US 11,725,275 B2
Low refractive index surface layers and related methods
Elena Shevchenko, Riverside, IL (US); Diana Berman, Lemont, IL (US); and Supratik Guha, Lemont, IL (US)
Assigned to UCHICAGO ARGONNE, LLC, Chicago, IL (US)
Filed by UCHICAGO ARGONNE, LLC, Chicago, IL (US)
Filed on Jul. 13, 2017, as Appl. No. 15/649,448.
Prior Publication US 2019/0017166 A1, Jan. 17, 2019
Int. Cl. C23C 16/40 (2006.01); C23C 16/455 (2006.01); C23C 16/56 (2006.01); G02B 1/111 (2015.01); C23C 16/04 (2006.01); G02B 1/118 (2015.01)
CPC C23C 16/40 (2013.01) [C23C 16/04 (2013.01); C23C 16/045 (2013.01); C23C 16/403 (2013.01); C23C 16/405 (2013.01); C23C 16/45525 (2013.01); C23C 16/45527 (2013.01); C23C 16/45555 (2013.01); C23C 16/56 (2013.01); G02B 1/111 (2013.01); G02B 1/118 (2013.01); G02B 2207/107 (2013.01)] 30 Claims
OG exemplary drawing
 
1. A method for forming a low refractive index layer on a substrate, the method comprising:
(a) applying a block copolymer layer on the substrate, the block copolymer comprising a polar polymeric block and a non-polar polymeric block, and heating the substrate and block copolymer to induce microphase separation thereby providing a microphase separated block copolymer;
(b) completely immersing the microphase separated block copolymer in a liquid consisting of 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 form the block copolymer layer to provide a dried, swollen, block copolymer;
(c) depositing a metal oxide or metalloid oxide layer on the polar polymeric block of the dried, swollen, block copolymer layer, comprising reacting a gas phase chemical precursor with at least a portion of the surface of the dried, swollen, 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 as the low refractive index layer;
wherein the ratio of the thickness of the block copolymer in step (c) relative to the thickness of the block copolymer layer in step (a) is in a range of 1.1 to 3;
wherein the porous metal oxide or metalloid oxide layer has a thickness of at least 70 nm and a porosity of at least 65%; and
wherein the porous metal oxide or metalloid oxide layer has an index of refraction at least 0.3 lower than the refractive index of the metal oxide or metalloid oxide when provided as a bulk material.