Organic semiconductor element, strain sensor, vibration sensor, and manufacturing method for organic semiconductor element

A method for producing an organic semiconductor element, comprising:

• forming an organic semiconductor film formed from single crystal of an organic semiconductor on a substrate;
• and
• forming a dopant film for supplying carriers to a surface of the organic semiconductor film, wherein, in forming a dopant film, a treatment liquid, which is obtained by dissolving, in an ionic liquid including a first ion which serves as a dopant in the form of a cation or an anion or an organic solvent having dissolved therein a salt including a first ion which serves as a dopant in the form of a cation or an anion, a second ion which has the same polarity as that of the first ion and which oxidizes or reduces the organic semiconductor, is allowed to be in contact with the surface of the organic semiconductor film to form an intermediate of the second ion and the organic semiconductor by a redox reaction, and to replace the second ion in the intermediate with the first ion.