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We report a Liquid Crystal Display (LCD) structure employing cellulose nanocrystals (CNC) as a recyclable, non‐toxic alignment layer in a twisted nematic configuration The CNC alignment layer, fabricated via spin coating and mechanical rubbing, demonstrated comparable performance to polyimide in transparency, threshold voltage, response speed, and liquid crystal alignment This work demonstrates the viability of CNC alignment layers, advancing LCD technology toward circular economy principles.
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This content will become publicly available on November 13, 2025
Carbon dots induced homeotropic alignment in a negative dielectric nematic liquid crystal material
Abstract Recently, doping guest materials such as quantum dots (QDs) into liquid crystals (LCs) has been of great interest since their addition substantially enhances the properties of LC and opens new avenues for scientific advancement. Here, we report the induction of homeotropic alignment in cells without alignment layers of the negative dielectric nematic liquid crystal, N-(4-Methoxybenzylidene)-4-butylaniline (MBBA) by doping with carbon dots (CDs ∼2.8 ± 0.72 nm). The CDs-MBBA composites (CDs concentration: 0.002, 0.01, 0.03, 0.1 and 0.3 wt%) were investigated using optical polarising microscopy, electro-optical and dielectric techniques. Polarizing optical micrographs and voltage dependent optical transmission revealed the induced homeotropic alignment for all the composites under investigation. Interestingly, the least concentrated sample, 0.002 wt% exhibited partial homeotropic alignment. However, due to light leakage, the optical transmission value below threshold voltage was relatively higher than the rest of the composites. MBBA is a negative dielectric material, hence the application of a voltage across the cell was able to switch the alignment from a dark to a bright state for all composites. However, above a certain voltage (>threshold voltage), the bright state produced some instabilities. The value of dielectric permittivity was observed to decrease with increasing concentration, confirming the effect of CDs in producing homeotropic alignment in MBBA. Measurements as a function of temperature were conducted to examine the thermal stability of the induced alignment. The alignment was found to be stable throughout the nematic phase of MBBA. The induction of such alignment without conventional alignment (i.e., rubbing of polyimides) technique can be helpful in addressing the evolving display demands by making liquid crystal displays (LCDs) and other display devices cost effective.
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- Award ID(s):
- 2211347
- PAR ID:
- 10616062
- Editor(s):
- Di_Bartolomeo, Antonio
- Publisher / Repository:
- IOP Science
- Date Published:
- Journal Name:
- Nano Express
- Volume:
- 5
- Issue:
- 4
- ISSN:
- 2632-959X
- Page Range / eLocation ID:
- 045008
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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