Method of patterning a thin-film photovoltaic layer stack

A method of patterning a thin-film photovoltaic layer stack comprising:

• providing a continuous layer stack, the layer stack comprising a substrate, a first electrode layer on the substrate, and a photovoltaic layer on the first electrode layer;
• immersing the layer stack into an electrically conductive solution;
• applying a bias voltage between the electrically conductive solution and the first electrode layer;
• selectively removing the photovoltaic layer along a first line and forming a first trench in the photovoltaic layer before or after immersing the layer stack into the electrically conductive solution;
• and
• converting a first material or a first material composition provided in at least a first portion of the layer stack into a first reaction product by an electrochemical reaction,
• wherein the first reaction product has an electrical conductivity that is lower than an electrical conductivity of the first material or the first material composition;
• wherein the layer stack is immersed into a salt solution containing at least one of:
• Zn, Cd, or Ca;
• and
• wherein at least one of the first material, the first material composition, or the first reaction product is transformed into one of:
• ZnMoO4, CaMoO4, or CdMoO4.

A method of patterning a thin-film photovoltaic layer stack comprising:

• providing a continuous layer stack, the layer stack comprising a substrate, a first electrode layer on the substrate, and a photovoltaic layer on the first electrode layer;
• immersing the layer stack into an electrically conductive solution;
• applying a bias voltage between the electrically conductive solution and the first electrode layer;
• selectively removing the photovoltaic layer along a first line and forming a first trench in the photovoltaic layer before or after immersing the layer stack into the electrically conductive solution;
• and
• converting a first material or a first material composition provided in at least a first portion of the layer stack into a first reaction product by an electrochemical reaction,
• wherein the first reaction product has an electrical conductivity that is lower than an electrical conductivity of the first material or the first material composition;
• wherein the first material or the first material composition of the first portion of the layer stack comprises a CIGS semiconductor material with a composition of Cux(In,Ga)ySez, with x+3y>2z;
• and
• wherein the first reaction product comprises a CIGS semiconductor material with a composition of Cux(In,Ga)ySez,Ow, with x+3y≤2(w+z) and w>0.