Faculty of Physics - University of Bucharest

UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-23 18:11

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Conference: Bucharest University Faculty of Physics 2023 Meeting

Section: Polymer Physics

Title:

Electro-optical switching of plasma deposited PANI layered liquid crystal cells

Authors:

Bogdan BUTOI(1), Andreea GROZA(1), Paul DINCA(1), Cornel STAICU(1,2,3), Oana POMPILIAN(1), Cristian LUNGU(1) and Valentin BARNA(3)

^*
Affiliation:

1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele, Romania

2) Doctoral Scholl of Physics, University of Bucharest,90 Panduri Street, Bucharest, Romania

3) Faculty of Physics, University of Bucharest, 405 Atomistilor Street, Magurele, Romania

E-mail

bagdan.butoi@inflpr.ro

Keywords:

plasma, plasma polymerization, polymers, liquid crystal, response time

Abstract:

The most common application of liquid crystals is in the manufacture of displays,industry that exceeds several billion dollars.Currently, liquid crystal display manufacturing techniques and technology are low in price and high in reliability, so hundreds of millions devices are made, especially in the Far East and Japan. This technology has had a resounding success especially due to the "passive" nature of the operation, low energy consumption and good clarity in strong lighting. For displays to be effective, the refresh rate of a display must be greater that the refresh rate of the human eye (30-60Hz). These refresh rates are easily obtained with colesteric liquid crystals but are more expensive than nematic liquid crystals most commonly used. In this work, by means of a DC plasma polymerization reactor, we depositedpolyaniline (PANI) thin films on top of ITO coated glass, at different plasma and geometrical parameters, to obtain different topologies in order to condition nematic liquid crystals to behave like colesteric ones. Morphological measurements were performed by AFM and SEM imaging, while structural proprieties were investigated by FT-IR. 6 of the coated samples was used to obtain liquid crystal cells(LCC) and filled with nematic crystals. The refresh rate of each LCC was measured using an electro-optical setup in two different configurations (ground switch-off from polymer side / ITO side) and at different polarization voltages and frequencies.

References:

[1] Butoi, B.; Groza, A.; Dinca, P.; Balan, A.; Barna, V. Morphological and Structural Analysis of Polyaniline and Poly(o-anisidine) Layers Generated in a DC Glow Discharge Plasma by Using an Oblique Angle Electrode Deposition Configuration. Polymers 2017, 9, 732. https://doi.org/10.3390/polym9120732

[2] B. BUTOI, D. STAICU,Cured Pmma Thin Films For Greatly Improving The Electrooptical Response Time In Nematic Liquid Crystal Pixels, Digest Journal of Nanomaterials and Biostructures Vol. 14, No. 1, January - March 2019, p. 175 - 182.