Liquid crystal display device

Patent metadata

Field	Value
Publication number	US-2016272889-A1
Application number	US-201415035652-A
Country	US
Kind code	A1
Filing date	Nov 4, 2014
Priority date	Nov 12, 2013
Publication date	Sep 22, 2016
Grant date	—

Abstract

Provided is a liquid crystal display device including first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, thin-film transistors disposed on the first substrate, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The liquid crystal composition contains at least one compound selected from the group consisting of compounds represented by general formulas (LC3) to (LC5) and at least one compound selected from the group consisting of compounds represented by general formulas (II-a) to (II-f).

First claim

1 . A liquid crystal display device comprising:
first and second opposing substrates; a liquid crystal layer comprising a liquid crystal composition between the first and second substrates; a plurality of gate lines and data lines arranged in a matrix on the first substrate; thin-film transistors disposed at intersections of the gate lines and the data lines; and pixel electrodes that are driven by the transistors and that comprise a transparent conductive material, each thin-film transistor comprising a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer, wherein the liquid crystal composition comprises: at least one compound selected from the group consisting of compounds represented by general formulas (LC3) to (LC5):

wherein R LC31 , R LC32 , R LC41 , R LC42 , R LC51 , and R LC52 are each independently an alkyl group of 1 to 15 carbon atoms, wherein one or more —CH 2 — groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen; A LC31 , A LC32 , A LC41 , A LC42 , A LC51 , and A LC52 are each independently any of the following structures:

(wherein one or more —CH 2 — groups in the cyclohexylene group are optionally replaced with oxygen; one or more —CH═ groups in the 1,4-phenylene group are optionally replaced with nitrogen; and one or more hydrogen atoms in the structures are optionally replaced with fluorine, chlorine, —CF 3 , or —OCF 3 ); Z LC31 , Z LC32 , Z LC41 , Z LC42 , Z LC51 , and Z LC51 are each independently a single bond, —CH═CH—, —C≡C—, —CH 2 CH 2 —, —(CH 2 ) 4 —, —COO—, —OCH 2 —, —CH 2 O—, —OCF 2 —, or —CF 2 O—; Z 5 is —CH 2 — or oxygen; X LC41 is hydrogen or fluorine; m LC31 , m LC32 , m LC41 , m LC42 , m LC51 , and m LC52 are each independently 0 to 3; and m LC31 +m LC32 , m LC41 +m LC42 , and m LC51 +m LC52 are each 1, 2, or 3, wherein each occurrence of A LC31 to A LC52 and Z LC31 to Z LC52 , if present, may be the same or different; and
at least one compound selected from the group consisting of compounds represented by general formulas (II-a) to (II-f):

wherein R 19 to R 30 are each independently an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, or an alkenyl group of 2 to 10 carbon atoms; and X 21 is hydrogen or fluorine.

2 . The liquid crystal display device according to claim 1 , wherein the oxide semiconductor layer comprises an oxide containing at least one element selected from In, Ga, Zn, and Sn.

3 . The liquid crystal display device according to claim 1 , wherein the oxide semiconductor layer comprises an oxide containing In, Ga, and Zn.

4 . The liquid crystal display device according claim 1 , wherein the liquid crystal layer further comprises a compound represented by general formula (LC):

wherein
R LC is an alkyl group of 1 to 15 carbon atoms, wherein one or more —CH 2 — groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen;
A LC1 and A LC2 are each independently a group selected from the group consisting of
(a) trans-1,4-cyclohexylene (wherein one or more non-adjacent —CH 2 — groups present in the group are optionally replaced with oxygen or sulfur),
(b) 1,4-phenylene (wherein one or more non-adjacent —CH═ groups present in the group are optionally replaced with nitrogen), and
(c) 1,4-bicyclo(2.2.2)octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, and chromane-2,6-diyl,

wherein one or more hydrogen atoms present in groups (a), (b), and (c) are each optionally replaced with fluorine, chlorine, —CF 3 , or —OCF 3 ;
Z LC is a single bond, —CH═CH—, —CF═CF—, —C≡C—, —CH 2 CH 2 —, —(CH 2 ) 4 —, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, —COO—, or —OCO—;
Y LC is hydrogen, fluorine, chlorine, cyano, or an alkyl group of 1 to 15 carbon atoms, wherein one or more —CH 2 — groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C≡C—, —CF 2 O—, or —OCF 2 — such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen; and
a is an integer of 1 to 4, wherein if a is 2, 3, or 4, each occurrence of A LC1 may be the same or different, and each occurrence of Z LC may be the same or different,
with the proviso that compounds represented by general formulas (LC3), (LC4), (LC5), and (II-a) to (II-f) are excluded.

5 . The liquid crystal display device according to claim 1 , wherein the liquid crystal composition comprises, as the compounds represented by general formulas (LC3), (LC4), and (LC5), at least one compound selected from the group consisting of compounds represented by general formulas (LC3-1), (LC4-1), and (LC5-1):

wherein R 31 to R 33 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; R 41 to R 43 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; Z 31 to Z 33 are each a single bond, —CH═CH—, —C≡C—, —CH 2 CH 2 —, —(CH 2 ) 4 —, —COO—, —OCO—, —OCH 2 —, —CH 2 O—, —OCF 2 —, or —CF 2 O—; X 41 is hydrogen or fluorine; and Z 34 is —CH 2 — or oxygen.

6 . The liquid crystal display device according to claim 1 , wherein the liquid crystal composition comprises, as the compounds represented by general formulas (LC3), (LC4), and (LC5), at least one compound selected from the group consisting of compounds represented by general formulas (LC3-2), (LC4-2), and (LC5-2):

wherein R 51 to R 53 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; R 61 to R 63 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; B 1 to B 3 are each 1,4-phenylene or trans-1,4-cyclohexylene optionally substituted with fluorine; Z 41 to Z 43 are each a single bond, —CH═CH—, —C≡C—, —CH 2 CH 2 —, —(CH 2 ) 4 —, —COO—, —OCO—, —OCH 2 , —CH 2 O—, —OCF 2 —, or —CF 2 O—; X 42 is hydrogen or fluorine; and Z 44 is —CH 2 — or oxygen.

7 . The liquid crystal display device according to claim 1 , wherein the liquid crystal composition forming the liquid crystal layer has a rotational viscosity γ1 of 150 or less, a refractive index anisotropy Δn of 0.08 to 0.13, and a Z of 13,000 or less, wherein Z is represented by the following equation:
Z=γ 1/Δ n 2   [Math. 1]

Assignees

• Dainippon Ink & Chemicals

Inventors

• Ogawa Shinji
• Iwashita Yoshinori

Classifications

• C09K2019/325

  containing a tetrahydronaphthalene, e.g. -2,6-diyl (tetralin) · CPC title

• G02F1/13439

  characterised by their electrical, optical, physical properties; materials therefor; method of making · CPC title

• G02F1/134309

  characterised by their geometrical arrangement · CPC title

• G02F1/133365

  Cells in which the active layer comprises a liquid crystalline polymer · CPC title

• C09K2019/0448

  the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate · CPC title