Dispersion of nanoparticles into the low birefringent nematic liquid crystal: study of optical and electro-optical param
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RESEARCH
Dispersion of nanoparticles into the low birefringent nematic liquid crystal: study of optical and electro‑optical parameters and its applicability towards liquid crystal displays Govind Pathak1,2 · Garima Shukla2 · Atul Srivastava2 · Olga Strzezysz3 · Rajiv Manohar2 Received: 27 July 2020 / Accepted: 10 November 2020 © Islamic Azad University 2020
Abstract In the present reported work, TiO2 nanoparticles (NPs) are dispersed into the pure nematic liquid crystal (NLC) in three different concentrations. The used NLC consisted of 4′-(trans, trans-4-alkylbicyclohexyl) carbonates and 4′-(4-(trans, trans4-alkyl)-4-cyanobicyclohexane, which is an optically sensitive material. Optical parameters like photoluminescence and UV absorbance for this material can be tuned by doping of TiO2 NPs. Study of photoluminescence parameter is crucial for liquid crystalline materials. Therefore, optical and electro-optical parameters are measured here for pure and NP-dispersed NLC system. UV absorbance was found to be decreased for the TiO2-dispersed system when compared to pure NLC. Band gap was also calculated by using Tauc plot method, and it is found to be decreased for the NP-dispersed system. Photoluminescence study revealed that PL intensity increases after the dispersion of NPs into the pure NLC. This is the key output of the present reported work. Response time measurement was measured by Optical Switching method, and it is found to be reduced for NP-dispersed system when compared to pure NLC. Contrast ratio of the NP-dispersed system was also found to be increased. Threshold voltage showed that it decreases after the dispersion of NPs into the pure NLC. Enhanced photoluminescence, fast optical response time and high contrast ratio are the promising results of the present reported work because these parameters have many applications in the liquid crystal displays, opto-electronics devices and photonic devices. Keywords Nanoparticles · Nematic liquid crystal · UV absorbance · Photoluminescence · Response time
Introduction Liquid crystalline materials are highly sensitive to optical environments. These are nonlinear optical materials. Liquid crystals (LCs) have many phases in which nematic liquid crystals (NLCs) are the most important and common type of liquid crystals. NLCs have electrically controllable property since NLCs can be easily controlled by electrical field; * Govind Pathak [email protected] Rajiv Manohar [email protected] 1
Centre for Nano and Soft Matter Sciences, P.B. No. 1329, Jalahalli, Bengaluru 560 013, India
2
Liquid Crystal Research Lab, Department of Physics, University of Lucknow, Lucknow 226007, India
3
Liquid Crystal Group, Military University of Technology, S. Kaliskiego 2, 00‑908 Warsaw, Poland
therefore, due to the specific features, it has a wide range of applications including various electro-optical devices such as LC displays (LCDs), phase modulator and switchable grating etc. It is important to achieve the fast response time and reduced driving voltage of
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