Molecular conformation dependent emission behaviour (blue, red and white light emissions) of all-trans-β-carotene-ZnS quantum dot hybrid nanostructures

A novel hybrid material consisting of all-trans-beta-carotene and ZnS quantum dots (QDs) was prepared by two different controlled experiments and their photophysical properties were investigated in detail. Depending upon the preparation method, the beta-carotene molecule had formed either an upright or wrapped conformation around the ZnS QDs and consequently the interaction between these two hybridizing systems was either charge transfer induced or electrostatic in type, respectively. Optical absorption, Raman and FTIR investigations have confirmed the two different conformations of the molecule around the ZnS QDs. Because of the two different conformations and the consequent interactions, different emission colours, such as blue and red wavelengths were obtained from these hybrids. We were also able to obtain white light emission by using cadmium doped ZnS QDs for the hybrid preparation.