dead zone. Thus, we have implemented the elliptical laser beam shaping technology so that a longer beam axis can suppress the ITO damage also maintaining high scribing speed while ...