Efficient helical columnar emitters of chiral homoleptic Pt(ii) metallomesogens for circularly polarized electroluminescence

Chem Sci. 2024 Oct 10. doi: 10.1039/d4sc05781c. Online ahead of print.

Abstract

Chiral organometallic Pt(ii) complexes have been demonstrated to be excellent circularly polarized luminescence (CPL) materials due to their rich phosphorescence and strong self-assembly characteristics. However, it remains a formidable task to simultaneously achieve high luminance (L) and electroluminescence dissymmetry factor (g EL) values for circularly polarized electroluminescence (CP-EL) devices of Pt(ii) complex-based emitters. In this study, we carry out a straightforward and efficient protocol to construct highly CPL-active helical columnar () emitters by using chiral homoleptic triazolatoplatinum(ii) metallomesogens (R/S-HPt). The peripheral flexible groups can not only improve solubility but also favor the induction of chirality and liquid crystal behavior. The resultant complexes R/S-HPt can self-assemble into the mesophase over a broad temperature range (6-358 °C) and exhibit excellent phosphorescence (Φ: up to 86%), resulting in intense CPL signals after thermal annealing (λ em = 615 nm and |g em| = 0.051). Using emitting layers (EML) based on R/S-HPt in solution-processed CP-EL devices, L max and |g EL| of CP-EL can reach up to 11 379 cd m-2 and 0.014, respectively. With comprehensive consideration of L max and g EL, this investigation shows the excellent performances among Pt(ii) complex-based CP-EL devices.