First light-emitting electrochemical cell with [Ag(i)(N^N)(P^P)] type complex

Abstract

A new heteroleptic complex formulated as [Ag(I)(Bipy)(POP)]BF₄ (Bipy = 2,2′-bipyridine; POP = bis[(2-diphenylphosphino)phenyl]ether) was synthesized and characterized by NMR and X-ray crystallography. The complex adopts tetrahedral coordination geometry. DFT calculations showed that upon excitation the structure of the cationic [Ag(Bipy)(POP)]⁺ complex remains practically unaffected and it is expected to exhibit a relatively small non-radiative decay with a large energy difference between the T₁ and S₀ states to almost 3 eV. The electronic spectrum of the complex exhibits absorption bands with a composite MLCT/LL'CT and IL character. A LEC device (ITO/PEDOT:PSS/Ag(I):[BMIM]PF₆/LiF:Ag) was fabricated that showed a wide emission with a turn-on voltage of ca. 4.5 V and maximum brightness of 395 cd m⁻² at 5.5 V.