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

Abstract 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, RuO 2 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 H 2 SO 4 without applying any external bias. The device shows only 6 % loss of efficiency within 17 h of operation.