Hassan Abrar U, Sumrra Sajjad H
Department of Chemistry, University of Gujrat, PK, 54400, Gujrat, Pakistan.
J Fluoresc. 2022 Nov;32(6):1999-2014. doi: 10.1007/s10895-022-03003-3. Epub 2022 Jul 8.
The π-rich versus π-poor units in 4,6-di(thiophen-2-yl)pyrimidine (DTB) alternating the π-backbone of solar cells dyes have been extended with a push-pull technique to lower their HOMO-LUMO energy gap and to increase Intramolecular Charge Transfer (ICT). Density functional theory was used to optimize the ground state molecular geometries of newly designed dyes (DTB1-DTB6). Time Dependent DFT (TD-DFT) was used to simulate the Uv-vis spectral values at the maximum absorbance values ranging between 481-535 nm. These values were red shifted from DTB value of experimental (333 nm) and theoretical (346 nm). however, their computed absorbance and fluorescence spectra revealed a bathochromic shift of them upon an increasing the solvent polarity. Different DFT functionals such as (B3LYP, CAM-B3LYP, B97XD, and APFD) were employed to choose their proper use Uv-visible analysis to reveal an unexpected coherence at the B3LYP level with experimental values. As a result, the B3LYP with most diffused basis sets of 6-31G + (d,p) were used for further calculations. The parameters of Global Chemical reactivities revealed that all the dyes had a softer nature with their softness value range of 0.27-0.41. their Ionization Potentials (IP) ranged between 6.21-8.10 eV to comply that the new dyes had good electron donating potentials. With a good electron injection potential of -1.47-1.74 eV, aluminum can be the best electrode, while Au is excellent towards a hole injection operation which had the potential range of 1.79-3.68 eV. For Natural Bond Orbital (NBO) assessment, (N14)LP → (F16-F28)π* with stabilization energy of 42.55 kcal/mol was noted for DTB4. Their Second order hyperpolarizability [Formula: see text] values as their Nonlinear Optical (NLO) response ranged between 59.16-232.11 debye-angstrom which were almost 6 times higher than the reference DTB (8.47D). The NLO attributes has also shown that a dyes with its small bandgap was related with higher hyperpolarizability values. Because of the decreased reorganization frequencies, newly discovered derivatives with electron transfer qualities might be comparable to or equivalent to those of commonly used electron transmission materials.
采用推拉技术扩展了4,6 - 二（噻吩 - 2 - 基）嘧啶（DTB）中富π单元与贫π单元，以交替太阳能电池染料的π主链，从而降低其HOMO - LUMO能隙并增加分子内电荷转移（ICT）。利用密度泛函理论优化新设计染料（DTB1 - DTB6）的基态分子几何结构。使用含时密度泛函理论（TD - DFT）模拟最大吸收值在481 - 535 nm之间的紫外 - 可见光谱值。这些值相对于实验值（333 nm）和理论值（346 nm）的DTB值发生了红移。然而，它们计算得到的吸收光谱和荧光光谱显示，随着溶剂极性增加，光谱发生了红移。采用了不同的密度泛函（如B3LYP、CAM - B3LYP、B97XD和APFD）来选择适用于紫外 - 可见分析的泛函，结果发现在B3LYP水平下与实验值有意外的一致性。因此，使用具有6 - 31G + (d,p)最弥散基组的B3LYP进行进一步计算。全局化学反应性参数表明，所有染料性质较软，软度值范围为0.27 - 0.41。它们的电离势（IP）在6.21 - 8.10 eV之间，表明新染料具有良好的给电子势。铝具有 - 1.47 - 1.74 eV的良好电子注入势，可作为最佳电极，而金对于空穴注入操作非常出色，其势范围为1.79 - 3.68 eV。对于自然键轨道（NBO）评估，DTB4的（N14）LP → (F16 - F28)π*稳定化能为42.55 kcal/mol。它们的二阶超极化率[公式：见原文]值作为非线性光学（NLO）响应在59.16 - 232.11德拜 - 埃之间，几乎是参考DTB（8.47D）的6倍。NLO属性还表明，带隙小的染料与较高的超极化率值相关。由于重组频率降低，新发现的具有电子转移性质的衍生物可能与常用的电子传输材料相当或等同。
