PHOTODETECTOR ELEMENT, SENSOR AND BIOMETRIC AUTHENTICATION DEVICE INCLUDING SAME, COMPOSITION, AND INK

Provided is a photodetector having a small dark current ratio. A photodetector includes a first electrode, a second electrode, and an active layer provided between the first electrode and the second electrode, the active layer contains a p-type semiconductor material and an n-type semiconductor material, the p-type semiconductor material contains a polymer having the highest occupied molecular orbital (HOMO) of −5.45 eV or less, and the n-type semiconductor material contains a non-fullerene compound. It is preferable that the polymer contained in the p-type semiconductor material contains a constitutional unit DU having an electron donating property and a constitutional unit AU having an electron accepting property, and the non-fullerene compound contains a moiety DP having an electron donating property and a moiety AP having an electron accepting property.