High-performance blue electroluminescence devices based on distyrylbenzene derivatives

Amorphous molecular, distyrylbenzene derivative $2,5,2^{\prime },5^{\prime },2^{″},5^{″}$ -hexastyryl-$[1,1^{\prime };4^{\prime },1^{″}]$ terphenyl (HSTP) is sandwiched between NPB and $\mathrm{Al}{\mathrm{q}}_3$ as blue light-emitting material in typical multilayer organic light-emitting devices, where NPB and $\mathrm{Al}{\mathrm{q}}_3$ are 1,4-bis(1-naphylphenylamino)biphenyl and tris(8-hydroxyquinoline)aluminum, respectively. Formation of exciplex at the interface of NPB and HSTP layer is verified by study on photoluminescence and electroluminescence (EL) spectra. The performance of EL can be greatly improved by optimizations of devices; a pure blue device with Internationale de l’Eclairage coordination (0.16, 0.13), maximum brightness of $15830\mathrm{cd}∕{\mathrm{m}}^2$ , and current efficiency of $4.88\mathrm{cd}∕\mathrm{A}$ is obtained.