Aligning Liquid Crystal Materials through Nanoparticles: A Review of Recent Progress

Abstract

Liquid crystals (LCs) have become indispensable materials in everyday life, with their applications ranging from high-resolution television displays to being a part of sophisticated and modern equipment for telecommunications and sensing purposes. Various important features of LC-based devices such as their response time, driving voltage, contrast ratio and brightness are controlled by the uniform alignment of the constituting molecules along the substrate surface. This alignment control can be achieved through various mechanical and non-mechanical techniques. Nanoparticles (NPs), which have become an underbelly of the latest technological developments, can also be incorporated into these tunable materials in order to achieve the desired alignment in them. The present review highlights the advantages of NPs -induced alignment technique over the other contemporary techniques available for aligning LCs. The NPs-induced alignment process is found to be cost-effective and reliable, and it does not require extreme physical conditions such as a low pressure for its operation. This alignment process enables manufacturers to effectively control the pretilt angle of the LC molecules by simply varying the concentration of the doped NPs in the host LC matrix. Furthermore, the alignment behavior in LCs is found to be a function of shape, size, concentration and solubility of the doped NPs in these materials. At the end, this review focuses on the methodology of developing new innovative devices based on this alignment process. With the fabrication of new NPs of different morphologies in recent times, the horizon of the LC nanoscience field is continuously increasing, thus paving way for new devices capitalizing on this alignment technique.