Functional versatile bipolar 3,3′-dimethyl-9,9′-bianthracene derivatives as an efficient host and deep-blue emitter

Abstract

A new family of bipolar fluorinated 3,3′-dimethyl-9,9′-bianthracene derivatives (MBAnFs) have been synthesized, characterized and applied as deep-blue emitters and host materials in fluorescent organic light-emitting devices (OLEDs). Fine tuning the emission characteristics could be achieved by varying the position and the number of the F substituents on the two phenyl rings attached to MBAn core. Remarkably, 10,10′-bis(4-fluorophenyl)-3,3′-dimethyl-9,9′-bianthracene (MBAn-(4)-F)-based OLEDs showed an excellent performance. Both non-doped and doped multilayer OLEDs based on MBAn-(4)-F achieved the maximum external quantum efficiency (EQEmax) of 6.11% and 6.65% with Commission Internationale de L'Eclairage (CIE) coordinates of (0.155, 0.058) and (0.153, 0.055), respectively, matching the requirement of European Broadcasting Union standard of CIE (0.15, 0.06) very well. Furthermore, when doping blue-emitting p-bis(p-N,N-diphenyl-aminostyryl)-benzene (DSA-ph) into MBAn-(4)-F as a light-emitting layer (EML), the device achieved an astonishing current efficiency of 23.01 cd A−1 and a record-setting EQE of 11.52% with negligible efficiency roll-off, compared with other DSA-ph-based OLEDs. These results are attributed to the well-controlled bipolar characteristic of the MABn-(4)-F, leading to a better charge balance in the EML. In addition, the combination of the locally emissive component and twisted intramolecular charge-transfer component in one excited state can significantly enhance the singlet generation fraction in OLEDs.