Bogdanoff, P.; Stellmach, D.; Gabriel, O.; Stannowski, B.; Schlatmann, R.; van de Krol, R.; Fiechter, S.: Artificial Leaf for Solar Water Splitting based on a Triple–Junction Thin Film Solar Cell and a PEDOT:PSS / Catalyst Blend . Energy Technology 4 (2016), p. 230–241
10.1002/ente.201500317

Abstract:
The present work reports on an integrated water splitting device based on a triple junction silicon-based solar cell (a-Si:H/ a-Si:H/ µc-Si:H) in superstrate configuration modified with catalysts at the back and front contacts. In this configuration the solar cell is illuminated via 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 type. 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 using a conductive polymer (PEDOT:PSS). A solar-to-hydrogen efficiency of 3.4 % is obtained under AM1.5G and 1000 W/m² in 0.5M H2SO4 without applying any external bias. The device shows only 6% loss of efficiency within 17 hours of operation.