Synthesis And Characterization Of Znse, Znse:Mn And ZnSe:Mn/nZnS Nanocrystals

Because of the unique optical properties which were induced by the quantumconfinement effect, semiconductor nanocrystals (NCs) indicate a large variety ofapplication prospects in light-emitting devices, solar cell, semiconductor laser,electroluminescent devices and biological detection. In recent years, as a perfectsemiconductor material with broad bulk band gap (2.80eV), ZnSe NCs have been widelystudied. So, in this paper, the synthesis and characterization of ZnSe NCs with perfectdispersity and high photoluminescence (PL) quantum yield (QY) in organic solvents andresearch the influence of the pulsed high magnetic field on the optical property werecarried out.Firstly, by using selenium powder dissolved in the mixture of oleyamine anddodacanethiol as Se precursor and znic stearate dissolved in1-octadecene as Zn precursor,we synthesized ZnSe NCs with hot injection strategy. The NCs performed perfect opticalproperty when the injection temperature of Se precursor was250°C and the growth timeof ZnSe was20min. The X-ray power diffraction (XRD) pattern showed the NCs werecubic zinc blende phase. The NCs were approximately spherical and well dispersedwithout agglomerate, the mean diameter was4.55nm.Secondly, we synthesized the ZnSe:Mn NCs with nucleation strategy and found that theNCs exhibited perfect optical property when the concentration of Mn was2%, injectiontemperature of Se was250°C, growth time of the core was5min. From the emissionspectrum, we found PL peak of the NCs was585nm. The XRD patterns and TEM imagesshowed the NCs were cubic zinc blende phase and well dispersed with the approximatelyspherical shape, the mean diameter was6.27nm.Thirdly, we obtained the ZnSe:Mn/nZnS NCs based on the synthesis of the ZnSe:MnNC by using the epitaxial growth strategy. From the XRD pattern, we got that theZnSe:Mn/nZnS was still cubic zinc blende phase. With the increasing of the layer of ZnS,the peak of the X-ray diffraction pattern shifted to the large angle of ZnS crystal form(XRD), the mean diameter increased from6.27nm to9.22nm (TEM), red shift happenedfor the PL spectrum and the red shift amplitude for the whole process reached about20nm.When the shell of the ZnS increased to3, the PL intensity was the highest (56.6%). Finally, We detected the PL spectrum of ZnSe:Mn (2%) under the temperature of83Kand pulsed high magnetic field, the PL intensity was100percent enhanced comparingwith the room temperature. However, the PL intensity increased slowly with thesenhancing of the magnetic field.