Interfacing of Surface Functionalized Carbon Quantum\nDots with Antiferroelectric Liquid Crystalline Molecules to Enhance\nElectro-Optical Characteristics

We have studied the effects of carbon\nquantum dots (CQDs) in a\nwide temperature range room-temperature antiferroelectric liquid crystal\nmixture. Multiple techniques, including Raman, UV–vis Fourier\ntransform infrared spectroscopies, and high-resolution transmission\nelectron microscopy (HRTEM), are used to characterize the synthesized\nCQDs. The HRTEM image indicates the quasi-spherical shape of CQDs\nof particle size 1.0–5.5 nm. Textural and switching characteristics\nof mixture W-287 and its nanocomposites (with CQDs) are investigated\nin the wide temperature range of the antiferroelectric chiral smectic\nC (SmC*<sub>a</sub>) phase and the narrow range of the ferroelectric\nchiral smectic C (SmC*) phase. Observed textures and other switching\ncharacteristics were used to identify the appearance of different\nmesophases. Compared to the pure W-287 AFLC mixture, a drastic increase\nin spontaneous polarization (329 to 706 nC/cm<sup>2</sup>), a substantial\ndecrease of switching time (3 ms to 20 μs), rotational viscosity\n(49 to 7 mPa s), and anchoring energy coefficients for the composite\nsystems were found for the SmC*<sub>a</sub> phase in the present investigation.\nThe observed changes are due to the enhanced dipolar ordering as a\nconsequence of the sp<sup>3</sup>/sp<sup>2</sup> hybridization of\nCQDs, which forms an intense coupling in the liquid crystal matrix.\nThis study signifies that the dispersed CQDs have effectively settled\nin the matrix of the present AFLC mixture without interfering with\nthe hosts’ molecular ordering. These findings are useful for\nthe potential applicability of composite systems for optical devices\nwith a microsecond response.