Vysotskite structured photoactive palladium sulphide thin films from dithiocarbamate derivatives

A series of palladium(ii) dithiocarbamate complexes [Pd(S ₂CNRR′)₂]·n(py) [where py = pyridine; RR′ = Bz, n = 1 (1); Cy, n = 1 (2); ⁿHex, n = 0 (3) and MeCy, n = 0 (4)] have been synthesized and characterized using various physicochemical techniques and their single crystal structures have been established. The decomposition modes and potential of the complexes as single source precursors (SSPs) for the development of palladium sulphide (PdS) thin films were investigated by thermogravimetric and derivative thermogravimetric (TGA/DTG) analyses. The PdS thin films were deposited on FTO conducting glass substrates at 400, 450 and 500 °C by the aerosol-assisted chemical vapour deposition (AACVD) technique and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) reveal that the deposit has a tetragonal structure with a 1 : 1 ratio of Pd : S. The shape and size of PdS crystallites and the texture of films depend on the deposition temperatures and the precursor type used. The direct band gap energy of 1.56 eV was estimated from UV-Vis spectroscopy of the PdS films fabricated from precursor (2) at 450 °C. The photoelectrochemical (PEC) properties of PdS films were studied by recording the current-voltage plots under alternating dark and illumination conditions. To the best of our knowledge, this is the first demonstration of PEC studies of photoactive PdS thin films fabricated using the AACVD technique using palladium(ii) dithiocarbamate complexes as precursors.