Molecular-engineered [Ir(Fppy)₂(Mepic)] towards efficient blue-emission

Abstract

A novel Ir(III) complex, [Ir(Fppy) 2 (Mepic)] (Fppy = 2-(2,4-difluorophenyl)pyridinate; Mepic = 3-methylpyridine-2-carboxylate) was engineered to show a blue phosphorescence with an impressive unitary quantum yield in our search for luminescent metal complexes for low cost displays and efficient lighting devices. Application of the Golden Rule through Franck-Condon spectral analyses along with TD-DFT calculations and comparisons to the [Ir(Fppy) 2 (pic)] complex have provided insights on the mixing extension between charge-transfer (CT) and ligand-centered (LC) excited states in the emissive lowest-energy triplet transition for different media. The relatively narrow and vibronically-structured emission of [Ir(Fppy) 2 (Mepic)] at 298 K mainly arises from a spin-orbit-induced mixed 3 MLCT-LC Ir(Fppy)→Fppy / 3 LLCT Fppy→Mepic excited state, with an enhanced MLCT character because of the methyl addition to pic. In a frozen media at 77 K, the CT contribution is extinguished, leading to a pure LC Fppy emission, with similar emissive spectral profile to the free ligand, FppyH. The efficient A detailed photophysical investigation of [Ir(Fppy) 2 (Mepic)] by TD-DFT and FrankCondon emission band shape analyses revealed a succeeded molecular engineering towards an intensified blue emission, with phosphorescence from a spin-orbit-induced mixed 3 MLCT-LC Ir(Fppy)→Fppy / 3L LCT Fppy→Mepic excited state and an impressive unitary quantum yield.

Ir(iii) complexes designed for light-emitting devices: beyond the luminescence color array

“…[29][30][31][32][33][34][35][36][37][38][39][40] In this Perspective, we report recent breakthroughs and the state of the art on highlyefficient emissive Ir(III) complexes including a personal account elucidating the role of 3 molecular and electronic structure in controlling the photophysics of heteroleptic Ir(III) compounds of importance in light-emitting devices. 28,29,40,41 …”

“…40 A device was recently fabricated in a simple FTO/PEDOT:PSS/PVK:complex/Al architecture (PVK = polyvinylcarbazole) and led to an intense blue-emission, as depicted in Figure 7A. 135 A slight modification on the working mechanism of OLEDs by using highly concentrated mobile ions (lithium triflate) in the organic active layer led to the development of the first LEC by Pei et al, in 1995.…”

“…Their first lowest-energy singlet transition (S 1 ) results from an orbital promotion from the HOMO to a π* (L^X) LUMO, and has been assigned to a MLCT state with LLCT mixing. 29,34,40,84 The wave function ( S1 ) for these MLCT-based S 1 states can be considered as a combination of spin () and spatial parts () ofthe d-and -orbital wave functions, (A) HOMO and LUMO electron contours, (B) orbital energies calculated by TD-DFT and (C) experimental redox potentials for the [Ir(Rppy) 2 (N^N)] + series. Adapted from reference 29 .…”

Dispositivos moleculares para conversão de energia: filmes compactos de TiO>sub<2>/sub< em DSPECs e complexos de Ir(III)

“…18 Exemplos 22,140 . Complexos de Ir(III) com ligantes do tipo picolinato, 73,131,145 usualmente apresentam rendimentos quânticos bastante elevados, como no caso do consagrado [Ir(Fppy)2pic] (ϕ > 60%) 131…”

“…148-150 em modos vibrônicos. O efeito rigidocrômico foi reportado para outros complexos de Ir(III),18,47,72,73,151,152 comparando, no entanto, apenas aspectos em meio fluido e em meio vítreo. No presente trabalho, realizou-se, pela primeira vez, um estudo com complexos polipiridínicos de Ir(III) em três meios distintos, em que se Parâmetros espectrais de emissão dos complexos em diferentes meios.…”