Thin-film solar cells produced by physical vapour deposition

The theoretical and experimental studies of thin-film solar cells carried out at Newcastle Polytechnic are described. A theoretical model has been developed in which optical interference effects lead to improved photocurrents at small thicknesses of the Cu2S or CuInSe2 absorbing layers, and the optical properties of the substrate can have a significant effect on the photocurrent. The results for CdS/Cu2S and CdS/CuInSe2 junctions are presented, and it is found that the optimum thickness of the absorbing layer is 0.1-0.15¿¿m in both cases. The dry-barrier technique for producing CdS/Cu2S junctions has been investigated in some detail, and the techniques that have been developed are described. Most of our work with the dry-barrier technique has used thermally evaporated cadmium sulphide, and the efficiency of these cells is estimated to be up to 6%. The more recent work on junction formation on sputtered cadmium sulphide is also described breifly.