A theoretical investigation of heavy atom and oxidation effects in MR-TADF emitters for OLEDs: a combined DFT, double hybrid DFT, CCSD, and QM/MM approaches†

IF 2.9 3区 化学 Q3 CHEMISTRY, PHYSICAL
Singaravel Nathiya, Murugesan Panneerselvam and Luciano T. Costa
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引用次数: 0

Abstract

The emerging multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters with organoboron and nitrogen cores highlight their significance in OLEDs. However, their efficiency is challenged by slower rate constants in the reverse intersystem crossing (kRISC) process compared to conventional TADF emitters. The study entails an in-depth analysis focused on gaining a better understanding of the photophysical properties of MR-TADF emitters. Using DFT and TD-DFT analyses, 48 MR-TADF molecules are studied, incorporating heavy atoms such as sulfur and selenium, and their subsequent oxidation, and peripheral donors such as carbazole (Cz), tert-butyl-carbazole (tCz), diphenylacridine (DPAC), and dimethylacridine (DMAC) into organo boron and nitrogen-embedded systems. Moreover, the QM/MM approach was utilized to examine the excited state properties in the crystal phase. A comprehensive assessment of this molecular framework reveals that integrating heavy atoms and donors into MR-TADF molecules results in significant enhancements in ΔEST, larger SOC, and higher-order radiative (108 s−1) rates, leading to faster kISC (∼108 s−1) and kRISC (∼106 s−1) rates. Based on key criteria, eight potential molecules were selected and their excited-state properties were precisely analyzed using double-hybrid density functionals including B2PLYP and PBE0-2, along with highly correlated wave function STEOM-DLPNO-CCSD.

Abstract Image

Abstract Image

oled中MR-TADF发射体中重原子和氧化效应的理论研究:组合DFT、双混合DFT、CCSD和QM/MM方法
以有机硼和氮为核心的多共振热激活延迟荧光(MR-TADF)在oled中的应用具有重要意义。然而,与传统的TADF发射器相比,它们的效率受到反向系统间交叉(kRISC)过程中较慢的速率常数的挑战。该研究需要深入分析,重点是更好地了解MR-TADF发射器的光物理特性。利用DFT和TD-DFT分析,研究了48个MR-TADF分子,将硫和硒等重原子及其随后的氧化,以及咔唑(Cz)、叔丁基咔唑(tCz)、二苯基吖啶(DPAC)和二甲吖啶(DMAC)等外周给体纳入有机硼和氮嵌入系统。此外,利用QM/MM方法研究了晶体相的激发态特性。对该分子框架的综合评估表明,将重原子和供体整合到MR-TADF分子中可以显著增强ΔEST、更大的SOC和更高阶的辐射(108 s−1)速率,从而加快kISC (~ 108 s−1)和kRISC (~ 106 s−1)速率。基于关键标准,选择了8个势分子,并利用双杂化密度泛函B2PLYP和PBE0-2以及高度相关的波函数STEOM-DLPNO-CCSD对其激发态特性进行了精确分析。
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来源期刊
Physical Chemistry Chemical Physics
Physical Chemistry Chemical Physics 化学-物理:原子、分子和化学物理
CiteScore
5.50
自引率
9.10%
发文量
2675
审稿时长
2.0 months
期刊介绍: Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions. The journal has a broad scope and welcomes contributions spanning experiment, theory, computation and data science. Topical coverage includes spectroscopy, dynamics, kinetics, statistical mechanics, thermodynamics, electrochemistry, catalysis, surface science, quantum mechanics, quantum computing and machine learning. Interdisciplinary research areas such as polymers and soft matter, materials, nanoscience, energy, surfaces/interfaces, and biophysical chemistry are welcomed if they demonstrate significant innovation and/or insight into physical chemistry. Joined experimental/theoretical studies are particularly appreciated when complementary and based on up-to-date approaches.
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