A Novel Thermochemical Method for Fabrication and Theoretical Explanation of High Luminescent Mn-Doped CdS Nanoparticles

Abstract

In this paper, fabrication and characterization of bare and doped CdS nanoparticles as well as investigating the luminescence properties of these particles as an important II-VI semiconductor are presented. A novel Thermochemical method was used for synthesis of these quantum dots. Thiols were used as the capping agent to prevent further growth during fabrication process. The application of TGA as a capping agent instead of TG was studied as a novel idea in this paper and was used practically in the synthesis of semiconductor nanoparticles. Using this process resulted in particles with sizes between 3 -7 nm. Several samples were synthesized and characterized under various Mn ions doping ratio from 1:10 to 1:180, different temperatures from 40˚C to 96˚C and different pH values from 6 to 10. Synthesis of CdS nanoparticles with high Mn ions concentration resulted in luminescence decrement, while luminescence of nanoparticles was increased by decreasing Mn/Cd doping ratio until Mn:Cd = 1:180. The best fabrication temperature was obtained at 96˚C and the highest luminescence was observed at the pH value of 9. A theoretical explanation for the behavior of fabricated high luminescent quantum dots is presented based on the principles of quantum mechanics. Among semiconductor nano-materials, CdS nanoparticles have attracted considerable attention due to their unique properties, which do not present in their bulk materials [2]. These unique properties introduce them as the important and useful materials for various applications such as solar cells, photodetectors, light-emitting diodes, photoelectrolysis and biological labels [3] [4] [5] [6].Nanoparticles have been grown in a variety of ways, namely precipitation in the solid phase [7] [8], using porous materials as templates [9], growth in nano-sized micelles and precipitation in the liquid phase [10] [11].