The photocurrent at the interface between a molecular crystal and an electrolyte in presence of quenching of excitons by a species in solution

Abstract

AbstractThe rate constant for the quenching of excited molecular states at the interface between a molecular crystal and an aqueous electrolyte was determined from photoinjection experiments. The situation was analysed in which radiation passes through an electrolyte that forms one of the electric contacts to the crystal. It is assumed that excitons generated by absorption of photons within the solid diffuse to the crystal/solution interface and there react with charge and energy acceptor species in solution. The quantum efficiency of the charge separation reaction was determined from the limiting photocurrent and compared with the value which would be expected in the absence of quenching. The quenching rate constant thus determined was compared with a value derived from the application of Förster's treatment of resonance energy transfer upon quenching at the interface between a solid and an electrolyte. It was shown that at the interface between an anthracene electrode and a solution of Na2IrCl6 virtually all the energy of the excitons is transferred to the IrCl62− by resonance energy transfer.