Short-chain fluorosurfactants with iodide additives for forming silver nanowire-based transparent conductive films
Disclosed herein are purified surfactant formulations including purified short-chain fluorosurfactant and iodide additive and a two-part coating kit having the same and a silver nanowire formulation.
1. A method comprising:
providing a coating composition on a substrate, the coating composition comprising:
from 0.05% to 1.4% by weight of conductive nanostructures;
from 0.02% to 4% by weight of a viscosity modifier;
from 94.5% to 99.0% by weight of a liquid carrier; and
from 0.0025% to 0.1% by weight of a purified surfactant formulation comprising:
(1) a short-chain fluorosurfactant represented by Formula (I):
(2) an impurity represented by Formula (II) at an amount of less than about 3% by weight of the short-chain fluorosurfactant,
and
(3) an iodide additive providing iodide at an amount of about 0.5-2.5% by weight of the short-chain fluorosurfactant, wherein:
m is 0, 1, 2, 3, 4, 5, or 6;
n is 1, 2, 3, or 4;
X is —O—,—S—, or a direct bond;
Y is hydrogen,—OH, or fluoro;
Z is —CH 3 ,—CH 2 F,—CHF 2 , or —CF 3 ;
M + is Li + , Na + , K + , H + , or NH 4 ; and
R 1 , R 2 , R 3 , R 4 and R 5 , at each occurrence, are the same or different and independently fluoro or hydrogen; and
drying the coating composition to form a conductive network layer.
2. The method of claim 1 , wherein the impurity represented by Formula (II) is less than about 0.4% by weight of the short-chain fluorosurfactant.
3. The method of claim 1 , wherein the iodide in the purified surfactant formulation is about 0.6-2.4% by weight of the short-chain fluorosurfactant.
4. The method of claim 1 , wherein the conductive nanostructures comprise silver nanowires.
5. The method of claim 1 , wherein the short-chain fluorosurfactant represented by Formula (I) has no more than 6 fluoro-bearing carbons.
6. The method of claim 1 , wherein X is the direct bond.
7. The method of claim 1 , wherein Y is —OH.
8. The method of claim 1 , wherein Z is —CF 3 .
9. The method of claim 1 , wherein m is 6 and n is 2.
10. The method of claim 4 , wherein the silver nanowires are no more than 30 nm in diameter and are more than 5 μm long.
11. The method of claim 1 , further comprising forming an overcoat layer on the conductive network layer.
12. The method of claim 1 , further comprising bonding the conductive network layer to a layer with an optically clear adhesive.
13. The method of claim 1 , further comprising laminating the conductive network layer at a pressure.
14. The method of claim 1 , wherein providing the coating composition on the substrate comprises a roll-to-roll coating.
15. A layer comprising:
a conductive network of nanowires;
a viscosity modifier; and
a short-chain fluorosurfactant represented by Formula (I):
wherein:
m is 0, 1, 2, 3, 4, 5, or 6;
n is 1, 2, 3, or 4;
X is —O—, —S—, or a direct bond;
Y is hydrogen, —OH, or fluoro;
Z —CH 3 , —CH 2 F, —CHF 2 , or —CF 3 ;
M + is Li + , Na + , K + , H + , or NH 4 + ; and
R 1 , R 2 , R 3 , R 4 , and R 5 , at each occurrence, are the same or different and independently fluoro or hydrogen.
16. The layer of claim 15 , further comprising an overcoat or an optically clear adhesive.
17. The layer of claim 15 , wherein a light transmission of the layer is at least 80%.
18. The layer of claim 15 , wherein a haze of the layer is no more than 2%.
19. The layer of claim 15 , wherein the nanowires comprise silver nanowires.
20. An optical stack comprising the layer of claim 15 .