Yang Cui-Cui, Zheng Xue-Lian, Tian Wei Quan, Li Wei-Qi, Yang Ling
Chongqing Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Chongqing University, Huxi Campus, Chongqing 401331, P. R. China.
School of Physics, Harbin Institute of Technology, Harbin 150001, P. R. China.
Phys Chem Chem Phys. 2022 Mar 30;24(13):7713-7722. doi: 10.1039/d1cp00383f.
Novel carbon based "X-type" graphene nanoribbons (GNRs) with azulenes were designed for applications in nonlinear optics in the present work, and the second order nonlinear optical (NLO) properties of those X-type GNRs were predicted using the sum-over-states (SOS) model. The GNRs with edge states are feasibly polarized. The effects of zigzag edges on the NLO properties of GNRs are scrutinized by passivation, and the electronic structures of GNRs are modulated with heteroatoms at the zigzag edges for improved stability and NLO properties. Those nanomaterials were further functionalized with electron-donating and electron-withdrawing groups (NH/NO) to enhance the NLO responses, and the connection of those functional groups at the azulene ends play a determinant role in the enhancement of the NLO properties of those X-type nanoribbons, , the static first hyperpolarizability (〈〉) changes from -783.23 × 10 esu to -1421.98 × 10 esu. The mechanism of such an enhancement has been investigated. Through two-dimensional second order NLO spectra simulations, particularly besides the strong electro-optical Pockels effect and optical rectification responses, strong electronic sum frequency generations and difference frequency generations are observed in those GNRs. The strong second order NLO responses of those GNRs in the visible light region bring about potential applications of these carbon nanomaterials in nonlinear nanophotonic devices and biological nonlinear optics.
在本工作中，设计了带有薁的新型碳基“X型”石墨烯纳米带（GNRs）用于非线性光学应用，并使用态叠加（SOS）模型预测了这些X型GNRs的二阶非线性光学（NLO）性质。具有边缘态的GNRs可实现极化。通过钝化研究了锯齿形边缘对GNRs NLO性质的影响，并在锯齿形边缘用杂原子调节GNRs的电子结构以提高稳定性和NLO性质。这些纳米材料进一步用供电子和吸电子基团（NH/NO）进行功能化以增强NLO响应，并且这些功能基团在薁端的连接在增强这些X型纳米带的NLO性质中起决定性作用，静态第一超极化率（〈〉）从-783.23×10 esu变为-1421.98×10 esu。研究了这种增强的机制。通过二维二阶NLO光谱模拟，特别是除了强电光普克尔效应和光整流响应外，在这些GNRs中还观察到强电子和频产生与差频产生。这些GNRs在可见光区域的强二阶NLO响应使得这些碳纳米材料在非线性纳米光子器件和生物非线性光学中具有潜在应用。
