Stable hybrid organic/inorganic photocathodes for hydrogen evolution with amorphous WO ₃ hole selective contacts

Photoelectrochemical H ₂ production through hybrid organic/inorganic interfaces exploits the capability of polymeric absorbers to drive photo-induced electron transfer to an electrocatalyst in a water environment. Photoelectrode architectures based on solution-processed organic semiconductors are now emerging as low-cost alternatives to crystalline inorganic semiconductors based on Si, oxides and III–V alloys. In this work, we demonstrate that the stability of a hybrid organic/inorganic photocathode, employing a P3HT:PCBM blend as photoactive material, can be considerably improved by introducing an electrochemically stable WO ₃ hole selective layer, paired with a TiO ₂ electron selective layer. This hybrid photoelectrode exhibits a photocurrent of 2.48 mA cm ⁻² at 0 V RHE , +0.56 V RHE onset potential and a state-of the art operational activity of more than 10 hours. This work gives the perspective that photoelectrodes based on organic semiconductors, coupled with proper inorganic selective contacts, represent a sound new option for the efficient and durable photoelectrochemical conversion of solar energy into fuels.