Derivatives of 9‐phenyl‐9H‐carbazole were synthesized as efficient emitters exhibiting both thermally activated delayed fluorescence and aggregation‐induced emission enhancement. Effects of methoxy and tert‐butyl substituents at the different positions of carbazolyl groups on the properties of the emitters were studied. Depending on the substitutions, photoluminescence quantum yields (PLQY) of non‐doped solid films of the compounds ranged from 17 % to 53 % which were much higher than those observed for the solutions in low‐polarity solvent toluene. Compounds substituted at C‐3 and C‐6 positions of carbazole moiety by methoxy‐ and tert‐butyl‐ groups showed the highest solid‐state PLQY. Ionization potentials of the studied derivatives in solid‐state were found to be in the short range of 5.75–5.89 eV. Well‐balanced hole and electron mobilities were detected for tert‐butyl‐substituted compound. They exceeded 10−4 cm2 (V×s)−1 at electric fields higher than 3×105 V cm−1. Two compounds with the highest solid‐state PLQYs showed higher efficiencies in non‐doped organic light‐emitting diodes than in the doped devices. Maximum external quantum efficiency of 7.2 % and brightness of 15000 cd m−2 were observed for the best device.