Phosphorescent Cationic Au₄Ag₂ Alkynyl Cluster Complexes for Efficient Solution‐Processed Organic Light‐Emitting Diodes

Abstract

Cationic Au4Ag2 heterohexanuclear aromatic acetylides cluster complexes supported by bis(2‐diphenylphosphinoethyl)phenylphosphine (dpep) are prepared. The Au4Ag2 cluster structure originating from the combination of one anionic [Au(C≡CR)2]− with one cationic [Au3Ag2(dpep)2(C≡CR)2]3+ through the formation of Ag−acetylide η2‐bonds is highly stabilized by Au–Ag and Au–Au contacts. The Au4Ag2 alkynyl cluster complexes are moderately phosphorescent in the fluid CH2Cl2 solution, but exhibit highly intense phosphorescent emission in solid state and film. As revealed by theoretical computational studies, the phosphorescence is ascribable to significant 3[π (aromatic acetylide) → s/p (Au)] 3LMCT parentage with a noticeable Au4Ag2 cluster centered 3[d → s/p] triplet state. Taking advantage of mCP and OXD‐7 as a mixed host with 20 wt% dopant of phosphorescent Au4Ag2 cluster complex in the emitting layer, solution‐processed organic light‐emitting diodes (OLEDs) exhibit highly efficient electrophosphorescence with the maximum current, power, and external quantum efficiencies of 24.1 cd A−1, 11.6 lm W−1, and 7.0%, respectively. Introducing copper(I) thiocyanate (CuSCN) as a hole‐transporting layer onto the PEDOT:PSS hole‐injecting layer through the orthogonal solution process induces an obvious improvement of the device performance with lower turn‐on voltage and higher electroluminescent efficiency.

Quaternary Phosphorus‐Induced Iodocuprate(I)‐Based Hybrids: Water Stabilities, Tunable Luminescence and Photocurrent Responses

“…At longer wavelengths over 350 nm, relatively weaker absorption bands are observed, which are not observed for the free ligands. These adsorptions are relevant to ligand‐to‐ligand charge transfer (LLCT) and charge transfer between inorganic iodocuprates and organic moieties . The former transitions can be validated by their obvious π–π and C–H ··· π interactions in their lattices, and the latter charge transfers have already been reported …”

Green‐Light‐Emitting Diodes based on Tetrabromide Manganese(II) Complex through Solution Process

“…[35][36][37] For nondoped devices ( Figure S3, Supporting Information), an aqueous poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) was first spin coated on indium tin oxide (ITO) glass substrates, followed by the overlaying of a holetransport layer such as 4,4′-bis(carbazol-9-yl)biphenyl (CBP), 1,3-bis(carbazole-9-yl)benzene (mCP), or 4,4′,4″-tri(9-carbazoyl)tripheylamine (TCTA) dissolved in CH 2 Cl 2 . [35][36][37] For nondoped devices ( Figure S3, Supporting Information), an aqueous poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) was first spin coated on indium tin oxide (ITO) glass substrates, followed by the overlaying of a holetransport layer such as 4,4′-bis(carbazol-9-yl)biphenyl (CBP), 1,3-bis(carbazole-9-yl)benzene (mCP), or 4,4′,4″-tri(9-carbazoyl)tripheylamine (TCTA) dissolved in CH 2 Cl 2 .…”

Copper (I) Selenocyanate (CuSeCN) as a Novel Hole‐Transport Layer for Transistors, Organic Solar Cells, and Light‐Emitting Diodes

“…CuSCN is a molecular compound from the metal pseudohalide family, and is a wide bandgap (>3.4 eV) semiconductor with a field‐effect hole mobility in the range of 0.01–0.1 cm 2 V −1 s −1 . This p‐type material has been successfully utilized in a variety of device types including thin‐film transistors (TFTs), OLEDs, OPVs, and metal halide perovskite solar cells . Other inorganic p‐type semiconductors such as hole‐transporting metal oxides offer an alternative to metal pseudohalides; examples include copper oxide (Cu 2 O), tin monoxide (SnO), and the aforementioned NiO x .…”