Toward Stable Solar Hydrogen Generation Using Organic Photoelectrochemical Cells

MARTA HARO; CLAUDIA SOLIS; GONZALO MOLINA; LUIS OTERO; JUAN BISQUERT; SIXTO GIMENEZ; ANTONIO GUERRERO

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 119 p. 6488 - 6494

1932-7447

Organic photoactive materials are promising candidates for the generation of solar fuels in terms of efficiency and cost. However, their low stability in aqueous media constitutes a serious problem for technological deployment. Here we present organic photocathodes for the generation of hydrogen in aqueous media with outstanding stability. The device design relies on the use of water-resistant selective contacts, which protect a P3HT:PCBM photoactive layer. An insoluble cross-linked PEDOT:PSS hole-selective layer avoids delamination of the film, and an electron-selective TiOx layer in contact with the aqueous solution electrically communicates the organic layer with the hydrogen-evolving catalyst (Pt). We developed a novel method for the synthesis of the TiOx layer compatible with low-temperature conditions. Tuning the thickness of the TiOx/Pt layer leads to a trade-off between the achievable photocurrent (~ 1mA/cm2) and the stability of the photocathode (stable hydrogen generation of 1.5 μmol/ h1 cm2 for >3 h).