Artificial Leaf for Water Splitting Based on a Triple-Junction Thin-Film Silicon Solar Cell and a PEDOT:PSS/Catalyst Blend

An integrated water‐splitting device based on a triple‐junction silicon‐based solar cell (a‐Si:H/a‐Si:H/μc‐Si:H; a‐Si=amorphous silicon, μc‐Si=microcrystalline) in superstrate configuration modified with catalysts at the back and front contacts is described. In this configuration, the solar cell is illuminated by the glass substrate, while the back and front contacts are arrayed laterally at the opposite side of the cell. Therefore, neither shadowing nor light scattering by evolved gas bubbles can detrimentally affect the solar‐to‐hydrogen efficiency of this artificial leaf. By modifying the contact layers of the cell, its chemical stability in acid electrolyte is significantly improved. To test the system, RuO2 and Pt black catalysts are fixed on the contacts as a blend by using a conductive polymer [poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)]. A solar‐to‐hydrogen efficiency of 3.4 % is obtained under AM1.5G illumination and 1000 W m−2 in 0.5 M H2SO4 without applying any external bias. The device shows only 6 % loss of efficiency within 17 h of operation. Artificial leaf: One of the most attractive solutions to store solar energy is the electrolysis of water by integrated devices composed of highly developed solar cells and catalysts for the water‐splitting process. Challenging issues include the stability and solar‐to‐hydrogen efficiency of the device in aqueous electrolyte. A triple‐junction amorphous silicon‐based solar cell modified with noble‐metal catalysts is presented to split water with energy from solar light.