Triplet harvesting in luminescent Cu(i) complexes by the thermally activated luminescence transition mechanism: impact of the molecular structure

2017 ◽  
Vol 5 (18) ◽  
pp. 4488-4494 ◽  
Author(s):  
Z. C. Su ◽  
C. C. Zheng ◽  
G. Cheng ◽  
C.-M. Che ◽  
S. J. Xu
Keyword(s):  
Molecular Structure ◽  
Variable Temperature ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Induced ◽  
Thermally Activated ◽  
Transition Mechanism ◽  
Time Resolved Photoluminescence ◽  
Temperature Time ◽  
Triplet Harvesting

Thermally induced transition from ordinary phosphorescence to delayed fluorescence in two kinds of luminescent copper(i) complexes is comprehensively investigated by using variable-temperature time-integrated and time-resolved photoluminescence measurements as well as model analysis.

scholarly journals Direct observation of intersystem crossing in a thermally activated delayed fluorescence copper complex in the solid state

2016 ◽  
Vol 2 (1) ◽  
pp. e1500889 ◽  
Author(s):  
Larissa Bergmann ◽  
Gordon J. Hedley ◽  
Thomas Baumann ◽  
Stefan Bräse ◽  
Ifor D. W. Samuel
Keyword(s):  
Solid State ◽  
Delayed Fluorescence ◽  
Average Lifetime ◽  
Intersystem Crossing ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Singlet States ◽  
Time Resolved Photoluminescence

Intersystem crossing in thermally activated delayed fluorescence (TADF) materials is an important process that controls the rate at which singlet states convert to triplets; however, measuring this directly in TADF materials is difficult. TADF is a significant emerging technology that enables the harvesting of triplets as well as singlet excited states for emission in organic light emitting diodes. We have observed the picosecond time-resolved photoluminescence of a highly luminescent, neutral copper(I) complex in the solid state that shows TADF. The time constant of intersystem crossing is measured to be 27 picoseconds. Subsequent overall reverse intersystem crossing is slow, leading to population equilibration and TADF with an average lifetime of 11.5 microseconds. These first measurements of intersystem crossing in the solid state in this class of mononuclear copper(I) complexes give a better understanding of the excited-state processes and mechanisms that ensure efficient TADF.

Highly efficient electroluminescence from purely organic donor–acceptor systems

2015 ◽  
Vol 87 (7) ◽  
pp. 627-638 ◽  
Author(s):  
Katsuyuki Shizu ◽  
Jiyoung Lee ◽  
Hiroyuki Tanaka ◽  
Hiroko Nomura ◽  
Takuma Yasuda ◽  
...  
Keyword(s):  
Energy Difference ◽  
Delayed Fluorescence ◽  
Large Contribution ◽  
Time Resolved ◽  
Light Emitting ◽  
Thermally Activated ◽  
Highly Efficient ◽  
Type Molecule ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence

AbstractThermally activated delayed fluorescence (TADF) emitters are third-generation electroluminescent materials that realize highly efficient organic light-emitting diodes (OLEDs) without using rare metals. Here, after briefly reviewing the principles of TADF and its use in OLEDs, we report a sky-blue TADF emitter, 9-(4-(benzo[d]thiazol-2-yl)phenyl)-N3,N3,N6,N6-tetraphenyl-9H-carbazole-3,6-diamine (DAC-BTZ). DAC-BTZ is a purely organic donor–acceptor-type molecule with a small energy difference between its lowest excited singlet state and lowest triplet state of 0.18–0.22 eV according to fluorescence and phosphorescence spectra of a DAC-BTZ-doped film. In addition, the doped film exhibits a high photoluminescence quantum yield of 0.82. Time-resolved photoluminescence measurements of the doped film confirm that DAC-BTZ emits TADF. An OLED containing DAC-BTZ as an emitter exhibits a maximum external quantum efficiency (EQE) of 10.3%, which exceeds those obtained with conventional fluorescent emitters (5–7.5%). TADF from DAC-BTZ makes a large contribution to the high EQE of its OLED.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

scholarly journals Thermally activated delayed fluorescence vs. room temperature phosphorescence by conformation control of organic single molecules

2019 ◽  
Vol 7 (22) ◽  
pp. 6616-6621 ◽  
Author(s):  
Przemyslaw Data ◽  
Masato Okazaki ◽  
Satoshi Minakata ◽  
Youhei Takeda
Keyword(s):  
Room Temperature ◽  
Single Molecules ◽  
Delayed Fluorescence ◽  
Room Temperature Phosphorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Molecular Conformations ◽  
Thermally Activated ◽  
Luminescent Compound

The time-resolved photophysical analysis of a multi-color-changing mechanochromic luminescent compound has been disclosed, which reveals distinct different emission paths to boost TADF and RTP of the emitter depending on its molecular conformations.

Tuning the excited-state deactivation pathways of dinuclear ruthenium(ii) 2,2′-bipyridine complexes through bridging ligand design

2020 ◽  
Vol 49 (24) ◽  
pp. 8096-8106 ◽  
Author(s):  
Simon Cerfontaine ◽  
Ludovic Troian-Gautier ◽  
Sara A. M. Wehlin ◽  
Frédérique Loiseau ◽  
Emilie Cauët ◽  
...  
Keyword(s):  
Excited State ◽  
Steady State ◽  
Variable Temperature ◽  
Ligand Design ◽  
Binuclear Complexes ◽  
Time Resolved ◽  
Bridging Ligand ◽  
Dinuclear Ruthenium ◽  
Photophysical Study ◽  
Time Resolved Photoluminescence

A detailed photophysical study of binuclear complexes was performed using steady-state and time-resolved photoluminescence measurements at variable temperature. The results were compared with the prototypical [Ru(bpy)3]2+.

Triplet Harvesting with 100% Efficiency by Way of Thermally Activated Delayed Fluorescence in Charge Transfer OLED Emitters

2013 ◽  
Vol 25 (27) ◽  
pp. 3707-3714 ◽  
Author(s):  
Fernando B. Dias ◽  
Konstantinos N. Bourdakos ◽  
Vygintas Jankus ◽  
Kathryn C. Moss ◽  
Kiran T. Kamtekar ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Triplet Harvesting

Transfer printing of polymer light-emitting devices with a small molecular seeding layer featuring thermally activated delayed fluorescence for triplet harvesting

2020 ◽  
Vol 5 (1) ◽  
pp. 144-149 ◽  
Author(s):  
Yang Tang ◽  
Yuhan Gao ◽  
Guohua Xie ◽  
Chuluo Yang
Keyword(s):  
Delayed Fluorescence ◽  
Transfer Printing ◽  
Printing Technology ◽  
Seeding Layer ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Thermally Activated ◽  
Polymer Light Emitting Devices ◽  
Triplet Harvesting

Transfer-printing technology combined with a TADF-based HTL realized a 2-fold enhancement of EL efficiency for a polymer fluorescence emitter.

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