Impact of dispersion of carbon quantum dots of low concentrations into nematic liquid crystal mixture E7 on the optical properties and zeta potential of composite systems

Abstract

In recent years, carbon quantum dots (CQDs), a novel member of the carbon-based nanomaterial family, have exhibited exceptional physical and chemical properties. Dispersing quantum dots (QDs) into mesophase materials has emerged as an effective approach to modifying the physical properties of host liquid crystals. In this work, CQDs at concentrations of 0.25, 0.50, and 1.0 wt% were dispersed into the nematic liquid crystal mixture E7, and the effects of this dispersion on the optical properties and zeta potential of both pure and composite systems were investigated. The incorporation of CQDs significantly influenced the UV–visible absorbance and photoluminescence characteristics of the host medium. Fluorescence decay analysis revealed changes in the fluorescence lifetime upon CQD dispersion, indicating energy transfer from E7 to the CQDs. Zeta potential measurements showed increased values for 0.25 and 0.50 wt% CQD concentrations, while a decrease was observed at 1.0 wt%, compared to pure E7. These findings suggest that zeta potential analysis provides valuable insights into the stability and aggregation behavior of CQDs in the nematic host matrix.