An orthogonally twisting tert-butylated 9,9′-bianthracene derivative, namely 10,10′-bis(4-tert-butylphenyl)-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 6.00cdA−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.