Borges Itamar, Guimarães Roberta M P O, Monteiro-de-Castro Gabriel, Rosa Nathália M P, Nieman Reed, Lischka Hans, Aquino Adelia J A
Departamento de Química, Instituto Militar de Engenharia (IME), Rio de Janeiro, Brazil.
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, USA.
J Comput Chem. 2023 Dec 5;44(31):2424-2436. doi: 10.1002/jcc.27208. Epub 2023 Aug 28.
The alternant polycyclic aromatic hydrocarbon pyrene has photophysical properties that can be tuned with different donor and acceptor substituents. Recently, a D (donor)-Pyrene (bridge)-A (acceptor) system, DPA, with the electron donor N,N-dimethylaniline (DMA), and the electron acceptor trifluoromethylphenyl (TFM), was investigated by means of time-resolved spectroscopic measurements (J. Phys. Chem. Lett. 2021, 12, 2226-2231). DPA shows great promise for potential applications in organic electronic devices. In this work, we used the ab initio second-order algebraic diagrammatic construction method ADC(2) to investigate the excited-state properties of a series of analogous DPA systems, including the originally synthesized DPAs. The additionally investigated substituents were amino, fluorine, and methoxy as donors and nitrile and nitro groups as acceptors. The focus of this work was on characterizing the lowest excited singlet states regarding charge transfer (CT) and local excitation (LE) characters. For the DMA-pyrene-TFM system, the ADC(2) calculations show two initial electronic states relevant for interpreting the photodynamics. The bright S state is locally excited within the pyrene moiety, and an S state is localized ~0.5 eV above S and characterized as a donor to pyrene CT state. HOMO and LUMO energies were employed to assess the efficiency of the DPA compounds for organic photovoltaics (OPVs). HOMO-LUMO and optical gaps were used to estimate power conversion and light-harvesting efficiencies for practical applications in organic solar cells. Considering the systems using smaller D/A substituents, compounds with the strong acceptor NO substituent group show enhanced CT and promising properties for use in OPVs. Some of the other compounds with small substituents are also found to be competitive in this regard.
交替多环芳烃芘具有可通过不同供体和受体取代基进行调节的光物理性质。最近，通过时间分辨光谱测量研究了一种具有电子供体N，N - 二甲基苯胺（DMA）和电子受体三氟甲基苯基（TFM）的D（供体）-芘（桥）-A（受体）体系DPA（《物理化学快报》，2021年，12卷，2226 - 2231页）。DPA在有机电子器件的潜在应用中显示出巨大潜力。在这项工作中，我们使用从头算二阶代数图示构建方法ADC(2)来研究一系列类似DPA体系的激发态性质，包括最初合成的DPA。额外研究的取代基有作为供体的氨基、氟和甲氧基以及作为受体的腈基和硝基。这项工作的重点是表征关于电荷转移（CT）和局域激发（LE）特征的最低激发单重态。对于DMA - 芘 - TFM体系，ADC(2)计算显示出两个与解释光动力学相关的初始电子态。明亮的S态在芘部分内局域激发，并且一个S态位于S态上方约0.5 eV处且被表征为芘的供体 - CT态。使用最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能量来评估DPA化合物用于有机光伏（OPV）的效率。使用HOMO - LUMO和光学能隙来估计在有机太阳能电池实际应用中的功率转换和光捕获效率。考虑使用较小供体/受体取代基的体系，具有强受体NO取代基的化合物显示出增强的CT并且在OPV中具有有前景的性质。还发现一些具有小取代基的其他化合物在这方面也具有竞争力。
