Efficient violet non-doped organic light-emitting device based on a pyrene derivative with novel molecular structure

Abstract

A novel pyrene derivative 1,6-bis[2-(3,5-diphenylphenyl)phenyl]pyrene (DPPP) was successfully designed and synthesized. X-ray analysis shows the pyrene core in this compound is fully protected by the introduced 3,5-diphenylphenyl groups, resulting no π–π stacking between pyrene units, and the dihedral angle between pyrene ring and adjacent benzene ring is as large as 80.1°. This structure character leads to DPPP achieving a violet emission both in solution and as a thin solid film. Furthermore, DPPP exhibits high thermal properties due to its non-coplanar structure and large molecular size. The non-doped electroluminescence device employing DPPP as emitting layer shows a stable and efficient violet emission with a maximum external quantum efficiency of 2.2% and a CIE coordinate of (0.16, 0.04), which is remarkable in reported violet devices.