Department of Chemistry, University of Agriculture, Faisalabad, 38000, Pakistan.
Chemistry Department, Faculty of Science, Taif University, Khurma, P.O. Box 11099, Taif , 21944, Saudi Arabia.
J Mol Model. 2021 Oct 10;27(11):316. doi: 10.1007/s00894-021-04922-x.
In this theoretical study, quantum chemical analysis of five novel non-fullerene donor molecules designed from recently reported highly efficient (11.5%) donor molecule P2TBR, containing non-fused ring central thiophene-benzene-thiophene core, 2-D benzodithiophene donors, and end capped 3-methylrhodanine acceptors, has been performed to evaluate the photovoltaic parameters and their application in organic solar cells. These donor molecules consist of centrally introduced acrylonitrile acceptors in between thiophene-benzene-thiophene core of P2TBR, namely M1. Compounds M2-M5 were designed from M1 containing ZOPTAN core, through peripheral acceptor group modification by 2-methylenemalononitrile (M2), methyl 2-cyanoacrylate (M3), 2-(5,6-difluoro-2-methylene-3-oxo-2,3-dihydroinden-1-ylidene) malononitrile (M4), and 2-(3-methyl-5-methylene-4-oxothiazolidin-2-ylidene) malononitrile (M5). DFT and TD-DFT simulations of all molecules including reference were carried out using MPW1PW91 functional in conjunction with 6-31G (d, p) basis set. Optoelectronic properties, exciton dynamics, electron density distribution pattern, and charge mobility were further analyzed by absorption spectra, TDM plots, frontier molecular orbitals (FMO) analysis, and calculation of reorganization energies, respectively. Results reveal that central addition and end capped modification of acceptors in designed molecules proved to be effective strategy to finely tune the electronic and optical characteristics. Amongst all designed molecules, M4 exhibited improved opto-electronic parameters such as highest maximum absorption (695 nm) in chloroform, least band gap (2.24 eV), lowest values of λ (0.0034 eV), and λ (0.0054 eV) and lowermost binding energy (0.46 eV), because of mutual effect of extended pi-conjugation and significant electron pulling nature of terminal acceptors. Moreover, higher dipole moment, lower values of hole reorganization energy, and improved V of designed molecules than reference (R) make them efficient donors to enhance PCE of photovoltaic materials.
在这项理论研究中，对五个新型非富勒烯供体分子进行了量子化学分析，这些分子是基于最近报道的高效（11.5%）供体分子 P2TBR 设计的，P2TBR 含有非稠合环的噻吩-苯-噻吩核心、2-D 苯并二噻吩供体和末端封端的 3-甲基硫代罗丹宁受体。这些供体分子在 P2TBR 的噻吩-苯-噻吩核心之间引入了中央丙烯腈受体，即 M1。通过在 M1 中引入 ZOPTAN 核心，用 2-亚甲基丙二腈（M2）、甲基 2-氰基丙烯酸酯（M3）、2-（5,6-二氟-2-亚甲基-3-氧代-2,3-二氢茚-1-亚基）丙二腈（M4）和 2-（3-甲基-5-亚甲基-4-氧代噻唑烷-2-亚基）丙二腈（M5）对周边受体基团进行修饰，设计出了化合物 M2-M5。采用 MPW1PW91 泛函与 6-31G（d，p）基组，对所有分子（包括参考分子）进行了 DFT 和 TD-DFT 模拟。通过吸收光谱、TDM 图、前沿分子轨道（FMO）分析和重组能计算，进一步分析了光电性质、激子动力学、电子密度分布模式和电荷迁移率。结果表明，在设计的分子中，中央受体的添加和末端封端修饰被证明是精细调节电子和光学特性的有效策略。在所设计的分子中，M4 表现出了改进的光电参数，例如在氯仿中的最大最大吸收（695nm）、最小带隙（2.24eV）、最低值λ（0.0034eV）和λ（0.0054eV）以及最低结合能（0.46eV），这是由于末端受体的扩展π共轭和显著的电子拉电子性质的相互作用所致。此外，设计分子的较高偶极矩、较低的空穴重组能值和改进的 V 值比参考分子（R）更高，这使它们成为提高光伏材料光电转换效率的有效供体。
