Kayi Hakan, Şen Emire, Özkılınç Özge
Computational Chemical Engineering Laboratory, Department of Chemical Engineering, Ankara University, Tandoğan, 06100, Ankara, Turkey.
Dipertmento Di Scienze Matematiche, Informatiche E Fisiche, Università Degli Studi Di Udine, Via Delle Scienze 206, 33100, Udine, Italy.
J Mol Model. 2024 May 22;30(6):179. doi: 10.1007/s00894-024-05985-2.
Due to the widely known positive contributions of the quinoxaline group in organic semiconductors, we conducted a fully computational study using quantum mechanical methods to investigate the effect of quinoxaline in the electron acceptor unit with the combination of different chalcogen atoms on the band gap of a series of donor-acceptor-donor type conjugated polymers. Using density functional theory, we mainly calculated the electronic band gap values of the structures containing four different chalcogen atoms (O, S, Se, and Te) in the electron donor and acceptor units. While chalcogendiazoloquinoxaline groups were used as the electron acceptor units, furan, thiophene, selenophene, and tellurophene were used as the donor units. Our theoretical results showed that the use of heavy chalcogen atoms in both donor and acceptor units resulted in a low band gap. Besides this, the effect of heavy chalcogen atoms used in the electron donor units is much more pronounced compared to the ones used in the acceptor units. More importantly, our findings proved that the inclusion of the chalcogendiazoloquinoxaline group instead of benzochalcogenadiazole as the acceptor unit significantly decreases the electronic band gap of the conjugated polymer. The lowest band gap was found to be 0.10 eV for the 4,9-di(tellurophen-2-yl)-[1,2,5]telluradiazolo[3,4-g]quinoxaline polymer.
Conformational analysis of the monomers and their corresponding oligomers was performed at the B3LYP/LANL2DZ level of theory. Then, long-range corrected hybrid functional LC-BLYP in a combination with the LANL2DZ basis set was utilized for the calculation of electronic properties and HOMO and LUMO energy gaps of monomers and oligomers through the reoptimization of the lowest energy conformers obtained from the B3LYP/LANL2DZ calculations in the previous step. All energy minimum structures were confirmed through vibrational frequency analysis at both calculation levels. The Gaussian 09 rev. D.01 software was used for all calculations, and GaussView 5.0.9 for visualizations.
由于喹喔啉基团在有机半导体中广为人知的积极贡献，我们采用量子力学方法进行了一项全面的计算研究，以探究喹喔啉在电子受体单元中与不同硫族原子结合时对一系列供体-受体-供体型共轭聚合物带隙的影响。利用密度泛函理论，我们主要计算了电子供体和受体单元中含有四种不同硫族原子（氧、硫、硒和碲）的结构的电子带隙值。当硫族二氮杂喹喔啉基团用作电子受体单元时，呋喃、噻吩、硒吩和碲吩用作供体单元。我们的理论结果表明，在供体和受体单元中使用重硫族原子会导致带隙降低。除此之外，与受体单元中使用的重硫族原子相比，供体单元中使用的重硫族原子的影响更为显著。更重要的是，我们的研究结果证明，用硫族二氮杂喹喔啉基团代替苯并硫族二氮唑作为受体单元会显著降低共轭聚合物的电子带隙。对于4,9-二（碲吩-2-基）-[1,2,5]碲二氮杂[3,4-g]喹喔啉聚合物，发现其最低带隙为0.10电子伏特。
在B3LYP/LANL2DZ理论水平上对单体及其相应的低聚物进行构象分析。然后，通过重新优化上一步从B3LYP/LANL2DZ计算中获得的最低能量构象，利用长程校正杂化泛函LC-BLYP与LANL2DZ基组相结合来计算单体和低聚物的电子性质以及HOMO和LUMO能隙。在两个计算水平上，通过振动频率分析确认所有能量最小结构。所有计算均使用高斯09修订版D.01软件，可视化则使用GaussView 5.0.9。
