Nano-hybrid luminescent dot: synthesis, characterization and optical properties

A series of nano-hybrid light emitting dots with diameter range from 2 nm to 4 nm were synthesized through grafting organic conjugated chains directly onto an inorganic rigid cage polyhedral oligomeric silsesquioxanes (POSS). The effect of chain length, side groups, polarity of solvents on the property of light emitting dots were studied using FTIR, XRD, DSC, UV, PL, AFM and SEM. The unique structure of these nano-hybrid dots renders them with excellent PL properties which are much different from bulk organic molecules or conjugated polymers. The incorporation of conjugated molecules onto POSS transforms the oligo-conjugated arms from crystalline state to non-crystalline solid which can be solution processed. The PLQE (PL quantum efficiency) of the oligo-conjugated arms in condensed state increases significantly after grafting onto POSS. The light emitting dots are very sensitive to the polarity of organic solvents due to their nano-scaled size. PL spectrum of the nano-hybrid dots in solid film was blue shift from that in most of organic solvents.