Polymer composition and polymer light emitting device

A polymer composition comprising 1 to 99 wt % of the following copolymer (A) and 99 to 1 wt % of the following copolymer (B):

• Copolymer (A):
• a copolymer showing fluorescence in the solid state and having a polystyrene-reduced number average molecular weight of 103 to 108, and containing a repeating unit (a) and a repeating unit (b), and said copolymer has a relation of 100>XaA>5, provided that XaA (%) is a percentage of the mol number of the repeating unit (a) based on the sum of the mol numbers of the repeating units (a) and (b), and
• Copolymer (B):
• a copolymer showing fluorescence in the solid state and having a polystyrene-reduced number average molecular weight of 103 to 108, and containing (a) a repeating unit and (b) a repeating unit, and said copolymer satisfies a relation of XaB≦XaA−5, provided that XaB (%) is a percentage of the mol number of the repeating unit (a) based on the sum of the mol numbers of the repeating units (a) and (b);
• wherein the repeating unit (b) is a repeating unit represented by the following formula (2):
• wherein, X represents —CR3R4—, —O—, —S—, —Se— or —SiR5R6—, p and q represent each independently an integer of 0 to 3, R1 and R2 represent each independently an alkyl group, aryl group or mono-valent heterocyclic group;
• two or more of R1 and R2 may be connected to form a cyclic structure;
• R3, R4, R5 and R6 represent each independently an alkyl group, alkoxy group, alkylthio group, alkylsilyl group, alkylamino group, aryl group, aryloxy group, arylsilyl group, arylamino group, arylalkyl group, arylalkoxy group, arylalkylsilyl group, arylalkylamino group, mono-valent heterocyclic group or cyano group;
• when there are a plurality of R1 and R2, respectively, they may be the same or different;
• and further, when R1, R2, R3, R4, R5 and R6 are groups having an alkyl, the alkyl may be interrupted by a group containing a hetero atom, and
• wherein when X represents —CR3R4—, two or more of R1 and R2 are connected to form a cyclic structure.