There is provided a compound having Formula I In Formula I: BCz is a substituted or unsubstituted benzocarbazole unit; L1 and L2 are the same or different and are H, D, halogen, aryl, arylamino, crosslinkable groups, deuterated aryl, deuterated arylamino, or deuterated crosslinkable groups; Q1 and Q2 are the same or different and are a single bond, alkyl, aryl, heteroaryl, diarylamino, triarylamino, deuterated alkyl, deuterated aryl, deuterated heteroaryl, deuterated diarylamino, or deuterated triarylamino; and n is an integer greater than 0, with the proviso that when n=1, L1 and L2 are Cl, Br, crosslinkable groups or deuterated crosslinkable groups.