Functional codoped ZnSe:Cu, Mn quantum dots(QDs): Microstructure, calorimetric and photoluminescence properties

Abstract

In the present work, undoped ZnSe, and Zn1-x-y Cux Mny Se (x = 0.001, y = 0, 0.001, 0.010 0.015, 0.02 and 0.04 mol) codoped-quantum dots (cdQDs) of mean crystallite size within the range of 1.12 to 1.63 nm are synthesized employing the simple microwave irradiation (MWIR) assisted method; Different synthesis regimes of variable MWIR times and also Mn content are performed for ZnSe:Cu-Mn QDs. Structural, optical properties and melting point of the as-synthesized ZnSe QDs are studied by XRD, FESEM equipped with EDX and Map, TEM, Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) analysis. XRD confirms the incorporation of Mn and Cu in ZnSe structure with the tunable size by changing the synthesize conditions; TEM results indicate spherical particles, most of which had a diameter of about 5 nm. Results of photoluminescence (PL) investigations show the synthesis condition dependence nature of the samples, suggesting their application in green-region sensors/biosensors; Mn doping causes more extent of PL in to the light wavelengths; doping with transition metals (TMs) impurities and employing MWIR cause an enhancement in the intensity and peak shift of PL band toward higher wavelengths, which influence on the optical properties of semiconductors. The FTIR absorption peaks for the understudied samples show the formation of ZnSe structure (the interaction between Se2− and Zn2+ ions) and insertion of Mn and Cu ions into their lattices; The Experimental and empirical melting temperature of synthesized nanomaterial are investigated; DSC analysis shows that nanoparticles melting point of the present nanoparticles are 600 °C lower than that of the bulk ZnSe owing melting point of 1520–1525 °C. Empirical size dependency of melting point shows that at lower than the Bohr radius of ZnSe (~8 nm), reasonable fast decrease in melting point occurs.