Light-absorbing composition and optical filter

A light-absorbing composition comprising:

• a light absorber formed by a phosphonic acid represented by the following formula (a) and copper ion;
• and
• an alkoxysilane monomer for dispersing the light absorber, wherein
• the light-absorbing composition does not contain a phosphoric acid ester having a polyoxyalkyl group,
• the light-absorbing composition contains the alkoxysilane monomer in such a manner that a normalized transmittance spectrum has a wavelength band in which a spectral transmittance is 70% or more in a wavelength range from 300 nm to 700 nm and a difference between a maximum value and a minimum value among wavelengths in the wavelength band is 100 nm or more, and
• the normalized transmittance spectrum is obtained by normalizing a transmittance spectrum such that a spectral transmittance at a wavelength of 700 nm is 20%, the transmittance spectrum being obtained when light having a wavelength from 300 nm to 1200 nm is perpendicularly incident on a light-absorbing layer that is formed by subjecting a film formed of the light-absorbing composition to a drying treatment and a humidifying treatment:
• where R11 is an alkyl group, an aryl group, a nitroaryl group, a hydroxyaryl group, or a halogenated aryl group in which at least one hydrogen atom in an aryl group is substituted by a halogen atom.