A compound having a formula: G 1 -L-G 2, Formula I; wherein G 1 is selected from the group consisting of: wherein G 2 has the structure: and wherein L is selected from the group consisting of: a direct bond, and wherein X is selected from the group consisting of O, S, and Se; wherein each of Z 1, Z 2, Z 3, Z 4, Z 5, Z 6, Z 7, and Z 8 is carbon or nitrogen; wherein the dashed lines represent the bonds between G 1 and L and G 2 and L; wherein each R 2, R 3, and R 4 represent mono, di, tri, tetra substitutions or no substitution; wherein R 1 represents mono, di, tri substitutions or no substitution; wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein the substitution is optionally fused to G 1 or G 2; wherein when R 3 or R 4 is carbazole or substituted carbazole, the carbazole or substituted carbazole is connected to G 2 by N, and wherein R 3, and R 4 are each independently selected from the group consisting of hydrogen, deuterium, phenyl, pyridyl, 9-carbazolyl, and combinations thereof. wherein G 1 is selected from the group consisting of: wherein G 2 has the structure: and wherein L is selected from the group consisting of: a direct bond, and wherein X is selected from the group consisting of O, S, and Se; wherein each of Z 1, Z 2, Z 3, Z 4, Z 5, Z 6, Z 7, and Z 8 is carbon or nitrogen; wherein the dashed lines represent the bonds between G 1 and L and G 2 and L; wherein each R 2, R 3, and R 4 represent mono, di, tri, tetra substitutions or no substitution; wherein R 1 represents mono, di, tri substitutions or no substitution; wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein the substitution is optionally fused to G 1 or G 2; wherein when R 3 or R 4 is carbazole or substituted carbazole, the carbazole or substituted carbazole is connected to G 2 by N, and wherein R 3, and R 4 are each independently selected from the group consisting of hydrogen, deuterium, phenyl, pyridyl, 9-carbazolyl, and combinations thereof. a direct bond, and wherein X is selected from the group consisting of O, S, and Se; wherein each of Z 1, Z 2, Z 3, Z 4, Z 5, Z 6, Z 7, and Z 8 is carbon or nitrogen; wherein the dashed lines represent the bonds between G 1 and L and G 2 and L; wherein each R 2, R 3, and R 4 represent mono, di, tri, tetra substitutions or no substitution; wherein R 1 represents mono, di, tri substitutions or no substitution; wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein the substitution is optionally fused to G 1 or G 2; wherein when R 3 or R 4 is carbazole or substituted carbazole, the carbazole or substituted carbazole is connected to G 2 by N, and wherein R 3, and R 4 are each independently selected from the group consisting of hydrogen, deuterium, phenyl, pyridyl, 9-carbazolyl, and combinations thereof.