Polyhedral oligomeric silsesquioxane nanoparticles: an effective dopant for homeotropic alignment of liquid crystals with enhanced electro-optic performance

Hybrid nanoparticles (NPs), especially polyhedral oligomeric silsesquioxane (POSS) NPs, have emerged as efficient dopants for enhancing the electro-optic (EO) performance of liquid crystal (LC) devices. POSS NPs improve homeotropic alignment (HA) stability, reduce applied voltages, decrease ion density, and optimize dielectric properties, etc., leading to significant performance gains. In the present review, the analysis of reported EO studies shows a reduction in threshold (V_th) and operating (V_O) voltages by up to 25–35% and 20–30%, respectively, along with an enhanced contrast ratio (CR) of 40–60%. In addition, the response times improve markedly, with rise and fall times shortened by 20–50% compared with the undoped systems. Moreover, the dielectric anisotropy (Δε), conductivity suppression, and elastic constants are also favourably tuned. These improvements arise from POSS–LC molecular interactions and surface anchoring effects, which make the POSS-doped LC system potentially applicable to advanced displays, fast switching spatial light modulators (SLMs), tunable photonic devices, and low power EO components. Thus, the present work consolidates recent findings, provides comparative quantitative analysis, and highlights future opportunities for POSS-based nanocomposites in next-generation LC technologies.