Carbazole-pyrene derivatives for undoped organic light-emitting devices

► BPyC and TPyC have similar chemical structures and PL properties. ► BPyC-based devices show blue emission while TPyC-based devices exhibit blue and yellow hues. ► It is attributed to exciplex formation at TPyC/TPBI interface. ► High EQE of 3.11% is achieved in the TPyC-based devices. ► Efficiency of exciplex emission is found to be dependent on chemical structure and ΦPL.