Method of patterning a thin-film photovoltaic layer stack

A thin-film photovoltaic layer stack comprising:

• a planar shaped substrate;
• a bottom electrode layer residing over the planar shaped substrate, the bottom electrode layer including:
• an electrically conductive metal;
• a first portion of the bottom electrode layer, the first portion including:
• a lower electrical conductivity than the electrical conductivity of the bottom electrode layer;
• the first portion converted into a first reaction product by an electrochemical reaction;
• a gap defined by the first reaction product;
• a first solar cell including a first top and a first bottom;
• a second solar cell including a second top and a second bottom;
• the first solar cell and the second solar cell residing in the gap defined by the first reaction product;
• the first bottom is electrically connected to the second top;
• the second bottom is electrically insulated from the first bottom;
• a photovoltaic layer residing over the bottom electrode layer;
• a window layer residing over the photovoltaic layer;
• a top electrode layer residing over the window layer;
• a first trench formed in the photovoltaic layer and in contact with the bottom electrode, the first trench including:
• a first edge defined by the formed first trench;
• a second edge opposing the first edge and defined by the formed first trench;
• a second trench formed in the photovoltaic layer and across the second edge and the second trench is adjacent and parallel to the first trench;
• and
• a third trench formed by partial removal of the photovoltaic layer, the window layer, and the top electrode layer.