An efficient solution-processable non-doped hybridized local and charge-transfer (HLCT) emitter for a simplified organic light-emitting diode

Here, a new solution-processable hybridized local and charge-transfer (HLCT) fluorescent molecule, CPBzFC , is designed and synthesized as an efficient emitter for low-cost and simple-structured electroluminescent devices. CPBzFC contains 7-(4-(carbazol- N -yl)phenyl)benzothiadiazole as an HLCT fragment directly linked to a hole-transporting and highly soluble 7-(3,6-di- tert -butylcarbazol- N -yl)-9,9′-bis(8-(3,6-di- tert -butylcarbazol- N -yl)octyl)fluorene part. The photophysical results and theoretical calculations unveil an HLCT excited-state character with a strong yellowish-green fluorescence emission (a solid-state photoluminescence quantum yield of 82%), decent hole-transporting mobility, good film morphology, and thermal and electrochemical stabilities. CPBzFC is successfully utilized as a solution-processed non-doped emitter in simple structured OLEDs. This device achieves excellent electroluminescence (EL) performance with an ultra-high brightness of 30 800 cd m −2 , a maximum external quantum efficiency (EQE max )of 6.74%, a maximum current efficiency (CE max ) of 14.38 cd A −1 , and a high exciton utilization efficiency (EUE) of 41%. A solution-processable HLCT fluorescent molecule realizes a highly efficient non-doped OLED with a high brightness of 30 800 cd m −2 , a maximum external quantum efficiency (EQE max ) of 6.74% and a maximum current efficiency (CE max ) of 14.38 cd A −1 .