Synthesis and characterization of cadmium-free ZnSe quantum rods and their photonic properties

Abstract

Semiconductor quantum dots have attracted much attention in next generation displays, due to the fact that their tunable band gaps and narrow emission bandwidths allow wide gamuts in color space. Thus far, green and red quantum dots have already achieved theoretical external quantum efficiencies of 20% in light-emitting devices. However, blue quantum dots still lagged behind in efficiency. Recently, it has been reported that external quantum efficiency can be enhanced by morphology control of quantum structure. In particular, quantum rods are considered as one of the potential structures for improving efficiency. In this thesis, Chapter 1, recent researches of next generation display using semiconductor quantum dots and quantum rods are introduced. In Chapter 2, Cd-free ZnSe@ZnS quantum rods have been synthesized with a tunable aspect ratio by varying the relative amount of metal precursors and solvents. The photonic properties of quantum rod are characterized in detail. In Chapter 3, we expected that the insertion of tellurium into the ZnSe@ZnS quantum rods would largely vary the fluorescence wavelength to the lower energy region. Therefore, Cd-free ZnTeSe@ZnS quantum rods were attempted to synthesize by the alloy with tellurium in the presence of amine ligands. The photo-enhanced emission was successfully tuned by adjusting the amount of tellurium in the quantum rods. In conclusion, this work provided not only a facile synthesis method of ZnSe@ZnS quantum rods but also the roles of quantum rod structure with a variable aspect ratio when adapted in LED. In addition, the emission range of ZnTeSe@ZnS was successfully tuned from violet to green by changing the alloy of tellurium.