There is disclosed a compound having Formula I In Formula I: Ar1 through Ar4 are the same or different and are aryl groups; L is a spiro group, an adamantyl group, bicyclic cyclohexyl, deuterated analogs thereof, or substituted derivatives thereof; R1 is the same or different at each occurrence and is D, F, alkyl, aryl, alkoxy, silyl, or a crosslinkable group, where adjacent R1 groups can be joined together to form an aromatic ring; R2 is the same or different at each occurrence and is H, D, or halogen; a is the same or different at each occurrence and is an integer from 0-4; and n is an integer greater than 0.