Photochemistry and Luminescence of Cyclometallated Complexes

Today organic light emitting diodes are a topic of significant academic and industrial research interest. OLED technology is used in commercially available displays, and efforts have been directed to improve this technology. Design and synthesis of phosphorescent based transition metals are capable of harvesting both singlet and triplet excitons and achieve 100 % internal quantum efficiency is an active area of research. Among all the transition metals, iridium is considered a prime candidate for OLEDs due to its prominent photophysical characteristics. In the present review, we have concentrated on the Iridium based homo and heteroleptic complexes that have dissimilar substitutions on phenylpyridine ligands, different ancillary ligands and the effect of substitution on HOMO/LUMO energies and a brief discussion and correlation on the photophysical, electrochemical and device performances of the different complexes have been reviewed for organic light emitting diodes.

show abstract

“…The cyclometalated Ir complexes provide distinct features applicable to phosphorescent dopants used in the OLEDs ,…”

Section: Introductionmentioning

confidence: 99%

Structural Mimics of Phenyl Pyridine (ppy) – Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes – An Overview

Kajjam

Vaidyanathan

2017

The Chemical Record

View full text Add to dashboard Cite

show abstract

“…Important is also the energy difference between excited singlet and triplet states that are spin-orbit coupled. 1,4,[25][26][27][28][29] In order to obtain suitable candidate materials for future applications, a reliable computational screening procedure covering a large number of ligands and combinations thereof would be highly rewarding. 24 In the past, pseudo-square planar platinum (II) and pseudo-octahedral iridium (III) complexes have shown to be excellent emitter materials for phosphorescent OLEDs and were synthesized with a variety of organic ligands.…”

Section: Introductionmentioning

confidence: 99%

Charge-transfer excited states in phosphorescent organo-transition metal compounds: a difficult case for time dependent density functional theory?

2015

View full text Add to dashboard Cite

Figure 0: TOC Entry -Synopsis: A series of 17 platinum (II) and iridium (III) complexes have been investigated theoretically and experimentally to elucidate the charge-transfer character in emission from the lowest triplet state. Time-dependent density functional theory is found to be surprisingly accurate for metal-to-ligand transitions. ABSTRACTLight emitting organo-transition metal complexes have found widespread use in the past. The computational modelling of such compounds is often based on time-dependent density functional theory (TDDFT), which enjoys popularity due to its numerical efficiency and simple black-box character. It is well known, however, that TDDFT notoriously underestimates energies of charge-transfer excited states which are prominent in phosphorescent metal-organic compounds. In this study, we investigate whether TDDFT is providing a reliable description of the electronic properties in these systems. To this end, we compute 0-0 triplet state energies for a series of 17 pseudo-square planar platinum (II) and pseudo-octahedral iridium (III) complexes that are known to feature quite different localization * characteristics ranging from ligand-centered (LC) to metal-to-ligand charge transfer (MLCT) transitions. The calculations are performed with conventional semi-local and hybrid functionals as well as with optimally tuned range-separated functionals that were recently shown to overcome the charge transfer problem in TDDFT. We compare our results against low temperature experimental data and propose a criterion to classify excited states based on wave function localization. In addition, singlet absorption energies and singlet-triplet splittings are evaluated for a subset of the compounds and are also validated against experimental data. Our results indicate that for the investigated complexes charge-transfer is much less pronounced than previously believed.

show abstract

“…It is not the aim of this section to discuss all these aspects (see reviews in [9,27,44,83,[122][123][124][125][126][127][128][129][130][131][132][133]). Here, it is mainly focused on properties of the lower electronically excited states (and the ground state).…”

Section: [Ru(bpy)~] ~+mentioning

confidence: 99%

Characterization of excited electronic and vibronic states of platinum metal compounds with chelate ligands by highly frequency-resolved and time-resolved spectra

Yersin

Humbs

Strasser

Topics in Current Chemistry

View full text Add to dashboard Cite

The lowest excited electronic states of triplet character and related vibronic properties are discussed in detail on the basis of highly frequency-resolved and time-resolved emission and excitation spectra of per-protonated, per-deuterated, and partially deuterated [Pt(bpy)2] 2+, [Rh(bpy)3] 3+, [Ru(bpy)3] 2+, and [Os(bpy)3] ~+. Emphasis is placed on the use of the enormous amount of information displayed in well-resolved vibrational satellite structures. For comparison, IR data and Raman spectra are also used. In addition, data are given for [Ru(bpz)Pt(3-thpy) 2, Pt(2-thpy)(CO)(Cl), Pt(2-thpy) 2, Pt(qol)2, Pt(qtl)2. Trends and effects are also addressed, which are related to the amount of metal d-orbital mixing. In particular, we discuss the role of traps and sites in the context of high-resolution, site-selective, and line-narrowed spectra of chromophores doped into matrices; the interplay between states of ligand-centered 3rtrr* and ~MLCT character; localization versus delocalization behavior; radiative decay properties; zero-field splittings; spin-lattice relaxations via direct and Orbach mechanisms; Arrhenius behavior after time delay; Franck-Condon activities and Huang-Rhys factors; Franck-Condon versus Herzberg Teller activities and tunability of these activities under high magnetic fields; isotope marking and deuteration effects; aggregate formation of [Ru(bpy)3]2+; and radiationless energy transfer in neat [Ru(bpy)3](PF6) 2. These effects are in part treated in detail, but the aim is to use easy-to-follow descriptions. In particular, it is emphasized throughout this review that chemical tunability opens fascinating possibilities for controlled variation of physical properties.

show abstract

Photochemistry and Luminescence of Cyclometallated Complexes

Cited by 149 publications

References 116 publications

Structural Mimics of Phenyl Pyridine (ppy) – Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes – An Overview

Structural Mimics of Phenyl Pyridine (ppy) – Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes – An Overview

Charge-transfer excited states in phosphorescent organo-transition metal compounds: a difficult case for time dependent density functional theory?

Characterization of excited electronic and vibronic states of platinum metal compounds with chelate ligands by highly frequency-resolved and time-resolved spectra

Contact Info

Product

Resources

About