In this work, novel composite films that are composed of guest 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) and host polyvinylidene fluoride (PVDF) polymer are prepared. Results show that these guest-host composite films offer the advantages of strong second harmonic generation (SHG), scalability, flexibility, and long-term stability. The SHG pumped at 800 nm in the poled, thermally annealed, and phase-matched DAST−PVDF composite films are four orders of magnitude stronger than that of a pure PVDF film, or 300 times stronger than that of a potassium dihydrogen phosphate crystal. Particularly, the interface interactions of the electrostatic interactions and the strong intermolecular hydrogen bonds between DAST and PVDF improve the conjugation of π electrons and molecular ordering of DAST, making the NLO properties of the composites tunable with the ratio of DAST:PVDF. And consequently, the high SHG of the DAST−PVDF composite films can remain stable even after exposure to air for three years.

中文翻译：

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通过界面相互作用在柔性 DAST-PVDF 复合薄膜中产生长期稳定的强二次谐波

在这项工作中，新型复合膜，其是由客人的4- Ñ，N-二甲基氨基-4' -N制备了'-甲基-芪唑鎓甲苯磺酸盐（DAST）和主体聚偏二氟乙烯（PVDF）聚合物。结果表明，这些客-主复合薄膜具有强二次谐波（SHG）、可扩展性、灵活性和长期稳定性等优点。在极化、热退火和相位匹配的 DAST-PVDF 复合膜中，在 800 nm 处泵浦的 SHG 比纯 PVDF 膜强四个数量级，或比磷酸二氢钾晶体强 300 倍。特别是，静电相互作用的界面相互作用和 DAST 和 PVDF 之间的强分子间氢键改善了 π 电子的共轭和 DAST 的分子有序性，使得复合材料的 NLO 性能可以通过 DAST:PVDF 的比例进行调节。因此，