Optical filter and imaging device

1. An optical filter, comprising:

an absorption layer comprising a near-infrared absorbing dye and a transparent resin; and

an inorganic or organic material in contact with the absorption layer,

wherein the near-infrared absorbing dye comprises a squarylium-based dye of the following formula (AI):

wherein

each X is independently a bivalent organic group of the following formula (1) or (2), wherein at least one hydrogen atom is optionally substituted with a C 1-12 alkyl or alkoxy group;

(CH 2 ) n1 —  (1),

wherein n1 is 2 or 3;

—(CH 2 ) n2 —O—(CH 2 ) n3 —  (2),

wherein each of n2 and n3 is independently an integer of 0 to 2, and n2+n3 is 1 or 2;

each R 1 independently represents a saturated or unsaturated C 1-12 hydrocarbon group which optionally comprises a saturated ring structure or is optionally branched, a saturated C 3-12 cyclic hydrocarbon group, a C 6-12 aryl group, or a C 7-13 alaryl group;

each R 2 is independently a C 1-25 hydrocarbon group in which at least one hydrogen atom is optionally substituted with a halogen atom, a hydroxyl group, a carboxy group, a sulfo group, or a cyano group and that optionally comprises an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms; and

R 3 and R 4 each independently represent a hydrogen atom, a halogen atom, or a C 1-10 alkyl or alkoxy group.

2. The optical filter according to claim 1 , wherein

X is a bivalent organic group of the following formula (3):

—CR 5 2 -(CR 6 2 ) n4 —  (3)

wherein

the left side is bonded to a benzene ring and the right side is bonded to N,

n4 is 1 or 2,

each R 5 is independently a C 1-12 alkyl or alkoxy group that may be branched, and

each R 6 is independently a hydrogen atom, or a C 1-12 alkyl or alkoxy group that may be branched.

3. The optical filter according to claim 2 , wherein each R 5 is independently a C 1-6 alkyl or alkoxy group that may be branched, and each R 6 is independently a hydrogen atom or a C 1-6 alkyl or alkoxy group that may be branched.

4. The optical filter according to claim 1 , wherein

X is a bivalent organic group having a formula selected from the group consisting of the following formulas (11-1) to (12-3):

—C(CH 3 ) 2 —CH(CH 3 )—  (11-1),

—C(CH 3 ) 2 —CH 2 —  (11-2),

—C(CH 3 ) 2 —CH(C 2 H 5 )—  (11-3),

—C(CH 3 ) 2 —CH 2 —CH 2 —  (12-1),

—C(CH 3 ) 2 —CH 2 —CH(CH 3 )—  (12-2), and

—C(CH 3 ) 2 —CH(CH 3 )—CH 2 —  (12-3),

wherein the left side of each formula is bonded to a benzene ring and the right side of each formula is bonded to N.

5. The optical filter according to claim 1 , wherein

each R 1 is independently a group of the following formula (4-1) or (4-2);

wherein each of R 7 , R 8 , R 9 , R 10 , and R 11 independently represent a hydrogen atom, a halogen atom, or a C 1-4 alkyl group.

6. The optical filter according to claim 1 , wherein

each R 2 is independently a C 1-12 alkyl or alkoxy group that may be branched.

7. The optical filter according to claim 1 , wherein

the squarylium-based dye of the formula (A1) has an absorption characteristic, measured by dissolving in dichloromethane, satisfying the following (i-1) to (i-3):

(i-1) a maximum absorption wavelength λ max is in a wavelength range of from 670 to 730 nm, in an absorption spectrum of a wavelength range of from 400 to 800 nm,

(i-2) the following relational expression is satisfied between a maximum absorption constant ε A of light of a wavelength range of from 430 to 550 nm and a maximum absorption constant ε B of light of a wavelength range of from 670 to 730 nm:

ε B /ε A ≥50, and

(i-3) a difference between a wavelength λ 80 at which a transmittance becomes 80% on a shorter wavelength side than the maximum absorption wavelength with a transmittance at the maximum absorption wavelength λ max set to 10% and the maximum absorption wavelength λ max , is 60 nm or less, in a spectral transmittance curve.

8. The optical filter according to claim 1 , wherein

the near-infrared absorbing dye is dissolved or dispersed in a transparent resin comprising at least one selected from the group consisting of an acrylic resin, an epoxy resin, an ene-thiol resin, a polycarbonate resin, a polyether resin, a polyarylate resin, a polysulfone resin, a polyethersulfone resin, a polyparaphenylene resin, a polyarylene ether phosphine oxide resin, a polyimide resin, a polyamide-imide resin, a polyolefin resin, a cyclic olefin resin, and a polyester resin.

9. The optical filter according to claim 1 , wherein

the absorption layer comprises a silane coupling agent having at least one group selected from the group consisting of a vinyl group, an epoxy group, a styryl group, a methacrylic group, an acrylic group, an amino group, an ureido group, a mercapto group, a sulfide group, and an isocyanate group.

10. The optical filter according to claim 1 , wherein

the absorption layer comprises an ultraviolet absorbing dye satisfying the following (ii-1):

(ii-1) a maximum absorption wavelength is in a wavelength region of from 360 to 415 nm, in an absorption spectrum of a wavelength of from 350 to 800 nm measured by dissolving in dichloromethane.

11. The optical filter according to claim 10 , wherein

the ultraviolet absorbing dye is a compound of the following formula (M):

wherein

Y represents a methylene group or an oxygen atom substituted with Q 6 and Q 7 wherein each of Q 6 and Q 7 independently represents a hydrogen atom, a halogen atom, or a C 1-10 alkyl or alkoxy group;

Q 1 represents a monovalent C 1-12 hydrocarbon group that is optionally substituted;

each of Q 2 to Q 5 independently represents a hydrogen atom, a halogen atom, or a C 1-10 alkyl or alkoxy group; and

Z represents a bivalent group of having a formula selected from the groups consisting of the following formulas (Z1) to (Z5):

wherein each of Q 8 and Q 9 independently represents a monovalent C 1-12 hydrocarbon group that is optionally substituted, and each of Q 10 to Q 19 is independently a hydrogen atom or a monovalent C 1-12 hydrocarbon group that is optionally substituted.

12. The optical filter according to claim 1 , wherein

the absorption layer is in contact with a transparent substrate or a dielectric multilayer film.

13. The optical filter according to claim 12 , wherein the transparent substrate comprises a glass.

14. The optical filter according to claim 13 , wherein the glass is a near-infrared absorbing glass.

15. The optical filter according to claim 1 , further comprising a selected wavelength blocking layer satisfying the following (iii-1) and (iii-2);

(iii-1) a transmittance of light of a wavelength range of from 420 to 695 nm is 90% or more in spectral transmittance curves at incident angles of 0° and 30°, respectively, and

(iii-2) a transmittance of light of a wavelength range of λ b nm to 1100 nm is 1% or less in spectral transmittance curves at incident angles of 0° and 30°, respectively, wherein λ b is a maximum wavelength at which a transmittance of light of a wavelength range of from 650 to 800 nm of the absorption layer becomes 1%.

16. The optical filter according to claim 1 , having a spectral characteristic satisfying the following (iv-1);

(iv-1) an average transmittance of light of a wavelength range of from 430 to 550 nm is 90% or more, and a minimum transmittance of light of a wavelength range of 4 from 30 to 550 nm is 75% or more in a spectral transmittance curve at an incident angle of 0°.

17. The optical filter according to claim 16 , wherein

the spectral characteristic further satisfies at least one of the following (iv-2) to (iv-6);

(iv-2) an average transmittance of light of a wavelength range of from 600 to 700 nm is 25% or more in a spectral transmittance curve at an incident angle of 0°,

(iv-3) an average transmittance of light of a wavelength range of from 350 to 395 nm is 2% or less in a spectral transmittance curve at an incident angle of 0°,

(iv-4) an average transmittance of light of a wavelength range of from 710 to 1100 nm is 2% or less in a spectral transmittance curve at an incident angle of 0°,

(iv-5) an average value of absolute values each being a difference between a transmittance of light of a wavelength range of from 385 to 430 nm in a spectral transmittance curve at an incident angle of 0° and a transmittance of light of a wavelength range of from 385 to 430 nm in a spectral transmittance curve at an incident angle of 30° is 7%/nm or less, and

(iv-6) an average value of absolute values each being a difference between a transmittance of light of a wavelength range of from 600 to 700 nm in a spectral transmittance curve at an incident angle of 0° and a transmittance of light of a wavelength range of from 600 to 700 nm in a spectral transmittance curve at an incident angle of 30° is 7%/inn or less.

18. An imaging device, comprising:

a solid-state image sensing element; and

the optical filter according to claim 1 .