Ren Shiwei, Habibi Amirhossein, Ni Pingping, Zhang Yuexing, Yassar Abderrahim
Zhuhai Fudan Innovation Institute of Fudan University, Guangdong-Macao in-Depth Cooperation Zone in Hengqin, Hengqin 518057, China.
Laboratory of Physics of Interfaces and Thin Films, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91128 Palaiseau, France.
Materials (Basel). 2023 Sep 26;16(19):6410. doi: 10.3390/ma16196410.
Many optoelectronic applications require organic semiconductor (OSC) materials with high electron affinity. In this work, a series of novel acceptor-donor-acceptor (A-D-A) materials with low-lying LUMO energy levels were designed and characterized. In this strategy, two acceptor dyes, bis-isatin and di-2-(2-oxindolin-3-ylidene) malononitrile, were connected by various π-bridges (benzene ring, benzo[c][1,2,5]thiadiazole, monothiophene, trithiophene). We varied the length of the π-conjugation of the central core and the linkage position of the acceptor core (4- vs. 6-position of the phenyl ring) to investigate the effect on the optical and electrochemical properties of the materials. We performed density functional theory (DFT) and time-dependent DFT (TD-DFT) studies to gain insight into the dyes' electronic properties by determining the energy levels. Our findings demonstrate that with increasing acceptor strength and π-conjugation length of the core, the wavelength of the longest absorption maximum as well as their respective extinction coefficients are enhanced, which results in band-gap reduction either by lowering the LUMO and/or raising the HOMO energy level of the molecules. The potential practical utility of these materials as electron-transport materials for perovskite solar cells (PSCs) has been demonstrated.
许多光电子应用需要具有高电子亲和力的有机半导体（OSC）材料。在这项工作中，设计并表征了一系列具有低LUMO能级的新型受体-供体-受体（A-D-A）材料。在该策略中，两种受体染料，双异吲哚酮和二-2-（2-氧代吲哚啉-3-亚基）丙二腈，通过各种π桥（苯环、苯并[c][1,2,5]噻二唑、单噻吩、三噻吩）连接。我们改变了中心核的π共轭长度和受体核的连接位置（苯环的4-位与6-位），以研究其对材料光学和电化学性质的影响。我们进行了密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）研究，通过确定能级来深入了解染料的电子性质。我们的研究结果表明，随着受体强度和核的π共轭长度增加，最长吸收峰的波长及其各自的消光系数均增大，这通过降低分子的LUMO和/或提高HOMO能级导致带隙减小。这些材料作为钙钛矿太阳能电池（PSC）的电子传输材料的潜在实际应用已得到证明。
