Green Synthesis And Application Of CdSe Quantum Dots

Quantum dots (QDs), or colloidal semiconductor nanocrystals, werestudied widely as a kind of high performance inorganic fluorescent materialswith high fluorescence efficiency and quantum size effect.CdSe QDssynthesized by Traditional high-temperature organic phase have advantagesof narrow size distribution, controllable size and good luminous performance.However, the use of expensive and toxic chemical agents, such asTrioctylphosphine (TOP), Trioctylphosphine oxide (TOPO), dimethylcadmium (Cd(CH3)2), hexyldecylamine (HDA) and octadecene (ODE), wouldpollute the environment and cause great harm to researchers, is not conduciveto realize industrialization. To develop a low-cost, green, fast, safe andmass-production route for synthesis of high quality CdSe QDs is a major goalof the development of green synthetic nanocrystal chemistry. In this paper, agreen organic synthesis of CdSe QDs was presented mainly from thefollowing three aspects:(1) CdSe QDs were prepared by the castor oleic acid-castor oil system.Three factors of reaction time, reaction temperature, and reaction materialratio of the preparation process to the particle size, size distribution, andfluorescence emission performance of CdSe QDs were studied systemically.Their morphologies, sizes, structures of crystals, ultraviolet and fluorescenceproperties were characterized by electron transmission microscope (TEM),X-ray diffraction (XRD), fluorescence spectroscopy (PL), Fourier transforminfrared spectrometer (FT-IR) and ultraviolet visible absorption spectroscopy(UV-vis) respectively. The results show that different sizes of CdSe QDs can be synthesized successfully under reaction temperature at220～250oC, Cd/Sematerial ratio of1:10to2:1, and the reaction time from10s to the600s.(2) After optimization, CdSe QDs with the size of2.53nm and3.28nmwere obtained respectively when the ratio of Cd:Se is1:5, the reactiontemperatures are240oC and220oC, and the reaction times are60s and300srespectively; and CdSe QDs with the size of3.69nm and5.54nm wereobtained respectively when the ratio of Cd:Se is2:1, the reaction temperatureis240oC, and the reaction times are300s and600s respectively.(3) CdSe-polyurethane nanocomposites with high fluorescence and heatresistant were prepared successfully by a one-step green synthetic route usingdifferent sizes of CdSe QDs obtained by the above preparation ascross-linking agents.