Photovoltaic action in a self-assembled monolayer of hemicyanine dyes on gold from dissociation of surface plasmons

Hemicyanine dye molecules, containing a thiol functionality, form a self-assembled monolayer (SAM) on thin films of gold. The combined SAM-gold layer system supports surface plasmons and can be converted into a diode using a liquid electrolyte top contact. Diodes fabricated on a quartz prism allow for incoupling of incident light to surface plasmons and show a spontaneous photocurrent under short-circuit conditions. Measurement of the short-circuit photocurrent as function of incident angle of the light shows that the photocurrent arises from dissociation of surface plasmons into pairs of charge carriers.