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

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.