Cd1-xHgxS thin film electrodes:: an electrochemical solar cell approach

The photoelectrochemical properties of a HgxCd1-xS alloyed/mixed type semiconductor/electrolyte interface are reported in this paper. HgxCd1-xS electrodes of varying composition (x = 0.0 to 0.5) were obtained on stainless steel substrates from salt solutions of cadmium and mercury in a volume stoichiometric proportion by employing a simple chemical growth process. Electrochemical solar cells were devised from these electrodes and the interface properties have been studied as a function of the photoelectrode composition x. The dynamic V-I characteristics in the dark showed the rectifying nature of the junctions with the presence of recombination centres at the interface. The V-C characteristics showed that introduction of Hg into CdS makes CdS more negative (maximum at x = 0.05), thereby increasing the flat band potential and consequently the open circuit photopotential. The short circuit photocurrent is also found to be increased. The efficiency eta (%) and form factor FF (%) have been found to be enhanced from 0.012% to 0.054% and from 35.5% to 46.8%, respectively (at x = 0.05). The computation of other cell parameters (n(d), n(L), phi(B), R-S R-sh) also revealed that the cell performance is improved after addition of small traces of Hg into the host CdS.