US 12,168,827 B2
Light filter coating and method of production
Kimani A. Stancil, Baltimore, MD (US); and James S. Hammonds, New York, NY (US)
Assigned to Howard University, Washington, DC (US)
Filed by HOWARD UNIVERSITY, Washington, DC (US)
Filed on Mar. 1, 2016, as Appl. No. 15/057,927.
Claims priority of provisional application 62/127,193, filed on Mar. 2, 2015.
Prior Publication US 2016/0258049 A1, Sep. 8, 2016
Int. Cl. C23C 24/08 (2006.01); B82Y 30/00 (2011.01); G02B 1/00 (2006.01)
CPC C23C 24/08 (2013.01) [G02B 1/002 (2013.01); B82Y 30/00 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method of applying a filtering coating to a substrate, comprising:
depositing a solution on a surface of a substrate, wherein the solution comprises an organic solvent with nanorods dispersed within the solvent, wherein the nanorods comprise cadmium selenide (CdSe) nanorods;
allowing evaporation of the solution to increase a volume fraction of the nanorods in the solution as a function of the evaporation; and
providing an aligned deposit of the nanorods, as a function of the evaporation, wherein the aligned deposit of nanorods comprises thousands of the nanorods with at least a majority of the nanorods aligned relative to a length of the nanorods;
wherein the organic solvent comprises methylcyclohexane;
wherein the evaporation of the solution induces depositing the aligned nanorods along a periphery of the deposited solution as a periphery of the solution recedes across the substrate during evaporation with the majority of aligned nanorods aligning generally parallel with an exterior perimeter of the deposited solution; and
wherein the nanorods comprise nanorods having an average aspect ratio equal to or greater than 4.8 and equal to or smaller than 15.9, wherein an aspect ratio of each nanorod is defined by a length of the nanorod divided by a width of the nanorod,
wherein the length of the nanorod is 17.9 nm to 56.7 nm, and the width of the nanorod is 3.0 nm to 4.8 nm,
wherein an inverse of solution volume is smaller than 9,
wherein the depositing the solution comprises (i) a drop-casting of the solution using a microchannel, and (ii) measuring an orientational and positional ordering of the nanorods within the microchannel by measuring optical birefringence using a quartz wafer or by measuring Small-angle X-ray scattering (SAXS) using the quartz wafer, the microchannel having a depth/a width of from 0.2 to 0.25,
wherein the evaporation of the solution is induced by flowing a gas over the surface of the substrate at between 80 and 100 feet per minute,
wherein the solvent or the solution is additionally applied to the surface of the substrate during the evaporation, and
wherein a solvent annealing is performed after the step of allowing evaporation of the solution.