Compounds having a structure of Formula I, where G1 has the formula having the structure are described. In the structure of Formula I: Z1 to Z24 are each independently selected from group consisting of carbon and nitrogen; p is an integer from 1 to 10; adjacent carbazole groups G11, G12, and G13 are each bonded together either by a 9N-2C bond or a 9N-3C bond; G1 can include at least one 9N-2C intercarbazole bond and at least one 9N-3C intercarbazole bond; L and G2 are each independently selected from the group consisting of alkyl, aryl, or heteroaryl, which may be further substituted; m and n are both integers; and m+n ranges from 1 to the maximum number of possible substituents on L. Formulations and devices, such as an OLEDs, that include the compound of Formula I are also described.