Display screen and its manufacturing process

Abstract

The invention relates to a display screen and its manufacturing process. The display screen of the invention comprises: a substrate made of a plastic; at least one transparent heating element; and at least one thermochromic compound, and is characterized in that the at least one transparent heating element comprises at least one optionally functionalized metal nanowire. The invention in particular has applications in the electronics industry.

Claims

1. A display screen, comprising: a substrate made of a plastic material; at least one transparent heating element; and at least one thermochromic compound, wherein said at least one transparent heating element comprises at least one metal nanowire which is functionalized and comprises, at an external surface, a self-assembled monomolecular layer formed from one or more precursor of molecule of formula I,
R.sup.1Z.sub.nR.sup.2 Formula I in which: Z represents a sulfur or selenium atom, n=I or 2, R.sup.1 and R.sup.2 each represent, independently of one another, a hydrogen atom or a saturated or unsaturated and linear, branched or cyclic hydrocarbon group which is optionally perfluorinated or partially fluorinated, which comprises from 1 to 100 carbon atoms and which optionally comprises one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom and/or one or more aromatic or heteroaromatic groups, or a chemical functional group comprising at least one heteroatom or one aromatic or heteroaromatic group which is substituted or unsubstituted.

2. The display screen according to claim 1, wherein the self-assembled monomolecular layer completely covers an external surface of the at least one metal nanowire.

3. A method for the manufacture of a display screen, said method comprising: depositing, over all or part of a surface of a substrate made of a plastic material, of at least one heating element comprising at least one metal nanowire, the nanowire being functionalized by formation of a self-assembled monomolecular layer from at least one molecule of formula I,
R.sup.1Z.sub.nR.sup.2 Formula I in which: Z represents a sulfur or selenium atom, n=1 or 2, R.sup.1 and R.sup.2 each represent, independently of one another, a hydrogen atom or a saturated or unsaturated and linear, branched or cyclic hydrocarbon group which is optionally perfluorinated or partially fluorinated, which comprises from 1 to 100 carbon atoms and which optionally comprises one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom and/or one or more aromatic or heteroaromatic groups, or a chemical functional group comprising at least one heteroatom or one aromatic or heteroaromatic group which is substituted or unsubstituted.

4. The display screen according to claim 1, wherein the at least one functionalized metal nanowire comprises a metal chosen from silver, gold, copper, platinum, palladium, nickel, cobalt, rhodium, iridium, ruthenium, and iron.

5. The display screen according to claim 1, wherein in formula I, R.sup.1 is H, Z is S, and R.sup.2 is a saturated C.sub.3 to C.sub.18 alkyl chain or a substituted or unsubstituted C.sub.4 to C.sub.10 aromatic group.

6. The display screen according to claim 1, wherein formula I is one or more selected from 1-propanethiol, 1-decanethiol, 1-octadecanethiol, benzenethiol, 4-methoxybenzenethiol, and 4-trifluoromethylbenzenethiol.

7. The display screen according to claim 1, wherein at least one thermochromic compound is chosen from crystal violet lactone, vanadium dioxide, and mixtures thereof.

8. The display screen according to claim 1, wherein the substrate made of a plastic material is chosen from polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), and a silicone.

9. The display screen according to claim 1, wherein the substrate has a thickness of from 2 m and 500 m.

10. The display screen according to claim 1, further comprising an encapsulation layer, said layer comprising a material chosen from an ethylene/vinyl acetate (EVA) polymer, a vinyl butyral polymer (PVB), and a urethane polymer.

11. The display screen according to claim 1, wherein the substrate is coated with an insulation layer.

12. The method according to claim 3, wherein the self-assembled monomolecular layer completely covers an external surface of the at least one metal nanowire.

13. The method according to claim 3, wherein the at least one nanowire comprises a metal chosen from silver, gold, copper, platinum, palladium, nickel, cobalt, rhodium, iridium, ruthenium, and iron.

14. The method according to claim 3, wherein in formula I, R.sup.1 is H, Z is S, and R.sup.2 is a saturated C.sub.3 to C.sub.8 alkyl chain or a substituted or unsubstituted C.sub.4 to C.sub.10 aromatic group.

15. The method according to claim 3, wherein formula I is chosen from 1-propanethiol, 1-decanethiol, 1-octadecanethiol, benzenethiol, 4-methoxybenzenethiol, or 4-trifluoromethylbenzenethiol.

16. The method according to claim 3, wherein the depositing further comprises deposition of at least one thermochromic compound chosen from crystal violet lactone, vanadium dioxide, and mixtures thereof.

17. The method according to claim 3, wherein the plastic material is chosen from polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), and a silicone.

18. The method according to claim 3, wherein the substrate has a thickness of from 2 m to 500 m.

19. The method according to claim 3, further comprising the deposition of a layer for encapsulation of the substrate, said encapsulation comprising a polymer material chosen from an ethylene/vinyl acetate (EVA) polymer, a vinyl butyral polymer (PVB), and a urethane polymer.

20. The method according to claim 16, further comprising the deposition of an insulation layer on the surface of the substrate on which the deposition of the at least one metal nanowire and of the thermochromic compound is carried out.

21. The method according to claim 16, wherein the deposition of the at least one metal nanowire is carried out before the deposition of the thermochromic compound.

22. The method according to claim 16, wherein the deposition of the metal nanowire is carried out after the deposition of the thermochromic compound.

23. The method according to claim 3, wherein the deposition of the at least one metal nanowire is carried out by projection under pressure, the use of an inkjet machine or a spin coater, by flexography, by photogravure, or by use of a scraper.

Description

Example 1

(1) Silver nanowires are manufactured according to the following process:

(2) 1.766 g of PVP (polyvinylpyrrolidone) are added to 2.6 mg of NaCl (sodium chloride) in 40 ml of EG (ethylene glycol). The mixture is stirred at 600 revolutions per minute (rpm) at 120 C. until the PVP+NaCl has completely dissolved (approximately 4-5 minutes). This mixture is added dropwise, using a dropping funnel, to a solution of 40 ml of EG in which 0.68 g of AgNO.sub.3 (silver nitrate) is dissolved. The oil bath is heated to 160 C. and stirring is allowed to take place at 700 rpm for 80 minutes. Three washing operations are carried out with methanol, centrifuging being carried out at 2000 rpm for 20 min, then the nanowires are precipitated with acetone and, finally, redispersed in water or methanol.

(3) The electrodes are produced on PEN (polyethylene naphthalate) with a thickness of 125 m by vaporization of the solution using an Aztek A4709 airbrush or by spin coating.

(4) The substrates thus formed have a sheet resistance of 35 ohms/square at 91% transmission (at 550 nm).

(5) A localized deposition of thermochromic ink based on p-methylphenol and on hexadecanol and on crystal violet lactone is carried out on the transparent electrode.

(6) Heating is obtained by application of a voltage of 6 V to the electrode.

(7) At the temperature of approximately 45 C., the zone defined by the thermochromic compound which was dark blue became transparent.

(8) After cooling, the blue color reappeared. The cycle is thus repeated 10 times without modifying the reactivity of the thermochromic compound.

Example 2

(9) Gold nanowires are manufactured according to the following process:

(10) 400 l of HAuCl.sub.4 (30% in HCl) are added to 2 ml of hexane and 10 ml of OA (oleylamine) at 80 C. Vigorous stirring is allowed to take place for 5 min and the mixture is left at this temperature, the stirring being switched off, for 5 h. The reaction mixture becomes very red. A precipitate (deep black product) is obtained by adding ethanol. After centrifuging at 3400 rev.Math.min.sup.1 and washing with ethanol for 10 min, the nanowires are dispersed in hexane.

(11) Electrodes are produced on PEN (polyethylene naphthalate) with a thickness of 10 m by vaporization of the solution using an Aztek A4709 airbrush, the substrates being heated at 60 C.

(12) The substrates thus formed have a sheet resistance of 55 ohms/square at 87% transmission (at 550 nm).

(13) A localized deposition of thermochromic ink based on p-methylphenol and on hexadecanol and on crystal violet lactone is carried out on the transparent electrode.

(14) Heating is obtained by application of a voltage of 6 V to the electrode.

(15) At the temperature of approximately 45 C., the zone defined by the thermochrome which was dark blue becomes transparent.

(16) After cooling, the blue color reappears. The cycle is carried out 10 times without modifying the reactivity of the thermochromic compound.

Example 3

(17) Copper nanowires are manufactured according to the process described in the publication B. J. Wiley et al., Advanced Materials, 2011, 23, pp. 4798-4803.

(18) Electrodes are produced on PEN (polyethylene naphthalate) with a thickness of 10 m by vaporization of the solution using an Aztek A4709 airbrush, the substrate being heated at 65 C.

(19) The substrates thus formed have a sheet resistance of 52 ohms/square at 91% transmission (at 550 nm).

(20) A localized deposition of Chameleon Reversible Thermochromic Inks Red 47 C. ink, sold by B&H Colour Change, is carried out on the transparent electrode by vaporization.

(21) Heating is obtained by application of a voltage of 6 V to the electrode.

(22) At the temperature of approximately 47 C., the zone defined by the thermochromic compound which was red becomes transparent.

(23) After cooling, the red color reappears. The cycle is thus repeated 10 times without modifying the reactivity of the thermochromic compound.