Fabrication and characterization of miniaturized photo-electro-chemical solar cells

This work presents implementation and characterization of a micro-fabricated electrolyte-based photo-electro-chemical (PEC) solar cell. The cell consists of a thin p-type silicon membrane acting as the photo-cathode that houses a micro-cavity filled with zinc chloride electrolyte. The cavity is sealed by a sheet of zinc acting as the anode. The cell utilizes a semiconductor-electrolyte junction as opposed to the solid-state P-N junction used in conventional photovoltaic cells. The thin silicon membrane is formed by controlled etching of the micro-cavity and allows photons or their resulting electron-hole pairs to penetrate and reach the silicon-electrolyte junction inside the cavity to generate a photo-current. For an assembled PEC cell with silicon electrode area of 3.87mm², a maximum power of 0.044mW was achieved under 1 sun illumination translating into 1.1% efficiency.