We report the effect on the phase transitional behavior of 8OCB liquid crystal (LC) doped with functionalized CdSe/ZnS quantum dots (QDs) in different concentrations. The temperature-dependent data of high-resolution optical birefringence and dielectric anisotropy are utilized to characterize the critical anomaly for both the isotropic-to-nematic ($I-N$) and nematic-to-smectic-$A$ ($N\text{−}\mathrm{Sm}A$) phase transitions. The obtained results reveal that the order parameter exponent $\left(\beta \right)$ for the pure LC is found to be $\beta =0.249$ and does not vary upon the inclusion of QDs in the pure matrix. It describes the weakly first-order characteristic of the $I-N$ phase transition for all the studied samples, which falls within the limit of the tricritical hypothesis. Conversely, depending on the range of the $N$ phase, we observed a nonuniversal nature of the specific heat capacity critical exponent $({\alpha }^{\prime }$) linked with the $N\text{−}\mathrm{Sm}A$ phase transition for all the studied samples. A relative comparison was made amongst the ${\alpha }^{\prime }$ values extracted from both the anisotropy data, and further, a theoretical relationship is established with these exponent values. The coupling strength among the $N$ and $\mathrm{Sm}A$ order parameters is determined using the optical birefringence data and discussed from the perspective of mutual interaction between the LC-QDs ligands. The results signify that a strong ligand-ligand interaction between neighboring QDs effectively reduces the $N$ range and slightly influences the $N\text{−}\mathrm{Sm}A$ phase transition.

• Received 23 March 2023
• Accepted 10 July 2023

DOI:https://doi.org/10.1103/PhysRevE.108.034701