A thermally activated delayed fluorescence (TADF) compound comprising one structure of donor-acceptor type or donor-acceptor-donor type selected from the group consisting of: wherein: Y is a carbon or a nitrogen atom, X is independently selected from the group consisting of O, S, N and C(CH 3) 2, R is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, aryl and heteroaryl, A is the acceptor moiety A for the donor-acceptor type selected from the group consisting of: cyano group, benzonitrile, phthalonitrile, isophthalonitrile, terephthalonitrile isonicotinonitrile, benzene-1,3,5-tricarbonitrile, diphenyl sulfone, benzophenone, 1,4-dibenzoylbenzene, 1,3-bis(phenylsulfonyl)benzene, 1,4-bis(phenylsulfonyl)benzene, 2,4,6-triphenyl-1,3,5-triazine, pyrimidine, 2-phenylpyrimidine, 2-methylpyrimidine, pyridine-3,5-dicarbonitrile, 4H-124-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, benzo[d]thiazole, benzo[1,2-d:4,5-d']bis(oxazole), benzo[1,2-d:5,4-d']bis(oxazole), quinoxaline, 1H-benzo[d]imidazole, dibenzo[f,h]quinoxaline, anthracene-9,10-dione, 9H-thioxanthene-9-one 10,10-dioxide, 9,9-dimethyl-9H-thioxanthene 10,10-dioxide, 10,10-dimethylanthracen-9 -one, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, 9H-fluorene-2,7-dicarbonitrile, dibenzo[f,h]quinoxaline-2,3-dicarbonitrile, thianthrene 5,5,10,10-tetraoxide, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile, triphenylborane, tris(2,6-dimethylphenyl)borane and trimesitylborane, A is the acceptor moiety A for the donor-acceptor-donor type selected from the group consisting of: benzonitrile, phthalonitrile, isophthalonitrile, terephthalonitrile isonicotinonitrile, benzene-1,3,5-tricarbonitrile, diphenyl sulfone, benzophenone, 1,4-dibenzoylbenzene, 1,3-bis(phenylsulfonyl)benzene, 1,4-bis(phenylsulfonyl)benzene, 2,4,6-triphenyl-1,3,5-triazine, pyrimidine, 2-phenylpyrimidine, 2-methylpyrimidine, pyridine-3,5-dicarbonitrile, 4H-124-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, benzo[d]thiazole, benzo[1,2-d:4,5-d']bis(oxazole), benzo[1,2-d:5,4-d']bis(oxazole), quinoxaline, 1H-benzo[d]imidazole, dibenzo[f,h]quinoxaline, anthracene-9,10-dione, 9H-thioxanthene-9-one 10,10-dioxide, 9,9-dimethyl-9H-thioxanthene 10,10-dioxide, 10,10-dimethylanthracen-9 -one, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, 9H-fluorene-2,7-dicarbonitrile, dibenzo[f,h]quinoxaline-2,3-dicarbonitrile, thianthrene 5,5,10,10-tetraoxide, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile, triphenylborane, tris(2,6-dimethylphenyl)borane and trimesitylborane. Y is a carbon or a nitrogen atom, X is independently selected from the group consisting of O, S, N and C(CH 3) 2, R is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, aryl and heteroaryl, A is the acceptor moiety A for the donor-acceptor type selected from the group consisting of: cyano group, benzonitrile, phthalonitrile, isophthalonitrile, terephthalonitrile isonicotinonitrile, benzene-1,3,5-tricarbonitrile, diphenyl sulfone, benzophenone, 1,4-dibenzoylbenzene, 1,3-bis(phenylsulfonyl)benzene, 1,4-bis(phenylsulfonyl)benzene, 2,4,6-triphenyl-1,3,5-triazine, pyrimidine, 2-phenylpyrimidine, 2-methylpyrimidine, pyridine-3,5-dicarbonitrile, 4H-124-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, benzo[d]thiazole, benzo[1,2-d:4,5-d']bis(oxazole), benzo[1,2-d:5,4-d']bis(oxazole), quinoxaline, 1H-benzo[d]imidazole, dibenzo[f,h]quinoxaline, anthracene-9,10-dione, 9H-thioxanthene-9-one 10,10-dioxide, 9,9-dimethyl-9H-thioxanthene 10,10-dioxide, 10,10-dimethylanthracen-9 -one, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, 9H-fluorene-2,7-dicarbonitrile, dibenzo[f,h]quinoxaline-2,3-dicarbonitrile, thianthrene 5,5,10,10-tetraoxide, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile, triphenylborane, tris(2,6-dimethylphenyl)borane and trimesitylborane, A is the acceptor moiety A for the donor-acceptor-donor type selected from the group consisting of: benzonitrile, phthalonitrile, isophthalonitrile, terephthalonitrile isonicotinonitrile, benzene-1,3,5-tricarbonitrile, diphenyl sulfone, benzophenone, 1,4-dibenzoylbenzene, 1,3-bis(phenylsulfonyl)benzene, 1,4-bis(phenylsulfonyl)benzene, 2,4,6-triphenyl-1,3,5-triazine, pyrimidine, 2-phenylpyrimidine, 2-methylpyrimidine, pyridine-3,5-dicarbonitrile, 4H-124-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, benzo[d]thiazole, benzo[1,2-d:4,5-d']bis(oxazole), benzo[1,2-d:5,4-d']bis(oxazole), quinoxaline, 1H-benzo[d]imidazole, dibenzo[f,h]quinoxaline, anthracene-9,10-dione, 9H-thioxanthene-9-one 10,10-dioxide, 9,9-dimethyl-9H-thioxanthene 10,10-dioxide, 10,10-dimethylanthracen-9 -one, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, 9H-fluorene-2,7-dicarbonitrile, dibenzo[f,h]quinoxaline-2,3-dicarbonitrile, thianthrene 5,5,10,10-tetraoxide, pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile, triphenylborane, tris(2,6-dimethylphenyl)borane and trimesitylborane.