Analysis of spray pyrolysed copper zinc sulfide thin films using photoluminescence

Copper zinc sulfide (CuZnS) is an upcoming photovoltaic material. The room temperature photoluminescence (PL) study of thin films of this material synthesized using automated chemical spray pyrolysis (CSP) is reported. The PL spectra from CuZnS comprises of a broad emission constituted by multiple peaks. In this work, ratio of intensities of peaks around 660 nm and 550 nm (I660/I550) as a function of copper ion concentration and deposition temperature is studied. The nature of spectra at lower and higher deposition temperatures seem to be significantly different. Existence of mutually interacting but independent Cu and Zn related phases are evident from PL spectra. Lower deposition temperatures favor copper related phases and higher deposition temperatures promote zinc related emissions. PL technique is used as a non-destructive tool in bringing out the potential of the material to be used as an absorber and p-type window layer in solar cell.