Substituted benzo[4,5]imidazo[1,2-a]phenanthro[9,10-c][1,8]naphthyridines, benzo[4,5]imidazo[1,2-a]phenanthro[9,10-c][1,5]naphthyridines and dibenzo[f,h]benzo[4,5]imidazo[2,1-a]pyrazino[2,3-c]isoquinolines as thermally assisted delayed fluorescent materials

A compound represented by the formula:

• each R1 independently represents hydrogen, deuterium, halogen, hydroxy, thiol, nitro, cyano, isonitrile, alkylsulfinyl, sulfonic acid, carboxy, hydrazino, aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, trialkylsilyl, triarylsilyl, or trialkoxysilyl;
• and
• each R2 independently represents hydrogen, deuterium, halogen, hydroxy, thiol, nitro, cyano, isonitrile, alkylsulfinyl, sulfonic acid, carboxy, hydrazino, aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, trialkylsilyl, triarylsilyl, or trialkoxysilyl;
• wherein the aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, trialkylsilyl, trialkoxysilyl, and triarylsilyl are each optionally and independently substituted with one or more substituents independently selected from the group consisting of deuterium, halogen, hydroxy, thiol, nitro, cyano, isonitrile, alkylsulfinyl, sulfonic acid, carboxy, hydrazino, aryl, cycloalkyl, cycloalkenyl, heterocyclyl, heteroaryl, alkyl, alkenyl, alkynyl, amino, monoalkylamino, dialkylamino, monoarylamino, diarylamino, alkoxy, aryloxy, haloalkyl, aralkyl, alkoxycarbonyl, acylamino, alkoxycarbonylamino, aryloxycarbonylamino, sulfonylamino, sulfamoyl, carbamoyl, alkylthio, ureido, phosphoramide, trialkylsilyl, trialkoxysilyl, and triarylsilyl.