Near-infrared electroluminescence beyond 940 nm in Pt(N^C^N)X complexes: influencing aggregation with the ancillary ligand X

Abstract

The ancillary ligand X strongly influences the aggregates formed by complexes of the type Pt(N^C^N)X. X = I leads to a 4× increase in film PLQY and OLED EQE vs. X = Cl, while X = SCN yields very long wavelength electroluminescence, λmaxEL = 944 nm.

Luminescence and Palladium: The Odd Couple

“… Schematic representation of the old and new concepts presented to recover and amplify the luminescence of transition metal complexes. Adapted from references [ 27 , 28 ] (complexes of the first row metals), [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ] (orthometallation), [ 36 , 37 ] (RIM), [ 38 , 39 , 40 ] (AIE) and [ 41 , 42 , 43 , 44 ] (TADF). …”

“…A well established methodology to achieve this task is the use of strong-field ligands mainly containing C and N as donor atoms, although P and S are also used in lower extent ( Figure 1 ). Cyclometallated ligands are by far the type of ligands most extensively used for this purpose due to several reasons [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. The main one is that they promote very large splittings of the crystal field, raising non-emissive d-d MC states and further decreasing non-radiative relaxation.…”

Near-infrared metal agents assisting precision medicine: from strategic design to bioimaging and therapeutic applications

“…In 2022, Gareth Williams et al designed a novel series of Pt( ii ) complexes based on the Pt(N–C–N)X skeleton. 123 It has been demonstrated that SCN- or I-containing complexes can modulate the formation of the aggregates more than Cl-containing complexes. I-containing complexes had been found to restrict the formation of aggregates in dimers.…”

Incorporation of a Fluorine Atom in a Bridging Ligand of Half-Lantern PtII2 Complexes Provides up to 10-Fold Enhancement of Electroluminescence Brightness

“…Phosphorescent platinum­(II) complexes are a subject of rapidly growing interest in view of their potential applications in bioimaging, − photocatalysis, − and also their usage as components of organic light emitting diodes (OLEDs). − One of the most explored types of phosphorescent Pt II systems include cyclometalated species featuring aromatic C ∧ N or C ∧ C scaffolds; these complexes conventionally display excellent luminescent properties. ,,− …”