Polaronic state of conducting oligomer as a new approach to design non-lieaner optical materials: A case study of oligofurans

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2024-01, Vol.304, p.123288, Article 123288
• Main Authors: Ejaz, Iqra, Ahsan, Faiza, Asif, Misbah, Ayub, Khurshid
• Format: Article
• Language: English
• Subjects: Density functional theory (DFT); Oligofurans (nFu); Polaron; Static and dynamic hyperpolarizabilities
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.123288

[Display omitted] •Polaron formation in oligofurans is presented as a new strategy to improve nonlinear optical response.•Spin density suggest that polaron are stabilized as the chain length increases.•Polaron formation significantly increases static and dynamic hyperpolarizabilities.•The highest hyperpolarizability values of 3.1 × 104 au is observed for 9Fu*. The geometric, electronic and nonlinear optical properties of neutral and polaron based oligofurans are studied comparatively. We have reported the role of polaron to trigger the nonlinear optical response of oligofurans (nFu). The polaron based oligomers show excellent opto-electronic properties. The effect of polaron on nFu* chains is measured by electronic properties i.e (ionization energy, electron affinity, band gap) and global reactivity descriptors like softness, hardness and chemical potential than their neutral counterpart. An interesting trends of reactivity descriptors have been observed. Lower band gaps (EH-L = 4.66 and 4.41 eV) are observed for polaronic systems as compared to their neutral counterpart. On the other hand, the TD-DFT study further demonstrated that, as the size of chain increases, the absorption maxima (λmax) also increases with significant reduction in excitation energies (ΔE). Furthermore, the nonlinear optical response is confirmed through the linear polarizability (αo), static first order hyperpolarizability (βo) and dynamic (frequency denepndent) hyperpolarizability. Electric filed induced second harmonic generation (EFISHG) and electro-optic pockle effect (EOPE) at 532 nm and 1064 nm, commonly used lasers frequencies have also been employed. Our results showed that the maximum hyperpolarizabilities are observed for polaron based 7Fu* and 9Fu* i.e 1.3 × 104, and 3.1 × 104 au. This study concluded that these polaron based organic polymers (nFu*) are useful as an efficient NLO material with vast applications in different fields.