Lead ethyl dithiocarbamates: efficient single-source precursors to PbS nanocubes

Lead ethyl dithiocarbamates have been successfully used as single-source precursors for the deposition of PbS using spin coating followed by annealing at moderate temperatures. The thin films were characterized using a powder X-ray diffractometer and were found to be face-centred cubic with the (200) plane being the most preferred orientation. Scanning electron microscopy images showed the formation of well-defined cubes. Optical band gaps of PbS thin films were estimated using Tauc plots as 0.72, 0.73 and 0.77 eV at annealing temperatures of 250, 300 and 400°C. These band gaps were all blue shifted from the bulk value of 0.41 eV. Energy-dispersive X-ray analysis was used to determine the composition of the thin films which showed an approximately 1 : 1 Pb to S ratio.