To provide a composition, obtaining luminescence derived from a low molecular phosphor material almost selectively from the light-emitting element in the case of using the same for the preparation of the light-emitting element.

This composition contains a polymer including a recurring unit expressed by formula (1) [wherein, Ar is independently an aryl which may have a substituent or a monovalent heterocyclic ring which may have a substituent; R1is independently a substituent; and (m) is independently 0 to 3 integer] and a low molecular phosphor material. The thin film by using the same, the organic transistor having the thin film, and a polymer light-emitting element having electrodes consisting of an anode and a cathode and an organic layer containing the composition are also provided.

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