A combinatorial approach to the optimisation of Cd(1−x)ZnxS layers for CdTe solar cells

A combinatorial methodology has been adopted to determine the optimum composition of a Cd(1-x)Zn_xS window layer for CdTe solar cells. The methodology generated a large, self consistent dataset which permitted an unambiguous relationship between x, conversion efficiency and related cell parameters to be determined. An optimum composition of x = 0.57 was shown to maximise cell efficiency. Analysis of J - V curves, measured over 72 separate cells show that both short circuit current, J_SC, and fill factor, FF, values increase with respect to x over the range 0.1-0.57. EQE measurements show that further increases in J_SC value are limited by the band gap of the highly resistive transparent (HRT) ZnO layer. The methodology demonstrates a rapid route, compared to conventional experiments, to the further optimisation of CdTe solar cells.