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

Abstract

In pursuing novel efficient lighting technologies and materials, phosphorescent cyclometallated Ir(iii) complexes have been prominent due to their wide color arrays and highly efficient electroluminescence. Their photophysical properties are strongly influenced by spin-orbit coupling exerted by the iridium core, usually resulting in intense, short-lived emission, which can be systematically tuned as a triumph of molecular engineering. This Perspective aims to present recent breakthroughs and state of the art on emissive Ir(iii) compounds, in particular a personal account on heteroleptic [Ir(N^C)2(L^X)](+) complexes, addressing the mechanistic concepts behind their luminescence. Their fascinating photophysical properties strengthen application in more-efficient light-emitting technologies, such as organic light-emitting diodes and light-emitting electrochemical cells.

Encapsulation and Enhanced Luminescence Properties of IrIII Complexes within a Hexameric Self‐Assembled Capsule

“…[16] Al igand-centered (LC) emission from at riplet excited state is usually media-independent with as tructured spectrum, while the metal-to-ligand chargetransfer (MLCT) emission from at riplet excited state resultsi n ab road spectrum, which is highly sensitive to the polaritya nd rigidity of the medium such as solventa nd matrix. [16] Al igand-centered (LC) emission from at riplet excited state is usually media-independent with as tructured spectrum, while the metal-to-ligand chargetransfer (MLCT) emission from at riplet excited state resultsi n ab road spectrum, which is highly sensitive to the polaritya nd rigidity of the medium such as solventa nd matrix.…”

“…The emission spectrum of [2'3]Cl (10 mm)s howed al arge blue shift (Dl = 27 nm) from that of [3]Cl under this condition. [16] Thus, we assumed that the blue shift wasp robably caused by the rigid environ- Figure 2. [16] Thus, we assumed that the blue shift wasp robably caused by the rigid environ- Figure 2.…”

Photochemistry of [Ru(pytz)(btz)2]2+ and Characterization of a κ1-btz Ligand-Loss Intermediate

“…Significant efforts have therefore focused on the design of ligands for these complexes in order to maximise their light absorbing 9 and/or emissive properties. 10 The excited states in these complexes responsible for solar cell sensitisation or light emission, for example, are 3 MLCT states. Efficiency loss processes for phosphorescent emitters often involve higher-lying 3 MC states which, when in close enough energetic proximity, can be thermally populated from photoexcited 3 MLCT states.…”

About the electronic and photophysical properties of iridium(iii)-pyrazino[2,3-f][1,10]-phenanthroline based complexes for use in electroluminescent devices

“…Due to strong metal-induced spin orbit coupling (SOC) processes, these complexes populate the spinforbidden triplet excited states to obtain high emission quantum yields 4,7 . In addition, these compounds show different emission (and absorption) wavelengths, which are controlled by including different ligands in the molecular design 8 . According to this description, these complexes are used in solid state lighting systems such as organic lightemitting diodes (OLEDs) and light emitting electrochemical cells (LECs) [9][10][11][12] ; moreover, the luminescent properties of Ir III complexes turn them in efficient candidates for development of scintillating materials for radiation detection 13,14 .…”