Photoelectric conversion element including transition metal dichalcogenide thin film and light-receiving element including the photoelectric conversion element

A photoelectric conversion element comprising:

• a base material;
• and a thin film formed on the base material and composed of a transition metal dichalcogenide, the photoelectric conversion element acting only in a wavelength range between 700 nm and 1600 nm,
• wherein the transition metal dichalcogenide is a chalcogenide of Pt or Pd, and
• a surface of the thin film composed of the transition metal dichalcogenide is modified with nanorod particles selected from the group consisting of (a) Au nanorod particles composed of Au and having an average aspect ratio of 3.0 or more and 12.0 or less and (b) Ag nanorod particles composed of Ag and having an average aspect ratio of 3.0 or more and 13.0 or less, and
• in an observation of the surface of the thin film composed of the transition metal dichalcogenide and modified with the nanorod particles, an area ratio of the nanorod particles in an observation field region is 0.1% or more and 1% or less.