Hybrid organic–inorganic solar cells: Case of the all thin film PMeT(Y)/CdS(X) junctions

Hybrid organic–inorganic all thin film photovoltaic junctions PMeT(Y)/CdS(X) were investigated, where PMeT(Y) is the conducting polymer poly(3-methylthiophene) doped with various anions Y=CF3SO3−, ClO4−, BF4−, PF6−, and CdS(X) cadmium sulfide doped with various elements X=Cu, Ni, Al, As and Sb. CdS(X) films were spray deposited on conducting and transparent indium-tin oxide (ITO) glass, and PMeT(Y) films were electrodeposited onto the CdS(X) film to form the junction. The electrochemical investigation of the mechanism of electrodeposition and growth of the PMeT(Y) films by means of chronoamperometry, and of the charge transfer behavior of the PMeT(Y)/CdS(X) junctions by means of cyclic voltammetry revealed a strong effect of the nature of Y and X. The same strong effect of Y was also found with PMeT(Y)/ITO junctions, and may have some generality. It was showed that the best quality of contact between the organic and inorganic phases, from an electrochemical viewpoint and in solution, was obtained with the PMeTPF6−CdS(Sb) junction, pointing towards a similarly better photovoltaic performance in solid state. This was indeed the case, and it was found that higher short-circuit current, open-circuit photovoltage and energy conversion efficiency, approaching 4%, could be obtained with this junction.