Remote Modification of Bidentate Phosphane Ligands Controlling the Photonic Properties in Their Complexes: Enhanced Performance of [Cu(RN‐xantphos)(N^{^}N)][PF₆] in Light‐Emitting Electrochemical Cells

Abstract

A series of copper(I) complexes of the type [Cu(HN‐xantphos)(N^N)][PF6] and [Cu(BnN‐xantphos)(N^N)][PF6], in which N^N = bpy, Mebpy, and Me2bpy, HN‐xantphos = 4,6‐bis(diphenylphosphanyl)‐10H‐phenoxazine and BnN‐xantphos = 10‐benzyl‐4,6‐bis(diphenylphosphanyl)‐10H‐phenoxazine is described. The single crystal structures of [Cu(HN‐xantphos)(Mebpy)][PF6] and [Cu(BnN‐xantphos)(Me2bpy)][PF6] confirm the presence of N^N and P^P chelating ligands with the copper(I) atoms in distorted coordination environments. Solution electrochemical and photophysical properties of the BnN‐xantphos‐containing compounds (for which the highest‐occupied molecular orbital is located on the phenoxazine moiety) are reported. The first oxidation of [Cu(BnN‐xantphos)(N^N)][PF6] occurs on the BnN‐xantphos ligand. Time‐dependent density functional theory (TD‐DFT) calculations have been used to analyze the solution absorption spectra of the [Cu(BnN‐xantphos)(N^N)][PF6] compounds. In the solid‐state, the compounds show photoluminescence in the range 518–555 nm for [Cu(HN‐xantphos)(N^N)][PF6] and 520–575 nm for [Cu(BnN‐xantphos)(N^N)][PF6] with a blue‐shift on going from bpy to Mebpy to Me2bpy. [Cu(BnN‐xantphos)(Me2bpy)][PF6] exhibits a solid‐state photoluminescence quantum yield of 55% with an excited state lifetime of 17.4 µs. Bright light‐emitting electrochemical cells are obtained using this complex, and it is shown that the electroluminescence quantum yield can be enhanced by using less conducting hole injection layers.

The shiny side of copper: bringing copper(i) light-emitting electrochemical cells closer to application

“…11 Comparison of device properties (maximum luminance and device lifetime) for the complexes described in this work (round coloured dots), compared to devices with previously tested complexes prepared in our group (black squares). 15,[17][18][19]21,24,25 Top: average current density 50 A m À2 ; bottom: average current density 100 A m À2 .…”

“…[11][12][13] The colourtuning of iTMC-based LECs is well-established in the case of iridium complexes, although the use of this element makes again the sustainability questionable. We [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] and others [29][30][31][32][33][34][35][36][37][38] have investigated copper(I) complexes of the type [Cu(P^P)(N^N)] + (P^P ¼ chelating diphosphane, N^N ¼ diimine or 1,10-phenanthroline) as alternative electroluminescent materials for LECs. These complexes are of particular interest as they exhibit the phenomenon of thermally activated delayed uorescence (TADF), in which the rst excited singlet (S 1 ) and triplet (T 1 ) states are strongly coupled, allowing intersystem crossing between the two levels without the need for a heavy metal.…”

TADF: Enabling luminescent copper(i) coordination compounds for light-emitting electrochemical cells

“…Values of Lum max also depended on the PEDOT : PSS composition, reaching 203 or 355 cd m -2 . Overall, the LECs with [Cu(BnNxantphos)(6,6'-Me 2 bpy)][PF 6 ] showed good lifetimes, intense EL and EQE >1%, making them some of the best performing devices with [Cu(P^P)(N^N)] + emitters 127.…”

The Role of Percent Volume Buried in the Characterization of Copper(I) Complexes for Lighting Purposes

“…Similarly, PLQY values obtained under air were chosen over values obtained under an Ar atmosphere where such differentiations were made [31]. A total of 100 compounds were found and their %V bur was calculated for the (NN), (PP) and (NN)(PP) units which are referred to as %V bur (NN), %V bur (PP) and %V bur (NN + PP) (Table S1, supporting information) [17][18][19][20][21][23][24][25][26][27][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. All compounds contain bidentate diimine and bisphosphane ligands with one exception containing a bidentate diimine and two monodentate triphenylphosphano ligands (CCDC: 1558486) [45].…”