All-solid-state photoelectrochemical energy conversion with the conjugated polymer poly[3-(4-octylphenyl)-2,2′-bithiophene]

The behaviour of an all-solid-state photoelectrochemical cell containing a conjugated polymer, poly[3-(4-octylphenyl)-2,2′-bithiophene], film as a photoactive electrode, a solid polymer electrolyte, poly[oxymethylene-oligo(oxyethylene)] complexed with redox couple, and a counter electrode was studied. The cell converted light to electricity, operating in a regenerative mode. The short circuit current and open circuit voltage generated with white light illumination at approximately one sun were 0.4 μA cm−2 and 240 mV, respectively. Evidence for the diffusion of the redox species inside the photoelectrode is reported. Two redox couples, I3−/I− and Eu2+/3+ have been used. Action spectra revealed that the active junction responsible for the photocurrent generation was that between the conjugated polymer and the polymer electrolyte. All tested models gave poor fits to these action spectral data. Steady state and transient photocurrent-time dependence studies indicated that the system was relatively stable towards light irradiation. The thickness dependence of the photocurrent, the time dependence and incident light intensity dependence of the short circuit current and the open circuit voltage were also studied.