Crosslinkable hole transport materials

A copolymer having Formula IV

• [[A]x[M1]y[M2]z[E]w] (IV)
• wherein:
• A is a monomeric unit having Formula A-2a
• wherein:
• Ar2 is the same or different at each occurrence and is an aryl or deuterated aryl group;
• R5 through R9 are independently the same or different at each occurrence and are selected from the group consisting of D, F, CN, alkyl, fluoroalkyl, aryl, heteroaryl, amino, silyl, germyl, alkoxy, aryloxy, fluoroalkoxy, siloxane, siloxy, deuterated alkyl, deuterated partially-fluorinated alkyl, deuterated aryl, deuterated heteroaryl, deuterated amino, deuterated silyl, deuterated germyl, deuterated alkoxy, deuterated aryloxy, deuterated fluoroalkoxy, deuterated siloxane, deuterated siloxy, and crosslinking groups, wherein adjacent R5 or R9 groups can be joined together to form a fused 5- or 6-membered aromatic ring;
• a1 is the same or different at each occurrence and is an integer from 0 to 4;
• f is the same or different at each occurrence and is 0 to the maximum number of bonding positions available;
• g is an integer from 0 to 3;
• h and h1 are the same or different and are 1 or 2;
• M1 is a monomeric unit having at least three points of attachment in the copolymer;
• M2 is an aromatic monomeric unit having two points of attachment or a deuterated analog thereof;
• E is a monomeric unit having Formula III-a
• wherein:
• L1 is selected from the group consisting of alkyl, aryl, substituted derivatives thereof, deuterated analogs thereof, and combinations thereof;
• R1 and R2 are the same or different and are H or D;
• R3 is the same or different at each occurrence and is selected from the group consisting of D, CN, halogen, alkyl, alkoxy, silyl, germyl, deuterated alkyl, deuterated alkoxy, deuterated silyl, and deuterated germyl;
• R4a is H or D;
• a is an integer from 0-4;
• x, y, z and w are the same or different and are mole fractions, where at least x and w are non-zero;
• and
• * indicates a point of attachment.