Simple synthesis of Ag-doped CdS nanostructure material with excellent properties

Cadmium sulfide (CdS) is the most significant material due to discrete energy levels, size dependent optical properties, turntable band gap, quantum size effect, large photo resistivity and a wide range of photo-electronics, optical, electrical and luminescence applications. In this work, the precursors AgNO3, Cd (CH3CO2), Na2S and NH4OH are used for synthesis of Ag-doped CdS nanostructure by simple chemical co-precipitation method. The variation in properties of CdS has been checked by varying doping concentration of silver from 2.5 to 10%. The Powder X-ray diffraction results confirmed that the pure CdS has hexagonal wurtzite phase structure while Ag-doped CdS diffraction peaks confirmed the hexagonal structure. Energy dispersive X-ray spectroscopy shows elemental composition and bond formation between different functional groups. The scanning electron microscopy results showed that nanoparticles are in the range of 50-100 nm and have spherical shape while Ag-doped CdS found in nanoclusters due to aggregation. The FTIR spectra confirmed Ag-2-S and Cd-S stretching bonds due to doping. A blue shift in the band gap of CdS nanoparticles (4.2 eV) as compared to bulk CdS (2.58 eV) has been reported in UV spectrum. By increasing the Ag concentrations, it is decreased to 2.95 eV due to quantum size. Absorption spectra for Ag-doped samples are red shifted as compared to pure CdS sample. These remarkable properties of high optical transparency, decreasing band gap and absorption coefficient in electromagnetic spectrum (visible region), makes it applicable in worthwhile and efficient thin film solar cells.