Optical filter and imaging device

1. An optical filter, comprising:

an absorption layer containing a near-infrared absorbing dye with an absorption characteristic which is measured by dissolving the near-infrared absorbing dye in dichloromethane and satisfies (i-1) to (i-3):

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

(i-2) a maximum absorption coefficient ε A of light with a wavelength of 430 to 550 nm and a maximum absorption coefficient ε B of light with a wavelength of 670 to 730 nm satisfy the following expression:

ε B /ε A ≥65, and

(i-3) in a spectral transmittance curve, the maximum absorption wavelength λ max and a wavelength λ 80 satisfy (λ max −λ 80 )≤65, where λ 80 is an absorption wavelength with which the transmittance becomes 80% on a shorter wavelength side than the maximum absorption wavelength with the transmittance at the maximum absorption wavelength λ max set to 10%,

wherein

the near-infrared absorbing dye is a squarylium-based dye represented by formula (AI) or formula (AII):

where

X is independently a bivalent organic group represented by formula (1) or formula (2), in which one or more hydrogen atoms are optionally substituted with a halogen atom or an alkyl group or alkoxy group having 1 to 12 carbon atoms:

—(CH 2 ) n1 —  (1)

in the formula (1), n1 is 2 or 3;

—(CH 2 ) n2 —O—(CH 2 ) n3 —  (2)

in the formula (2), n2 and n3 are independently an integer of 0 to 2, and n2+n3 is 1 or 2;

R 1 independently represents a saturated or unsaturated hydrocarbon group having 1 to 12 carbon atoms which optionally have a branch and optionally contain a saturated ring structure, a saturated cyclic hydrocarbon group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alaryl group having 7 to 13 carbon atoms;

R 2 independently represents a hydrocarbon group having 1 to 25 carbon atoms in which one or more hydrogen atoms are optionally substituted with a halogen atom, a hydroxy group, a carboxy group, a sulfo group, or a cyano group and which optionally contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms;

R 3 , R 4 , R 5 , and R 6 independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms; and

n is 2 or 3.

2. The optical filter according to claim 1 , wherein

the absorption layer is provided on a transparent substrate.

3. The optical filter according to claim 2 , wherein

the transparent substrate comprises a glass.

4. The optical filter according to claim 3 , wherein

the glass is a near-infrared absorbing glass.

5. The optical filter according to claim 2 , wherein

the transparent substrate comprises a resin.

6. The optical filter according to claim 1 , wherein

X in the formula (AI) and the formula (AII) is a bivalent organic group represented by formula (3):

—CR 7 2 —(CR 8 2 ) n4 —  (3)

where the formula (3) represents a bivalent group in which the left side is bonded to a benzene ring and the right side is bonded to N,

n4 is 1 or 2,

R 7 is independently an alkyl group or alkoxy group having 1 to 12 carbon atoms which optionally have a branch, and

R 8 is independently a hydrogen atom or an alkyl group or alkoxy group having 1 to 12 carbon atoms which optionally have a branch.

7. The optical filter according to claim 6 , wherein

in the formula (3), R 7 is independently an alkyl group or alkoxy group having 1 to 6 carbon atoms which optionally have a branch, and R 8 is independently a hydrogen atom or an alkyl group or alkoxy group having 1 to 6 carbon atoms which optionally have a branch.

8. The optical filter according to claim 1 , wherein the absorption layer further contains an ultraviolet absorbing dye satisfying (ii-11:

(ii-1) a maximum absorption wavelength occurs in a range of 360 to 415 nm in an absorption spectrum of a wavelength of 350 to 800 nm measured by dissolving the ultraviolet absorbing dye in dichloromethane.

9. The optical filter according to claim 8 , wherein

the ultraviolet absorbing dye is a compound represented by formula (M):

where Y represents an oxygen atom or a methylene group substituted with Q 6 and Q 7 which independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms;

Q 1 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which optionally have a substituent;

Q 2 , Q 3 , Q 4 and Q 5 each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms; and

Z represents a bivalent group represented by one of formula (Z1) to formula (Z5):

where Q 8 and Q 9 are both independently a monovalent hydrocarbon group having 1 to 12 carbon atoms which optionally have a substituent, and Q 10 to Q 19 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which optionally have a substituent.

10. The optical filter according to claim 8 , wherein

the absorption layer comprises a near-infrared absorbing layer containing the near-infrared absorbing dye and an ultraviolet absorbing layer containing the ultraviolet absorbing dye.

11. The optical filter according to claim 1 having a spectral characteristic satisfying (iv-1):

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

12. The optical filter according to claim 11 , wherein

the spectral characteristic further satisfies one of (iv-2) to (iv-6):

(iv-2) an average transmittance of light with a wavelength of 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 with a wavelength of 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 with a wavelength of 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 an absolute value of a difference between a transmittance of light with a wavelength of 385 to 430 nm in a spectral transmittance curve at an incident angle of 0° and a transmittance of light with a wavelength of 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 an absolute value of a difference between a transmittance of light with a wavelength of 600 to 700 nm in a spectral transmittance curve at an incident angle of 0° and a transmittance of light with a wavelength of 600 to 700 nm in a spectral transmittance curve at an incident angle of 30° is 7%/nm or less.

13. The optical filter according to claim 1 , wherein

in the formula (AI) and the formula (AII), X is one of bivalent organic groups represented by formula (11-1) to formula (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 —C(CH 3 ) 2 —  (11-4)

—C(CH 3 ) 2 —C(CH 3 )(C 2 H 5 )—  (11-5)

—C(CH 3 ) 2 —C(CH 3 )(CH(CH 3 ) 2 )—  (11-6)

—C(CH 3 ) 2 —CH 2 —CH 2 —  (12-1)

—C(CH 3 ) 2 —CH 2 —CH(CH 3 )—  (12-2)

—C(CH 3 ) 2 —CH(CH 3 )—CH 2 —  (12-3)

where groups represented by the formula (11-i) to the formula (12-3) are bonded to a benzene ring at the left side and are bonded to N at the right side respectively.

14. The optical filter according to claim 1 , wherein

in the formula (AI) and the formula (AII), R 1 is independently a group represented by formula (4-1) or formula (4-2):

where R 11 , R 12 , R 13 , R 14 , and R 15 independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

15. The optical filter according to claim 1 , wherein

in the formula (AI), R 2 is independently an alkyl group or alkoxy group having 1 to 12 carbon atoms which optionally have a branch, or a hydrocarbon group having 6 to 16 carbon atoms which contains an unsaturated ring structure.

16. 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.

17. The optical filter according to claim 1 , further comprising:

a selected wavelength blocking layer satisfying (iii-1) and (iii-2) provided on at least one main surface of the absorption layer:

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

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

18. The optical filter according to claim 1 , wherein

an average transmittance of light with a wavelength of 430 to 480 nm is 87% or more in a spectral transmittance curve at an incident angle of 0°.

19. The optical filter according to claim 1 , wherein

the absorbing layer functions as a resin substrate.

20. An imaging device, comprising

a solid-state image sensing device,

an imaging lens, and

the optical filter according to claim 1 .