A hybridized local and charge transfer excited state for solution-processed non-doped green electroluminescence based on oligo(p-phenyleneethynylene)

2020 ◽  
Vol 8 (24) ◽  
pp. 8047-8060
Author(s):  
Hakan Usta ◽  
Dilek Alimli ◽  
Resul Ozdemir ◽  
Emine Tekin ◽  
Fahri Alkan ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Solution Processed

A novel oligo(p-phenyleneethynylene)-based hot-exciton molecule with hybridized local and charge transfer (HLCT) excited states was developed to yield high radiative exciton yields in OLEDs.

A density functional theory and spectroscopic study of intramolecular quenching of metal-to-ligand charge-transfer excited states in some mono-bipyridine ruthenium(II) complexes

2014 ◽  
Vol 92 (10) ◽  
pp. 996-1009 ◽  
Author(s):  
Shivnath Mazumder ◽  
Ryan A. Thomas ◽  
Richard L. Lord ◽  
H. Bernhard Schlegel ◽  
John F. Endicott
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Lower Energy ◽  
Density Functional ◽  
Dimethyl Sulfide ◽  
Intramolecular Electron Transfer ◽  
Functional Theory ◽  
Ligand Charge Transfer

The complexes [Ru(NCCH3)4bpy]2+ and [Ru([14]aneS4)bpy]2+ ([14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane, bpy = 2,2′-bipyridine) have similar absorption and emission spectra but the 77 K metal-to-ligand charge-transfer (MLCT) excited state emission lifetime of the latter is less than 0.3% that of the former. Density functional theory modeling of the lowest energy triplet excited states indicates that triplet metal centered (3MC) excited states are about 3500 cm−1 lower in energy than their 3MLCT excited states in both complexes. The differences in excited state lifetimes arise from a much larger coordination sphere distortion for [Ru(NCCH3)4bpy]2+ and the associated larger reorganizational barrier for intramolecular electron transfer. The smaller ruthenium ligand distortions of the [Ru([14]aneS4)bpy]2+ complex are apparently a consequence of stereochemical constraints imposed by the macrocyclic [14]aneS4 ligand, and the 3MC excited state calculated for the unconstrained [Ru(S(CH3)2)4bpy]2+ complex (S(CH3)2 = dimethyl sulfide) is distorted in a manner similar to that of [Ru(NCCH3)4bpy]2+. Despite the lower energy calculated for its 3MC than 3MLCT excited state, [Ru(NCCH3)4bpy]2+ emits strongly in 77 K glasses with an emission quantum yield of 0.47. The emission is biphasic with about a 1 μs lifetime for its dominant (86%) emission component. The 405 nm excitation used in these studies results in a significant amount of photodecomposition in the 77 K glasses. This is a temperature-dependent biphotonic process that most likely involves the bipyridine-radical anionic moiety of the 3MLCT excited state. A smaller than expected value found for the radiative rate constant is consistent with a lower energy 3MC than 3MLCT state.

scholarly journals Excited States and Intermediates by Time-Resolved Infrared Spectroscopy

1999 ◽  
Vol 19 (1-4) ◽  
pp. 245-251 ◽  
Author(s):  
J. J. Turner ◽  
M. W. George ◽  
I. P. Clark ◽  
I. G. Virrels
Keyword(s):  
Infrared Spectroscopy ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Fast Time ◽  
Time Resolved ◽  
Excited Species ◽  
Charge Transfer Transitions ◽  
Time Resolved Infrared Spectroscopy ◽  
Kinetics Of

For coordination compounds containing CO or CN groups, fast time-resolved infrared spectroscopy (TRIR) provides a convenient method of probing excited states and intermediates. TRIR has proved particularly powerful for probing the structure and kinetics of organometallic intermediates. The interpretation is particularly straightforward when combined with IR data from matrix isolation experiments, although there can be some subtle differences. In excited state studies, shifts in ν(CO) and ν(CN) frequencies, from ground to excited state, are sensitive to the changes in electron distribution on excitation, thus allowing the distinction between charge-transfer and non-charge-transfer transitions. Subtle effects on excited state ν(CO) band positions occur with change from fluid to rigid solvent-“infrared rigidochromism”. There is often a change in ν(CO) band width on excitation; this can be interpreted in terms of specific interactions between the excited species and the solvent. This paper presents some of our recent work in this area.

scholarly journals Improved charge transfer multiplet method to simulateM- andL-edge X-ray absorption spectra of metal-centered excited states

2018 ◽  
Vol 25 (5) ◽  
pp. 1600-1608 ◽  
Author(s):  
Kaili Zhang ◽  
Gregory S. Girolami ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Transition Metal Complexes ◽  
Software Package ◽  
Spin Crossover ◽  
Difference Spectra ◽  
X Ray ◽  
Spectroscopic Signatures ◽  
X Ray Absorption

Charge transfer multiplet (CTM) theory is a computationally undemanding and highly mature method for simulating the soft X-ray spectra of first-row transition metal complexes. However, CTM theory has seldom been applied to the simulation of excited-state spectra. In this article, theCTM4XASsoftware package is extended to simulateM2,3- andL2,3-edge spectra for the excited states of first-row transition metals and also interpret CTM eigenfunctions in terms of Russell–Saunders term symbols. These new programs are used to reinterpret the recently reported excited-stateM2,3-edge difference spectra of photogenerated ferrocenium cations and to propose alternative assignments for the electronic state of these cations responsible for the spectroscopic features. These new programs were also used to model theL2,3-edge spectra of FeIIcompounds during nuclear relaxation following photoinduced spin crossover and to propose spectroscopic signatures for their vibrationally hot states.

STUDY OF THE S1 AND S2 EXCITED STATES OF GAS-PHASE PROTONATED SCHIFF BASE RETINAL CHROMOPHORES IN ONE AND TWO PHOTON ABSORPTION

2011 ◽  
Vol 10 (02) ◽  
pp. 121-132 ◽  
Author(s):  
YUANZUO LI ◽  
PENG SONG ◽  
YING SHI ◽  
YONG DING ◽  
FENGJIE ZHOU ◽  
...  
Keyword(s):  
Schiff Base ◽  
Excited State ◽  
Charge Transfer ◽  
Gas Phase ◽  
Excited States ◽  
Density Functional ◽  
Three Dimensional ◽  
Photon Absorption ◽  
Two Photon ◽  
The One

The S1 and S2 excited states of gas-phase protonated Schiff base retinal chromophores in the one- and two-photon absorptions (TPAs) are investigated with time-dependent density functional theory. In one-photon absorption, the two-dimensional (2D) site and three-dimensional (3D) cube representations reveal that S1 and S2 excited states of gas-phase protonated Schiff base retinal chromophores are all charge transfer excited states. To better study the weak S2 excited states of gas-phase protonated Schiff base retinal chromophores, we investigated theoretically excited state properties of them in TPA. For 11-cis dimethyl retinal, it is found that the cross section of S2 excited state is 51.04 GM in PTA, which is only slightly smaller than that of S1 (77.04 GM) in TPA. Therefore, the S2 excited state of 11-cis dimethyl retinal can be clearly observed in TPA experiment. The 2D site and 3D cube representations reveal that electronic transition from S1 to S2 excited state of gas-phase protonated Schiff base retinal chromophores in TPA are also of charge transfer character.

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