Osmium‐ and Ruthenium‐Based Phosphorescent Materials: Design, Photophysics, and Utilization in OLED Fabrication

Abstract

Keywords: Osmium / Ruthenium / N ligands / Phosphorescence / Luminescence Osmium(II) complexes possessing β-diketonate, quinolinate, diimine, and C-linked pyridyl azolate chelates reveal interesting structural and photophysical properties. Spectroscopic and dynamic measurements, in combination with theoretical analyses, have provided an important understanding of the electronically excited state properties of these complexes, such as the energy gap and nature of the lower lying states, rate for intersystem crossing, and the efficiency of corresponding radiative decay and nonradiative deactivation processes. This review also reports on the synthetic processes

Spectroscopic and Computational Study on New Blue Emitting ReL(CO)3Cl Complexes Containing Pyridylimidazo[1,5‐a]pyridine Ligands

“…[4,5] This class of ligands has emission in the blue region of the visible range (450-470 nm), which is a desirable, but critical, feature in OLED technology. In a previous paper [1] we discussed the synthesis and the photophysical properties of new rhenium complexes containing 1-pyridylimidazo [1,5-a]pyridine ligands with electron-donor groups on a phenyl substituent.…”

Emissive or Nonemissive? A Theoretical Analysis of the Phosphorescence Efficiencies of Cyclometalated Platinum(II) Complexes

“…6 Table S14 Table S8 in the Supporting Information), and these occupied d orbitals are different from that of the T 1 excited state (d xz orbital). Hence, the S 2 , S 3 , and S 4 excited states can have effective SOC with the T 1 excited state.…”

“…As the energy separation between the spin-orbit-coupled S n and T m excited states has been correlated to the energy difference between the occupied d orbitals, [20,21] it has been reasoned that the closer the different occupied d orbitals are (the energy difference between two different occupied d orbitals is denoted Ddd occ ), the larger the H SOC matrix element and the faster the radiative decay rate constant k r will be, according to Equation (3). Indeed, the energetically closer proximity of the occupied d orbitals in the quasi-octahedral d 6 Ir III complexes (the t 2g orbitals) compared with the quasisquare planar d 8 Pt II complexes (d s and d p orbitals) has been put forward as the reason why the former are usually more intense emitters than the latter. [20,21] Thus, it is of interest to evaluate the d-orbital splittings between the two different highest lying occupied d orbitals (Ddd occ ) and the dd* splitting for 1-5.…”

Red Phosphorescence in RuII Complexes of a Tridentate N‐Heterocyclic Carbene Ligand Incorporating Tetrahydropyrimidine

“…The red emission of these complexes compares favourably to the solid-state phosphorescence of Ru II complexes made with tridentate pyrazolyl bis(pyridine) ligands (666-810 nm), [56] which are also used in phosphorescent organic light-emitting diodes. [57,58] …”