4CzIPN-tBu (CAS number 1630263-99-8), also known as 2,4,5,6-tetrakis(3,6-di-tert-butylcarbazol-9-yl)-1,3-dicyanobenzene, a donor-acceptor type molecule composed of dicyanobenzene and tert-butyl-substituted carbazolyl groups around the benzene ring.
4CzIPN-tBu is slightly red-shifted in absorption while comparing to that of 4CzIPN as the eight tert-butyl groups improve the donor strength of the carbazole units thus altering the donor–acceptor interaction. Also, due to the bulkier peripheral tert-butyl groups increasing steric effects, 4CzIPN-tBu experiences weaker intermolecular interactions in the solid-state.
Remarkably, the electrogenerated chemiluminescence (ECL) efficiency of 4CzIPN-tBu in dichloromethane reached almost 40% and stable electrogenerated chemiluminescence was observed from 4CzIPN-tBu due to the fact that polymerization is inhibited by the steric hindrance of the bulky tert-butyl groups at 3,6-postion of the carbazoles.
Solution-processed hyperfluorescent devices with an external quantum efficiency (EQE) of 15.3% using cibalackrot as the fluorescent emitter and 4CzIPN-tBu as the TADF assistant host in CBP. These sterically hindered tert-butyl groups effectively reduced losses caused by triplet diffusion between the TADF assistant host and the fluorescent emitter by spatially separating adjacent molecules and making a concurrent frontier molecular orbital (FMO) less likely [1].