Influence of interface defects on the optical properties of InP/ZnS quantum dots by low temperature synthesis of InP core

We present a series of investigations focused on the effect of synthesis temperature on the optical characteristics of InP/ZnS QDs. Absorption spectra confirmed the successful synthesis of InP QDs under a temperature as low as 140 degrees C. Because of the poor optical characteristics possibly caused by the inherently high defect states on the surface of InP QDs, a modified ZnS shell overcoating was applied on the InP QDs. An InP core synthesized at a relatively low temperature of 160 degrees C or less is presumed to possess fewer surface defects; this was confirmed as a reduction in the red-shift due to the shell coating. A satisfactory quantum yield of 52% was obtained from the InP/ZnS QDs synthesized at a reaction temperature and reaction time of 140 degrees C and 20 h, respectively, with the ZnS shell coating. Thus, we successfully synthesized InP/ZnS QDs using an InP core synthesized at a low temperature of 140 degrees C through our suggested shell coating process.