Optically anisotropic film stack including solid crystal and fabrication method thereof

Patent metadata

Field	Value
Publication number	US-2022082749-A1
Application number	US-202117363982-A
Country	US
Kind code	A1
Filing date	Jun 30, 2021
Priority date	Sep 15, 2020
Publication date	Mar 17, 2022
Grant date	—

Abstract

A film stack includes a plurality of first films and a plurality of second films alternately stacked. At least one second film of the plurality of second films includes a solid crystal including crystal molecules aligned in a predetermined alignment direction. At least one first film of the plurality of first films includes an alignment structure configured to at least partially align the crystal molecules of the solid crystal in the predetermined alignment direction.

First claim

What is claimed is:

1 . A film stack, comprising:
a plurality of first films and a plurality of second films alternately stacked, wherein at least one second film of the plurality of second films includes a solid crystal including crystal molecules aligned in a predetermined alignment direction, and wherein at least one first film of the plurality of first films includes an alignment structure configured to at least partially align the crystal molecules of the solid crystal in the predetermined alignment direction.

2 . The film stack of claim 1 , wherein the solid crystal is an organic solid crystal.

3 . The film stack of claim 1 , wherein the at least one first film includes an anisotropic organic material, an anisotropic inorganic material, an isotropic organic material, or an isotropic inorganic material.

4 . The film stack of claim 1 , wherein the at least one second film has a higher in-plane optical anisotropy than the at least one first film.

5 . The film stack of claim 1 , wherein
a first in-plane optical anisotropy of the at least one first film is smaller than 0.1, smaller than 0.08, smaller than 0.05, or smaller than 0.03, and a second in-plane optical anisotropy of the at least one second film is at least 0.2, at least 0.25, at least 0.3, at least 0.35, at least 0.4, at least 0.45, or at least 0.5.

6 . The film stack of claim 1 , wherein
a first refractive index difference between a first in-plane refractive index of the at least one second film and a first in-plane refractive index of the at least one first film is at least 0.2, at least 0.25, at least 0.3, at least 0.35, at least 0.4, at least 0.45, or at least 0.5, and a second refractive index difference between a second in-plane refractive index of the at least one second film and a second in-plane refractive index of the at least one first film is smaller than 0.1, smaller than 0.08, smaller than 0.05, or smaller than 0.03.

7 . The film stack of claim 1 , wherein the alignment structure includes at least one of a photosensitive material, a polymer, an amorphous polymer, liquid crystalline, a liquid crystalline polymer, an amorphous inorganic material, or a crystalline inorganic material.

8 . The film stack of claim 1 , wherein the solid crystal is in a form of a continuous layer.

9 . The film stack of claim 1 , wherein
the plurality of second films include a plurality of solid crystals disposed in a stacked configuration, and the plurality of first films include a plurality of alignment structures disposed between the solid crystals.

10 . The film stack of claim 1 , wherein the solid crystal is optically anisotropic with a principal refractive index of at least 1.5 and an optical anisotropy of at least 0.1, the principal refractive index being a refractive index in a direction parallel to an axis of the solid crystal, and the axis of the solid crystal being an axis along which the solid crystal has a highest refractive index.

11 . The film stack of claim 1 , further comprising a plurality of third films alternately stacked with the first films and the second films.

12 . The film stack of claim 11 , wherein at least one of the plurality of third films includes an anisotropic organic material, an anisotropic inorganic material, an isotropic organic material, or an isotropic inorganic material.

13 . The film stack of claim 1 , wherein the alignment structure includes a hexagonal boron nitride or graphene layer.

14 . The film stack of claim 1 , wherein the at least one second film is uniaxially or biaxially anisotropic.

15 . The film stack of claim 1 , wherein the film stack is configured to function as a reflective polarizer to selectively transmit a light with a first polarization, and selectively reflect a light with a second polarization orthogonal to the first polarization.

16 . A method, comprising:
providing a first alignment structure on a surface of a substrate; forming a first solid crystal on the first alignment structure, the first solid crystal including first crystal molecules aligned in a first alignment direction; providing a second alignment structure on the first solid crystal; and forming a second solid crystal on the second alignment structure, the second solid crystal including second crystal molecules aligned in a second alignment direction, wherein refractive indices of the first solid crystal and the first alignment structure in a first in-plane direction are different.

17 . The method of claim 16 , wherein refractive indices of the first solid crystal and the first alignment structure in a second in-plane direction orthogonal to the first in-plane direction are substantially the same.

18 . The method of claim 16 , wherein providing the first alignment structure on the surface of the substrate includes one of:
forming an alignment layer on the substrate through a wet deposition or a vapor phase deposition; or forming an anisotropic relief directly on the substrate through a particle beam treatment.

19 . The method of claim 16 , wherein forming the first solid crystal on the first alignment structure includes:
forming the first solid crystal on the first alignment structure through a wet deposition or a vapor phase deposition.

20 . The method of claim 16 , wherein providing the second alignment structure on the first solid crystal includes one of:
forming an alignment layer on the first solid crystal through a vapor phase deposition; or forming an anisotropic relief directly on the first solid crystal through a particle beam treatment.

Assignees

• Facebook Tech Llc

Inventors

• Malhotra Tanya
• Rao Tingling
• Diaz Liliana Ruiz
• Yaroshchuk Oleg
• Ye Sheng
• Ouderkirk Andrew John
• Koshelev Alexander
• Purvis Ii Lafe Joseph
• Wang Junren
• Boromand Arman

Classifications

• C09K2323/035

  Ester polymer, e.g. polycarbonate, polyacrylate or polyester · CPC title

• C09K2323/031

  Polarizer or dye · CPC title

• C09K2323/03

  Viewing layer characterised by chemical composition · CPC title

• G02B5/3041 Primary

  comprising multiple thin layers, e.g. multilayer stacks · CPC title

• G02B5/3016

  involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528) · CPC title