Cobalt (Co) doped zinc phosphide nanoparticles: solid state reaction synthesis, structural, morphological, optical and photoluminescence properties

Cobalt (Co)-doped zinc phosphide (Zn (3-x) Co x P 2 ) nanoparticles were synthesized using a solid-state reaction technique with compositions of x = 0.00, 0.02, 0.06, and 0.08. Their structural, optical, morphological, elemental, and photoluminescence properties were systematically investigated. Based on the X-ray diffraction (XRD) patterns, it was determined that every sample has a tetragonal structure, and the patterns also revealed the absence of other phases. The lattice parameters decreased (a = b = 8.132 Å to 8.102 Å and c = 11.124 Å to 11.092 Å) with increasing dopant (Co) content. Scanning electron microscopy (SEM) study shows significant particle aggregation with increasing Co concentration, reaching ~ 200 nm. Energy-dispersive X-ray spectroscopy (EDS) reveals the existence of Zn, P, and Co in the Zn 3 P 2 lattice, showing that Co was successfully incorporated. The Kubelka–Munk function was used in diffuse reflectance spectroscopy to investigate the optical properties. The bandgap value was found to rise with doping from 1.413 to 1.436 eV. Photoluminescence studies revealed the presence of ultraviolet, violet, and blue emission peaks under excitation at 192 and 248 nm.