Polymer-electrolyte-based photoelectrochemical solar energy conversion with poly(3-methylthiophene) photoactive electrode

A photoelectrochemical cell based on neutral poly(3-methylthiophene) electrochemically coated on indium—tin oxide as a photoactive electrode, an amorphous poly(ethylene oxide) complexed with an I3−/I− redox couple as a solid polymer electrolyte, and thin transparent platinum film vapour deposited on indium—tin oxide as a counter electrode has been constructed. At catholic potentials a cathodic photocurrent was obtained indicating that the neutral poly(3-methylthiophene) is a p-type semiconductor. The short-circuit current and open-circuit voltage obtained with white light illumination at 100 mW cm−2 are 0.35 μA cm−2 and 140 mV, respectively. The monochromatic photon to current conversion efficiency obtained under illumination through back and front side is 0.3 and 0.6%, respectively. Studies of the photocurrent action spectra revealed that the poly(3-methylthiophene)/solid polymer electrolyte junction is responsible for the photocurrent generation. The intensity and time dependence of the short-circuit current and open-circuit voltage have been studied.