Conjugated polymer dotsstabilized blue phase liquid crystal for improved electro-optic and photoluminescence properties

Abstract

Blue-phase liquid crystals (BPLCs) have emerged as essential materials for soft photonic applications. BPLCs exhibit the electro-optic Kerr effect, submillisecond response, and selective reflection properties. However, the narrow temperature width, large hysteresis, and residual birefringence constrain their practical utility. Here, we systematically investigate the thermal and electro-optic stability of BPLC while incorporating conjugated polymer dots (Pdots) at several doping concentrations. We analyzed the phase transition, Kerr constant, threshold voltage, operating voltage, hysteresis, residual birefringence, and response time in pure and doped samples. The selective reflection and photophysical properties are also studied. A minimal doping concentration of Pdots greatly reduced the hysteresis and residual birefringence, along with extension in the thermal range. The selective reflection spectra suggest BPLC lattice contraction with increasing doping concentration. Doping increases lattice rigidity and impacts the electro-optic dynamics of BPLC. This affects the rise–fall time as well as threshold and operating voltages in doped BPLCs. The increased photoluminescence intensity in doped BPLCs suggests an increment in radiative channels, as confirmed through time-resolved photoluminescence spectroscopy. The obtained features signify synergistic effects between Pdots and BPLC. The work captures the unique attributes of Pdots-doped BPLCs, which assimilates the prior studies on inorganic nanoparticles-doped BPLCs and also polymer-stabilized BPLCs.