Sun Hejing
College of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao, China.
J Comput Chem. 2024 Dec 5;45(31):2612-2623. doi: 10.1002/jcc.27467. Epub 2024 Jul 23.
Development of organic nonlinear optical materials has become progressively more important due to their emerging applications in new-generation photonic devices. A novel series of chromophores based on innovative thiophene and furan-fused cyclopentadienyl bridge with various powerful donor and acceptor moieties were designed and theoretically investigated for applications in nonlinear optics. To unravel the structure-property relationship between this new push-pull conjugated systems and their nonlinear optical property, multiple methods, including density of states analysis, coupled perturbed Kohn-Sham (CPKS) method, sum-over-states (SOS) model, the two-level model (TSM), hyperpolarizability density analysis, and the (hyper)polarizability contribution decomposition, were performed to comprehensively investigated the nonlinear optical and electronic properties of this new π-system. Due to excellent charge transfer ability of new bridge and distinctive structure of donor and acceptor, the designed chromophores exhibit deep HOMO levels, low excitation energy, high dipole moment difference and large hyperpolarizability, indicating the appealing air-stable property and remarkable electrooptic performance of them. Importantly, THQ-CS-A3 and PA-CS-A3 shows outstanding NLO response properties with β value of 6953.9 × 10 and 5066.0 × 10 esu in AN, respectively. The influence of the push-pull strength, the heterocycle and the π-conjugation of new bridge on the nonlinear optical properties of this novel powerful systems are clarified. This new series of chromophores exhibit remarkable electro-optical Pockels and optical rectification effect. More interestingly, PA-CS-A3 and THQ-CS-A2 also show appealing SHG effect. This study will help people understand the nature of nonlinear optical properties of innovative heteroarene-fused based cyclopentadienyl chromophores and offer guidance for the rational design of chromophores with outstanding electrooptic (EO) performance in the future.
由于有机非线性光学材料在新一代光子器件中的新兴应用，其发展变得越来越重要。设计了一系列基于创新的噻吩和呋喃稠合环戊二烯基桥并带有各种强大供体和受体部分的新型发色团，并对其在非线性光学中的应用进行了理论研究。为了揭示这种新型推挽共轭体系与其非线性光学性质之间的结构 - 性质关系，采用了多种方法，包括态密度分析、耦合微扰Kohn - Sham（CPKS）方法、态叠加（SOS）模型、双能级模型（TSM）、超极化率密度分析以及（超）极化率贡献分解，以全面研究这种新型π体系的非线性光学和电子性质。由于新型桥具有出色的电荷转移能力以及供体和受体的独特结构，所设计的发色团表现出较深的最高占据分子轨道（HOMO）能级、低激发能、高偶极矩差和大超极化率，表明它们具有吸引人的空气稳定性和卓越的电光性能。重要的是，THQ - CS - A3和PA - CS - A3在乙腈中分别表现出出色的非线性光学响应特性，β值分别为6953.9×10和5066.0×10 esu。阐明了推挽强度、杂环以及新型桥的π共轭对这种新型强大体系非线性光学性质的影响。这一系列新型发色团表现出显著的电光普克尔效应和光学整流效应。更有趣的是，PA - CS - A3和THQ - CS - A2还表现出吸引人的二次谐波产生（SHG）效应。这项研究将有助于人们理解基于创新杂芳烃稠合环戊二烯基发色团的非线性光学性质的本质，并为未来合理设计具有卓越电光（EO）性能的发色团提供指导。
