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Abstract— We have developed an effective method for liquid‐crystal alignment of the large‐area substrates. This method is based on the oblique treatment of the alignment substrates with a “sheet” of accelerated plasma generated by the anode layer source of the “race track” geometry. During this treatment, the substrate or source is cyclically translated in the direction perpendicular to the plasma “sheet.” This method provides planar, tilted, and vertical liquid‐crystal alignment with excellent uniformity and reproducibility and easy axis control in the azimuthal and polar planes.

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We studied temporal degradation (aging) of liquid crystal (LC) alignment on plasma beam processed substrates using LC pretilt angle as a measure of this process. It was shown that aging may manifest itself either in pretilt angle decay or pretilt angle growth depending on LC and alignment material. The alteration of electro-optic curves due to alignment aging was revealed. The weakest aging effect was observed for inorganic alignment layers obtained by PECVD method. An important reason of aging is chain scission and generation of low molecular weight reactive species disturbing surface anisotropy of atomic bonds and anisotropy of surface topology.

In this paper, we present the new results related to LC alignment on the substrates obliquely treated with a “sheet” of accelerated Ar+ plasma generated by an anode layers thruster (ALT). The substrates of organic (polymers) and inorganic (glass, DLC, SiO2, etc.) origin were treated with the plasma flux in static and dynamic regime (unidirectional translation perpendicularly to plasma “sheet”). For LCs with Δ∍<0, in both regimes, we observed two aligning modes, with the easy axis confined to the plane of plasma incidence (mode 1) or perpendicular to this plane (mode 2). In the 1st aligning mode the LC pretilt angle is not equal to zero and can be varied with the incidence angle of plasma beam and the irradiation dose. The uniformity of pretilt angle is better in the dynamic regime. With the increase of irradiation dose, the alignment transition from the 1st to the 2nd mode occurs. For the LC mixtures with Δ∍<0, used for VA LCD, only the 1st mode alignment (uniform over the whole substrate) is realized. It occurs at low and even at the relatively high irradiation doses, which cause the 2nd mode alignment for the LCs with δ∍>0. The pretilt angle achieves values as high as 30° and can be controlled by the irradiation dose and by the incidence angle of plasma beam. The 2nd alignment mode is observed at high irradiation doses and only in the static regime of irradiation. It occurs in the central, most intensive part, of the plasma “sheet”, while the periphery part shows the 1st mode. The areas of the 1st and the 2nd mode are separated with the narrow transition area showing multidomain (two‐fold degenerate) LC alignment. The easy axis in these domains is turned by about ±45° with respect to the alignment direction in the 1st mode area. The alignment transition 1st mode — two‐fold degenerate alignment — 2nd mode observed for LC with δ∍<0 is quite similar to the one earlier described for vapor deposition alignment. In the dynamic irradiation regime, for both types of LC, uniform alignment on the substrates as big as 15×15 cm is realized.