Effect of manganese doping on the photoluminescence characteristics of chemically synthesized zinc sulfide nanoparticles

Abstract

The studies on luminescent II-VI semiconducting nanomaterials have attracted widespread attention recently, due to their potential applications in optoelectronic and biophotonic devices. Amongst other II-VI semiconductor nanoparticles (NPs), Mn 2? -doped ZnS NPs having large exciton binding energy and wide direct band gap at room temperature have drawn considerable attention for exploring its interesting optical properties. However, in this report, water-soluble Mn 2? -doped ZnS (ZnS:Mn) NPs with Mn 2? concentration varying between 1.5 and 5% (wt%) have been synthesized by chemical co-precipitation method at room temperature. X-ray diffraction (XRD) studies and the analysis of the selected area electron diffraction (SAED) pattern, obtained from transmission electron microscopy (TEM), confirmed the formation of zinc blende structure in all the synthesized samples. The particle sizes of the samples, as obtained from the optical absorption studies, varies between 2.2 and 2.7 nm with the increase of Mn 2? concentration between 1.5 and 5%. The room temperature photoluminescence (PL) emission measurements revealed the presence of yellow-orange emission band in all the Mn 2? -doped samples which is attributed to Mn incorporation in ZnS. The Gaussian fittings of the measured PL spectra of all the samples show the presence of four PL peaks. Amongst the four PL peaks three peaks appeared at 445, 476, and 520 nm in all the samples but the fourth yellow-orange emission peak suffered a red shift from 593 to 600 nm with increasing Mn 2? concentration from 1.5 to 5%. In this report no quenching of yelloworange emission peak is observed up to 5% Mn 2? doping concentration in ZnS. The synthesized water-soluble ZnS:Mn NPs can be further functionalized for using them as biolabels.

Optical properties of tin oxide nanoparticles prepared by laser ablation in water: Influence of laser ablation time duration and laser fluence

“…If the size of the prepared nanoparticles is greater than the value of Bohr exciton radius of bulk SnO 2 , 2.7 nm [16], samples have a weak confinement and shift of absorption band gap due to quantum size effect is very small. Under such confinement the average particle size of the prepared nanoparticles is calculated from the blue shift of band gap energy through a simple relation derived in the effective mass model [23][24][25],…”

Mn2+ ion influenced optical and photocatalytic behaviour of Mn–ZnS quantum dots prepared by a microwave assisted technique

“…Kole and co-workers have reported that the increase in particle size and decrease in density of surface states leads to a red shi in emission wavelength. 30 In addition to this, Karar et al 28 have mentioned that the red shi with Mn ion concentration can be attributed to a change in band gap structure of ZnS upon Mn 2+ ion incorporation or Mn-Mn ion interactions. All these points suggest that the Mn ions are getting well incorporated into the host ZnS lattice and shiing the emission to a longer wavelength with increasing doping concentration.…”

Preparation of metal sulfide mixtures in montmorillonite by solid–solid reactions

“…The intensity of the two bands (at 451 and 469 nm for MnS/ZnS@Mt) was also increased together with the increase of the band due to MnS and ZnS, indicating the increase of the photoluminescence intensity of the product. The yellow emission shoulder at around 550 nm was clearly seen in the PL spectra of MnS/ZnS@Mt and MnS/CdS@ Mt, supporting the incorporation of Mn 2 + ions in the lattice site of ZnS or CdS (Hu and Zhang, 2006;Kole and Kumbhakar, 2011). The photoluminescence intensities of the products increased in the followed sequence of ZnS/CdS@Mt b MnS/CdS@Mt b MnS/ZnS@Mt, indicating the quantum confinement effect.…”