New highly efficient phosphorescent manganese halides as green and blue emitters

Three new manganese compounds on 5-(pyridin-2-yl)-3-phenyl-1,2,4-triazole (L) basis (HL)₄[MnBr₄]₂·H₂O (1), (HL)₂[MnCl₄] (2) and [MnL₂Cl₂]·H₂O (3) have been synthesized and characterized in terms of their structure, photoluminescence (PL), and electroluminescence (EL) properties. Compounds 1 and 2 exhibit bright green luminescence (λ_em ≈ 550 nm) with high quantum yields of 75.1 and 71.2%, and 3 emits unusual blue emission at 438 nm with a quantum yield of 43.9%. Analysis of the spectral properties of complexes 1 and 2 indicates that luminescence is determined by the transfer of excitation energy from the triazole cation to the manganese cation. Electroluminescent devices based on complexes 1 and 3 show high brightness values of 3033 and 5230 Cd m^-2, respectively.