Photoresponse of porphyrin thin-film electrode in the near-infrared

Photocurrent peaks in the near-infrared (NIR) are observed with ZnTPP thin-film electrodes in solutions. The peak positions compare well with those of the synergism spectrum for the Al/ZnTPP/Au dry cell although no NIR photocurrent is seen in the action spectrum of the dry cell. It is speculated that the magnitude of the NIR photoresponse attributable to a trace of ZnTPP photoproducts depends on the position of the LUMO levels of the impurity relative to the Fermi level of the ZnTPP solid at the metal/ZnTPP or solution/ZnTPP interface.