| abstract |
A polymer for use in an optical device comprising a first, optionally substituted, repeat unit of formula n nand a second, optionally substituted, repeat unit of formulan n nwherein each Ar and Ar′ is the same or different and comprises an optionally substituted aryl or heteroaryl group and optionally a third, optionally substituted, repeat unit in a molar ratio of no greater than 5%, the third repeat unit having a formula —Ar—N(Ar)—Ar— and having a single nitrogen atom in its backbone. |