PHOTO-ALIGNMENT AGENT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME
A photo-alignment agent and a liquid crystal display using the same are provided. A photo-reactive group according to an exemplary embodiment of the present invention includes a first alignment material without a photo-reactive group, a second alignment material including a photo-reactive group, and a photosensitizer mixed with the second alignment material.
1 . A photo-alignment agent comprising:
a first alignment material without a photo-reactive group;
a second alignment material including a photo-reactive group; and
a photosensitizer mixed with the second alignment material.
2 . The photo-alignment agent of claim 1 , wherein
the photosensitizer is an additional material that does not chemically react with the second alignment material.
3 . The photo-alignment agent of claim 2 , wherein
the photosensitizer is one of compounds represented by Formula 1 to Formula 3:
4 . The photo-alignment agent of claim 1 , wherein
the photosensitizer is coupled to the second alignment material after baking the second alignment material.
5 . The photo-alignment agent of claim 4 , wherein
the photosensitizer includes a functional group capable of reacting with the second alignment material.
6 . The photo-alignment agent of claim 5 , wherein
the functional group is one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group.
7 . The photo-alignment agent of claim 6 , wherein
the photosensitizer is one of compounds represented by Formula 4 and Formula 5:
wherein X as a coupler represents —O— or —S—, R may represent an alkyl having 1-15 carbon atoms, and Y may represent an oxirane, —OH, —NH 2 , or —COOH.
8 . The photo-alignment agent of claim 1 , wherein
a first monomer includes the photosensitizer and;
a second monomer includes the second alignment material including the photo-reactive group,
wherein the first monomer and second monomer are copolymerized to form a photo-alignment layer.
9 . The photo-alignment agent of claim 8 , wherein
the first monomer is one of compounds represented by Formula 6 and Formula 7:
wherein X as a coupler represents —O— or —S—, R represents an alkyl having 1-15 carbon atoms, and Y represents —O— or —COO—.
10 . The photo-alignment agent of claim 1 , wherein
the photosensitizer absorbs a wavelength of 200-500 μm from a UV light source that is linearly polarized, thereby transmitting energy to the photo-reactive group.
11 . The photo-alignment agent of claim 1 , wherein
the first alignment material and the second alignment material form an alignment layer having a surface, and a ratio of a mol concentration of the second alignment material to a mol concentration of the first alignment material is increased close to the surface of the alignment layer.
12 . The photo-alignment agent of claim 1 , wherein
the first alignment material and the second alignment material have a weight ratio of 5:95 to 50:50.
13 . The photo-alignment agent of claim 1 , wherein
the second alignment material includes an imide group at a concentration of more than 75 mol %.
14 . A photo-alignment agent comprising
a photo-alignment material including a main chain and a side chain having a photo-reactive group; and
a photosensitizer,
wherein the photo-reactive group includes a compound represented by Formula A:
wherein A and B are independently one of cyclohexane, —CH 2 —, —C 2 H 4 —, dioxane, tetrahydropyran, benzene, naphthalene, and chromane,
X and Y are independently single bonds or —C n H 2n —, where n is an integer of 1 to 12; and
R is hydrogen or an alkyl group with 1-12 carbon atoms.
15 . The photo-alignment agent of claim 14 , wherein
C in the compound represented by Formula A is one of compounds represented by Formula 10 to 13:
wherein LP is a position connected to X.
16 . The photo-alignment agent of claim 14 , wherein
the photosensitizer is an additional material that does not chemically react with the main chain or the photo-reactive group, and is one of compounds represented by Formula 1 to Formula 3:
17 . The photo-alignment agent of claim 14 , wherein
the photosensitizer includes a functional group that is coupled with the main chain after baking the photo-alignment material, and the functional group is one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group.
18 . The photo-alignment agent of claim 14 , wherein
a first monomer includes the photosensitizer;
a second monomer includes the photo-reactive group,
wherein the first monomer and the second monomer are copolymerized to form a photo-alignment layer
19 . A liquid crystal display comprising:
a first substrate;
a second substrate facing the first substrate;
an alignment layer formed on at least one of the first substrate and the second substrate, the alignment layer including
a first alignment material,
a second alignment material having a photo-reactive group, and
a photosensitizer mixed with the second alignment material; and
a liquid crystal layer interposed between the first substrate and the second substrate.
20 . The liquid crystal display of claim 19 , wherein
the photosensitizer absorbs a wavelength of 200-500 μm from a UV light source that is linearly polarized, thereby transmitting energy to the photo-reactive group.
21 . The liquid crystal display of claim 20 , wherein
the photo-reactive group includes a compound represented by Formula A:
wherein A and B are independently one of cyclohexane, —CH 2 —, —C 2 H 4 —, dioxane, tetrahydropyran, benzene, naphthalene, and chromane,
X and Y are independently single bonds or —C n H 2n —, where n is an integer of 1 to 12, and
R is hydrogen or an alkyl group with 1-12 carbon atoms.
22 . The liquid crystal display of claim 19 , wherein
the photosensitizer is an additional material that does not react with the second alignment material, and is one of compounds represented by Formula 1 to Formula 3:
23 . The liquid crystal display of claim 19 , wherein
the photosensitizer includes a functional group that is coupled with the main chain after baking the second alignment material, and the functional group is one of an epoxy group, an amine group, a carboxylic acid group, and an alcohol group.
24 . The liquid crystal display of claim 19 , wherein
the alignment layer is formed by copolymerizing a first monomer including the photosensitizer and a second monomer including the photo-reactive group.
25 . The liquid crystal display of claim 19 , wherein
a ratio of a mol concentration of the second alignment material to a mol concentration of the first alignment material is increased close to the surface of the alignment layer.
26 . The liquid crystal display of claim 19 , further comprising:
a first signal line and a second signal line intersecting each other on the first substrate;
a thin film transistor connected to the first signal line and the second signal line;
a pixel electrode connected to the thin film transistor; and
a common electrode formed on the second substrate.
27 . The liquid crystal display of claim 26 , wherein
the pixel electrode includes a first sub-pixel electrode and a second sub-pixel electrode.
28 . The liquid crystal display of claim 27 , wherein
the second sub-pixel electrode includes:
a first electrode piece disposed, in a layout view, above the first sub-pixel electrode;
a second electrode piece disposed, in a layout view, under the first sub-pixel electrode and connected to the first sub-pixel electrode; and
a plurality of bridges connecting the first electrode piece and the second electrode on, in a layout view, right and left sides of the first sub-pixel electrode.