Synthesis and characterization of silver diethyldithiocarbamate cluster for the deposition of acanthite (Ag2S) thin films for photoelectrochemical applications

Acanthite (Ag2S) thin films were fabricated on fluorine doped tin oxide coated conducting glass substrates by aerosol assisted chemical vapor deposition (AACVD) using silver cluster [Ag4{S2CN(C2H5)2}3(C5H5N)2]n·nNO3·2nH2O (1) [where (S2CN(C2H5)2) = diethyldithiocarbamate, C5H5N = pyridine] as a single source precursor. Cluster (1) was synthesized by the reaction of sodium diethyldithiocarbamate with silver nitrate in a mixture of acetone and pyridine. (1) was analyzed by melting point, elemental analysis, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, thermogravimetry and single crystal X-ray studies. Single crystal X-ray studies showed that (1) crystallizes in the triclinic crystal system with a = 11.4372(3), b = 11.6768(3), and c = 16.3672(4) Å and α = 105.817(3), β = 97.891(3), and γ = 93.274(3)° in the space group P-1. Thermogravimetric analysis revealed that (1) undergoes facile thermal decomposition at 400 °C to give a stable residual mass consistent with the formation of Ag2S. Thin films grown from a 0.02 M solution of (1) in pyridine at 350 and 400 °C using AACVD technique were characterized by powder X-ray diffraction, field emission scanning electron microscopy (FESEM), energy dispersive X-ray and ultraviolet-visible spectrophotometry. FESEM images of the films exhibited well-defined nanorods with length > 1000 nm and diameter 100-150 nm grown without any cracks, fractures or directional preference. A band gap of 1.05 eV was estimated by extrapolating the linear part of a Tauc plot recorded for the films. The photoelectrochemical (PEC) characteristics recorded under Air Mass 1.5 illumination indicated a photocurrent density of 220 μA cm− 2 at 0.0 V vs Ag/AgCl/3 M KCl. The optical and PEC characteristics of the deposited thin films proved their suitability for PEC applications.