Efficient blue fluorescent electroluminescence based on a tert-butylated 9,9′-bianthracene derivative with a twisted intramolecular charge-transfer excited state

An orthogonally twisting tert-butylated 9,9'-bianthracene derivative, namely 10,10'-bis(4-tert-butyl-phenyl)-9,9'-bianthracene (BAn-(4)-tBu), possessing high thermal stability and high luminescence efficiency was synthesized. The BAn-(4)-tBu emitter with a twisted intramolecular charge transfer state characteristics, originating from its twisting 9,9'-bianthracene moiety, enhanced the occurrence of singlet excitons in the fluorescent emitter. The BAn-(4)-tBu device doped with sky blue fluorescent material 4,4-bis[4-(di-p-tolylamino)styryl]biphenyl displayed a maximum singlet generation fraction of >25%, maximum current and external quantum efficiencies of 6.00 cd A(-1) and 3.22%, respectively. Remarkably, a low efficiency roll-off was observed. These results demonstrated that BAn-(4)-tBu as a host material is advantageous for fabrication of highly efficient blue fluorescent organic light-emitting devices. (C) 2016 Elsevier B.V. All rights reserved.