Low refractive index surface layers and related methods

Patent metadata

Field	Value
Publication number	US-12281384-B2
Application number	US-202318211903-A
Country	US
Kind code	B2
Filing date	Jun 20, 2023
Priority date	Jul 13, 2017
Publication date	Apr 22, 2025
Grant date	Apr 22, 2025

Abstract

The disclosure relates to a method for forming a low refractive index layer on a substrate. The method generally includes (a) applying a block copolymer layer on a substrate, the block copolymer including a polar polymeric block and a non-polar polymeric block; (b) swelling the block copolymer layer with a solvent to increase the block copolymer layer thickness; (c) depositing a metal oxide or metalloid oxide layer on polar polymeric blocks of the block copolymer layer; and (d) removing the block copolymer layer from the substrate, thereby forming a porous metal oxide or metalloid oxide layer on the substrate.

First claim

What is claimed is:

1. An antireflective coated substrate comprising:
(a) a transparent material substrate;
(b) a porous metal oxide or metalloid oxide layer on the transparent material substrate;
wherein the porous metal oxide or metalloid oxide layer has an index of refraction (n c ) and a thickness (d c ) selected according to the following relationship:
n c =( n s n m ) 0.5   (I)

d c =λ 0 /(4 n c )  (II)

wherein:
n s is the index of refraction of the transparent material of the substrate;
n m is the index of refraction of the medium through which incident light passes before passing through the formed porous metal oxide or metalloid oxide layer and the transparent material of the substrate;
λ 0 is an incident wavelength to be fully transmitted through the porous metal oxide or metalloid oxide layer and the transparent material of the substrate, λ 0 being a selected single wavelength in range from 250 to 3000 nm;
the index of refraction (n c ) of the porous metal oxide or metalloid oxide layer is within ±0.03 units of the value of n s specified by equation (I);
the thickness (d c ) of the porous metal oxide or metalloid oxide layer is within ±10% of the value of d c specified by equation (II); and
the thickness (d c ) of the porous metal oxide or metalloid oxide layer is in a range from 50 to 1000 n m ; and

wherein the porous metal oxide or metalloid oxide layer is formed on the substrate by:
(a) applying a block copolymer layer on a substrate, the block copolymer comprising a polar polymeric block and a non-polar polymeric block;
(b) completely immersing the block copolymer in a solvent at a temperature ranging from 55° C. to 120° C., thereby swelling the block copolymer layer and increasing the block copolymer layer thickness followed by removing at least 75% of the liquid solvent from the block copolymer layer to provide a dried, swollen, block copolymer;
(c) depositing a metal oxide or metalloid oxide layer on the polar polymeric blocks of the dried, swollen, block copolymer layer; and
(d) removing the block copolymer layer from the substrate, thereby forming the porous metal oxide or metalloid oxide layer on the substrate.

2. The antireflective coated substrate of claim 1 , wherein the transparent material has an index of refraction ranging from 1.3 to 2.5.

3. The antireflective coated substrate of claim 1 , wherein the transparent material is selected from the group consisting of fused glass, crown glass, sapphire glass, alkali-aluminosilicate plate glass, polycarbonate, poly (methyl methacrylate), plate glass, flint glass, and diamond.

4. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide comprises alumina (Al2O3), silica (SiO2), titanium dioxide (TiO2), zinc oxide (ZnO), hafnium dioxide (HfO2), yttrium oxide (Y2O3), or a combination thereof.

5. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide layer has a porosity ranging from 10 to 90 wt. %.

6. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide layer has an index of refraction value 0.05-0.5 less than a corresponding index of refraction for a bulk metal oxide or metalloid oxide material.

7. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide layer has an index of refraction ranging from 1.0 to 2.5.

8. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide layer on the transparent material substrate has an index of refraction within ±0.03 units of the index of refraction of the transparent material substrate.

9. The antireflective coated substrate of claim 1 , further comprising a second porous metal oxide or metalloid oxide layer on the porous metal oxide or metalloid oxide layer, the second porous metal oxide or metalloid oxide layer having an index of refraction within ±0.15 units of the index of refraction of a selected medium external to the antireflective coated substrate.

10. The antireflective coated substrate of claim 1 , wherein the block copolymer is selected from the group consisting of polystyrene-b-polymethylmethacrylate (PS-b-PMMA), polystyrene-b-polyvinylpyridine (PS-b-PVP or PS-b-P4VP for a 4-vinyl pyridine block), polybutadiene-polybutylmethacrylate, polybutadiene-polydimethylsiloxane, polybutadiene-b-polymethylmethacrylate, polybutadiene-b-polyvinylpyridine, polybutadiene-b-polyvinylpyridine, polyethyleneoxide-b-polyisoprene, polyethyleneoxide-b-polybutadiene, polyethyleneoxide-b-polystyrene, polyethylene-b-polyvinylpyridine, polyisoprene-b-polymethylmethacrylate, polyisoprene-b-polyvinylpyridine, polyisobutylene-b-polybutylmethacrylate, polyisobutylene-b-polydimethoxysiloxane, polyisobutylene-b-polymethylmethacrylate, polyisobutylene-b-polyvinylpyridine, polyethylene-b-polymethylmethacrylate, polystyrene-b-polybutylacrylate, polystyrene-b-polybutylmethacrylate, polystyrene-b-polydimethoxysiloxane, polystyrene-b-lactic acid, and combinations thereof.

11. The antireflective coated substrate of claim 1 , wherein
the polar polymeric block is present in the block copolymer in an amount ranging from 10 to 90 wt. %; and
the non-polar polymeric block is present in the block copolymer in an amount ranging from 10 to 90 wt. %.

12. The antireflective coated substrate of claim 1 , wherein the block copolymer has a molecular weight ranging from 20 to 500 kDa.

13. The antireflective coated substrate of claim 1 , wherein the block copolymer layer as applied has a thickness ranging from 10 to 1000 nm.

14. The antireflective coated substrate of claim 1 , wherein the block copolymer layer thickness after swelling relative to the block copolymer layer thickness prior to swelling ranges from 1.1 to 3.

15. The antireflective coated substrate of claim 1 , wherein depositing the metal oxide or metalloid oxide layer comprises performing atomic layer deposition (ALD) (i) to selectively deposit a first precursor on polar polymeric blocks of the block copolymer layer in a first deposition half-cycle, and (ii) to react the deposited first precursor with a second precursor in a second subsequent deposition half-cycle, thereby forming the metal oxide or metalloid oxide layer.

16. The antireflective coated substrate of claim 1 , wherein removing the block copolymer layer from the substrate comprises performing thermal annealing.

17. The antireflective coated substrate of claim 1 , wherein the porous metal oxide or metalloid oxide layer has a porosity ranging from 70 to 90 wt. %.

18. The antireflective coated substrate of claim 1 , wherein n m is 1.0 or 1.33.

19. An antireflective coated substrate comprising:
(a) a transparent material substrate;
(b) a first porous metal oxide or metalloid oxide layer on the transparent material substrate, the first porous metal oxide or metalloid oxide layer having an index of refraction within ±0.03 units of the index of refraction of the transparent material substrate;
(c) a second porous metal oxide or metalloid oxide layer above the first porous metal oxide or metalloid oxide layer as an outer layer for the antireflective coated substrate, the second porous metal oxide or metalloid oxide layer having an index of refraction within ±0.15 units of the index of refraction of a selected medium external to the antireflective coated substrate; and
(d) optionally one or more intermediate porous metal oxide or metalloid oxide layers positioned between the first porous metal oxi

Assignees

• Uchicago Argonne Llc

Inventors

• Shevchenko Elena
• Berman Diana
• Guha Supratik

Classifications

• G02B2207/107

  Porous materials, e.g. for reducing the refractive index · CPC title

• G02B1/118

  having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures · CPC title

• C23C16/45525

  Atomic layer deposition [ALD] · CPC title

• C23C16/04

  Coating on selected surface areas, e.g. using masks · CPC title

• C23C16/045

  Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates · CPC title