The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH(3))(2))(3). The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Alcoholic media dispersible YAG : Ce colloidal nanocrystals were prepared by a solvothermal route. To obtain highly efficient nanocrystals, the Ce concentration and the reaction time were optimized. The surface of the nanocrystals was further modified with oleylamine to make them dispersible in a non-polar solvent. The luminescent characteristics such as luminescent efficiency, band width and peak wavelength of Ce3+ d → f transition of the YAG : Ce nanocrystals were compared with those of a micrometre-sized phosphor. The host of nanocrystals was compositionally modified by partially or completely substituting Y3+ with Tb3+ or Gd3+ ions, through which the Ce3+ emission peaks were red-shifted due to an increased crystal field strength around Ce3+ luminescent centres. White light-emitting diodes (LEDs) were fabricated by coating these YAG : Ce nanocrystals on blue LED chips and their electroluminescent properties were compared with those of a bulk YAG : Ce-based white LED.

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Undoped, Tb(3+)- and Eu(3+)-doped ZnGa(2)O(4) colloidal nanocrystals were synthesized by a nonhydrolytic hot solution chemistry. Undoped nanocrystals exhibited an intrinsic blue emission peaking at 437 nm by self-activated transition. The emissions of Tb(3+)-and Eu(3+)-doped ZnGa(2)O(4) nanocrystals consisted of their own characteristic green and red line peaks ((5)D(4)-(7)F(j) transitions), respectively. Synthetic parameters such as activator concentration and reaction time were varied to investigate their effects on luminescent properties. Tb(3+)-doped colloidal nanocrystals synthesized for a short reaction time showed an unprecedented, exclusively green luminescence with the host blue emission effectively suppressed. On the other hand, the emission of Eu(3+)-doped ones was weak with the host emission persistently present regardless of reaction time.