Organic solid crystals having helical structures formed using cholesteric liquid crystals
An optical film includes a plurality of helically arranged liquid crystals and organic solid crystal structures at least partially surrounding the plurality of helically arranged liquid crystals. A method of making the optical film includes obtaining a substrate with an alignment layer and a film of a first solution on the alignment layer. The first solution includes liquid crystals and organic crystal molecules. The liquid crystals form a plurality of helically arranged liquid crystals on the alignment layer. The method also includes forming organic solid crystal structures by crystallizing the organic crystal molecules. The organic solid crystal structures at least partially surround the plurality of helically arranged liquid crystals.
1. An optical film, comprising:
a plurality of helically arranged liquid crystals; and
organic solid crystal structures laterally surrounding the plurality of helically arranged liquid crystals.
2. The optical film of claim 1 , wherein the organic solid crystal structures conform to shapes of the plurality of helically arranged liquid crystals.
3. The optical film of claim 1 , wherein the organic solid crystal structures define a plurality of helically shaped cavities, in which the plurality of helically arranged liquid crystals is located.
4. The optical film of claim 1 , wherein an index of refraction of the optical film is at least 1.9.
5. The optical film of claim 1 , wherein the organic solid crystal structures include one or more polycyclic aromatic hydrocarbons selected from a group consisting of naphthalene, anthracene, tetracene, pentacene, pyrene, polycene, fluoranthene, benzophenone, benzochromene, benzil, benzimidazole, benzene, hexachlorobenzene, nitropyridine-N-oxide, benzene-1,4-dicarboxylic acid, diphenylacetylene, N-(4-nitrophenyl)-(s)-prolinal, 4,5-dicyanoimidazole, benzodithiophene, cyanopyridine, thienothiophene, stilbene, azobenzene, and their derivatives.
6. The optical film of claim 1 , wherein the organic solid crystals include one or more organic ring structures that include (i) one or more saturated cyclic compounds selected from a group consisting of cyclohexane, cyclopentane, tetrahydropyran, piperidine, tetrahydrofuran, pyrrolidine, tetrahydrothiophene and their derivatives and (ii) one or more unsaturated aromatic compounds selected from a group consisting of benzene, naphthalene, anthracene, thiophene, bi-phenyl, tolane, benzimidazole, diphenylacetylene, cyanopyridine, thienothiophene, dibenzothiophene, carbazole, silafluorene and their derivatives.
7. The optical film of claim 6 , wherein the one or more organic ring structures are coupled with one or more terminal groups selected from the group consisting of C 1 -C 10 alkyl, alkenyl, —CN, —NCS, —SCN, —SF 5 , —Br, —Cl, —F, —OCF 3 , —CF 3 , mono- or polyfluorinated C 1 -C 10 alkyl, and alkoxy.
8. The optical film of claim 1 , wherein the plurality of helically arranged liquid crystals includes one or more liquid crystals selected from the group consisting of:
wherein:
R is independently selected from the group consisting of: H or (CH 2 ) n1 CH 2 X 1 ; and
R 1 is independently selected from the group consisting of: H or (CH 2 ) n2 CH 2 X 1 , where X 1 is acrylate, methacrylate, vinyl acrylate, or H, wherein n 1 and n 2 ranges from zero to eight.
9. The optical film of claim 1 , wherein the plurality of helically arranged liquid crystals includes one or more liquid crystals selected from the group consisting of:
wherein
10. The optical film of claim 1 , wherein the plurality of helically arranged liquid crystals includes one or more non-cholesteric liquid crystals and chiral dopants.
11. The optical film of claim 10 , wherein the non-cholesteric liquid crystals are selected from the group consisting of:
R 4 -A-[L 1 ]-B-[L 2 ]-C-[L 3 ]-D-R 5 , wherein:
R 4 and R 5 are terminal groups selected from R′, R′O, CN, NCS, CF 3 , F, Cl, NO 2 , alkenyl, OO═C—CH 3 ═CH 2 , OO═C—CH═CH 2 , wherein R′ in C n H 2n+1 ;
A, B, C, and D are individually selected from the group consisting of:
and L 1 , L 2 , and L 3 are individually selected linking groups selected from the group consisting of: a carbon single bond, a carbon double bond, a carbon triple bond, —COO—, CH 2 CH 2 , CH 2 O—, —CH═N—, —N═N—, and —N(O)═N—.
12. The optical film of claim 10 , wherein the plurality of helically arranged liquid crystals includes one or more non-cholesteric liquid crystals selected from the group consisting of:
wherein:
R 6 is selected from C n H 2n+1 and C n H 2n+1 O; and
X 3 is a terminal group selected from R′, R′O, CN, NCS, CF 3 , F, Cl, NO 2 , alkenyl, OO═C—CH 3 ═CH 2 , OO═C—CH═CH 2 , wherein R′ is C n H 2n+1 .
13. The optical film of claim 10 , wherein the chiral dopants are selected from the group consisting of:
14. The optical film of claim 1 , wherein the plurality of helically arranged liquid crystals are polymerized.
15. The optical film of claim 1 , wherein the optical film has a first surface and an opposing second surface, and the plurality of helically arranged liquid crystals extend from the first surface to the second surface about an axis normal to the first surface.
16. The optical film of claim 1 , wherein the organic solid crystal structures have a first surface and an opposing second surface, and the plurality of helically arranged liquid crystals extend from the first surface to the second surface about an axis normal to the first surface.
17. The optical film of claim 1 , wherein the optical film is a polarization selective and wavelength selective optical film.
18. The optical film of claim 1 , wherein an index of refraction of the organic solid crystal structures is at least 1.9.