High-Efficiency Green Organic Light-Emitting Devices Utilizing Phosphorescent Bis-cyclometalated Alkynylgold(III) Complexes

Abstract

A new phosphorescent material of cyclometalated alkynylgold(III) complex, [Au(2,5-F(2)C(6)H(3)-C∧N∧C)(C≡C-C(6)H(4)N(C(6)H(5))(2)-p)] (1) (2,5-F(2)C(6)H(3)-HC∧N∧CH = 2,6-diphenyl-4-(2,5-difluorophenyl)pyridine), has been synthesized, characterized, and its device performance investigated. This luminescent gold(III) complex was found to exhibit rich PL and EL properties and has been utilized as phosphorescent dopants of OLEDs. At an optimized dopant concentration of 4%, a device with a maximum external quantum efficiency (EQE) of 11.5%, corresponding to a current efficiency of 37.4 cd/A and a power efficiency of 26.2 lm/W, has been obtained. Such a high EQE is comparable to that of Ir(ppy)(3)-based devices. The present work suggests that the alkynylgold(III) complex is a promising phosphorescent material in terms of both efficiency and thermal stability, with the additional advantages of its relatively inexpensive cost and low toxicity.

Cluster–π electronic interaction in a superatomic Au13 cluster bearing σ-bonded acetylide ligands

“…[15][16][17][18] Tsukuda et al have observed no appreciable electronic interaction in the optical absorption spectra of alkyne-protected gold clusters of diameter > 1 nm. 15,16 We have also demonstrated a similar phenomenon for a structurally precise Au 8 cluster with an anisotropic core+exo-type structure. 17 Herein we report the first experimental evidence of electronic interaction between a polyhedral gold core and a σ-bonded π-unit in the absorption spectrum of a phenylethynyl-modified Au 13 cluster with an icosahedral geometry and superatomic 8-electron system.…”

Cyclometalated Gold(III) Complexes: Synthesis, Reactivity, and Physicochemical Properties

“…[27][28][29][30] In dichloromethane at room temperature,t he [(C^N^C)Au III (alkynyl)] complexes 5a-f are luminescent at l = 468-611 nm upon excitation at l ! [32,33] Interestingly,complex 7chas also been successfully applied in the fabrication of memory devices with high ON/OFF ratios,l ong retention times,a nd good stability. [31] These complexes have continued to receive increasing attention owing to their potential use in the context of light-emitting devices.I n Figure 1, representative examples of improved members of this compound class are depicted.…”

Luminescent Bis‐Cyclometalated Gold(III) Complexes with Alkynyl Ligands of Hexaphenylbenzene and Hexabenzocoronene Derivatives and Their Supramolecular Assembly

“…For complexes 1-7 and 9-10,t he low-energya bsorption bands at l = 364-412 nm are quite sensitivet ot he nature of the bis-cyclometalating ligands. The vibrational progressional spacings of 1200-1400 cm À1 are in close agreementw ith the skeletal vibrational frequency of the bis-cyclometalating ligands.W ith reference to the electronic absorption studies of the related bis-cyclometalated alkynylgold(III) complexes in the literature, [25][26][27][28][29][32][33][34][35][36][37][38][39] the low-energy absorptions for complexes 1-7 and 9-10 are assigned as metal-perturbed p-p*i ntraligand (IL) transitions of the bis-cyclometalating ligand, probably involving some charge-transfer character from the phenyl moiety to the pyridine unit.…”

“…[24] This class of stable gold(III) complexes is the first example of organogold(III) compounds that emit not only at low temperatures, but also in solution at ambient temperature. [24] Our group also reported several classes of stable cyclometalated gold(III) complexes with strongly s-donating alkynyl [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and N-heterocyclic carbene ligands, [40] which exhibit rich luminescence properties in various media at both low and room temperature. In particular,t he alkynyl group with ar igid structure, linear geometry,a nd extended pconjugated system is an ideal candidate fort he construction of organometallicc ompounds because of its ability to communicate electronically with the metal center through p bonding.…”