Phosphorescence or Thermally Activated Delayed Fluorescence? Intersystem Crossing and Radiative Rate Constants of a Three-Coordinate Copper(I) Complex Determined by Quantum-Chemical Methods

2016 ◽  
Vol 55 (15) ◽  
pp. 7508-7516 ◽  
Author(s):  
Jelena Föller ◽  
Martin Kleinschmidt ◽  
Christel M. Marian
Keyword(s):  
Rate Constants ◽  
Quantum Chemical ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Chemical Methods ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Quantum Chemical Methods ◽  
Radiative Rate

Intramolecular H-bond design for efficient orange–red thermally activated delayed fluorescence based on a rigid dibenzo[f,h]pyrido[2,3-b]quinoxaline acceptor

2020 ◽  
Vol 8 (44) ◽  
pp. 15728-15734
Author(s):  
Feng-Ming Xie ◽  
Xin-Yi Zeng ◽  
Jing-Xiong Zhou ◽  
Zhi-Dong An ◽  
Wenjun Wang ◽  
...  
Keyword(s):  
Excited State ◽  
Rate Constants ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Molecular Excited State

Tune the molecular excited state and rate constants of radiative intersystem crossing by constructing intramolecular H-bonds to achieve high-efficiency orange–red TADF-OLEDs.

All-organic fast intersystem crossing assisted exciplexes exhibiting sub-microsecond thermally activated delayed fluorescence

2021 ◽  
Author(s):  
Kaspars Traskovskis ◽  
Armands Sebris ◽  
Irina Novosjolova ◽  
Maris Turks ◽  
Matas Guzauskas ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Novel Strategy

A novel strategy is presented towards acquisition of exciplex systems exhibiting thermally activated delayed fluorescence (TADF) with high reverse intersystem crossing (RISC) rate (exceeding 107 s-1). This approach involves constructing...

A quantitative description of photoluminescence efficiency of a carbazole-based thermally activated delayed fluorescence emitter

2019 ◽  
Vol 43 (15) ◽  
pp. 6032-6039
Author(s):  
Songyan Feng ◽  
Xugeng Guo ◽  
Jinglai Zhang
Keyword(s):  
Quantitative Description ◽  
Energy Difference ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Small Energy ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Fluorescence Efficiency ◽  
High Fluorescence ◽  
Photoluminescence Efficiency

The present results reveal that the dominant charge transfer characteristics in the S1 and T1 states produce a small energy difference between the two states, and consequently an efficient reverse intersystem crossing process and a high fluorescence efficiency.

Over 20% external quantum efficiency in red thermally activated delayed fluorescence organic light-emitting diodes using a reverse intersystem crossing activating host

2018 ◽  
Vol 6 (20) ◽  
pp. 5363-5368 ◽  
Author(s):  
Ji Han Kim ◽  
Dong Ryun Lee ◽  
Si Hyun Han ◽  
Jun Yeob Lee
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light

Highly efficient red thermally activated delayed fluorescence organic light-emitting diodes were developed using a reverse intersystem crossing activating host derived from phenylcarbazole and pyridofuropyridine.

scholarly journals Exact Solution of Kinetic Analysis for Thermally Activated Delayed Fluorescence Materials

2021 ◽  
Author(s):  
Youichi Tsuchiya ◽  
Stefan Diesing ◽  
Fatima Bencheikh ◽  
Yoshimasa Wada ◽  
Paloma dos Santos ◽  
...  
Keyword(s):  
Rate Constants ◽  
A Priori ◽  
Delayed Fluorescence ◽  
Rate Equations ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
State Approximation ◽  
Three State Model ◽  
And Performance

The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental to providing insight into their stability and performance, which is not only relevant for organic light-emitting diodes (OLED), but also for other applications such as sensing, imaging and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing (ISC and RISC, respectively). In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.

scholarly journals A Unified Framework for Photophysical Rate Calculations in TADF Molecules

2021 ◽  
Author(s):  
Leonardo Evaristo de Sousa ◽  
Piotr de Silva
Keyword(s):  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Unified Framework ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Theoretical Approaches ◽  
Singlet States ◽  
Photophysical Behavior ◽  
Theoretical Standpoint

One of the challenges in organic light emitting diodes research is finding ways to increase device efficiency by making use of the triplet excitons that are inevitably generated in the process of electroluminescence. One way to do so is by thermally activated delayed fluorescence, a process in which singlet excitons undergo up-conversion to singlet states, allowing them to relax radiatively. The discovery of this phenomenon has ensued a quest for new materials that are able to effectively take advantage of this mechanism. From a theoretical standpoint, this requires the capacity to estimate the rates of the various processes involved in the photophysics of candidate molecules, such as intersystem crossing, reverse intersystem crossing, fluorescence and phosphorescence. Here we present a method that is able to, within a single framework, compute all these rates and predict the photophysics of new molecules. We apply the method to two TADF molecules and show that results compare favorably with other theoretical approaches and experimental results. Finally, we use a kinetic model to show how the calculated rates act in concert to produce different photophysical behavior.

scholarly journals Hot Exciplexes in U-Shaped TADF Molecules with Emission from Locally Excited States

2021 ◽  
Author(s):  
A. Lennart Schleper ◽  
Kenichi Goushi ◽  
Christoph Bannwarth ◽  
Bastian Haehnle ◽  
Philipp Welscher ◽  
...  
Keyword(s):  
Delayed Fluorescence ◽  
Organic Light Emitting Diodes ◽  
Intersystem Crossing ◽  
Thermally Activated Delayed Fluorescence ◽  
New Approach ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor And Acceptor ◽  
Low Efficiency ◽  
High Color Purity

Rapid reverse intersystem crossing and high color purity are vital characteristics of emitters with thermally activated delayed fluorescence in opto-electronic devices. We present a new approach, called “hot exciplexes” that enables access to both attributes at the same time. Hot exciplexes are produced by coupling facing donor and acceptor moieties to an anthracene bridge, yielding an exciplex with large T1 to T2 spacing. The hot exciplex model is investigated using optical spec-troscopy and quantum chemical simulations. Reverse intersystem crossing is found to occur preferentially from the T3 to the S1 state within only a few nanoseconds. Application and practi-cality of the model are shown by fabrication of organic light-emitting diodes with up to 32 % hot exciplex contribution and low efficiency roll-off.

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