Potassium-ion doped Cu(In,Ga)Se2 thin films solar cells: Phase formation, microstructures, and photovoltaic characteristics

Current-voltage characteristics of solar cells based on the prepared Cu(In,Ga)Se2 films without potassium and added with and 1.0 mol% potassium ions without KCN etching treatment. Inset: Photovoltaic properties of solar cells based on the prepared Cu(In,Ga)Se2 films with various potassium-ion content without KCN etching treatment.