Conjugated and processable self-standing vinylene-linked covalent organic framework membranes (COFMs) are highly demanding for photonics and optoelectronics. In this work, we have fabricated the first cyclotriphosphazene (CTP) cored vinylene-linked self-standing COFM (CTP-PDAN). For comparison purposes, we have successfully fabricated the imine-linked congener (CTP-PDA). Leveraging the inherent nonlinear optical (NLO) response of the CTP core, both membranes were directly mounted to evaluate NLO parameters using the open-aperture (OA) Z-scan technique. Direct measurement of NLO responses on membranes is advantageous and free from solvent and scattering effects, making it a more practical approach compared to the conventional dispersion mode. The OA Z-scan transmission yields a reverse saturable absorption signature exhibiting a higher NLO absorption coefficient (β) of 58.37 cm/GW for CTP-PDAN, compared to that of the imine-linked CTP-PDA COFM (β = 8.5 cm/GW). These results can be correlated to the efficient conjugation through the vinylene linkage in CTP-PDAN compared to the imine linked congener.

中文翻译：

---

作为非线性光学材料的八极环三磷腈核自支撑共价有机框架膜：键合类型和材料形式的影响

共轭且可加工的自支撑亚乙烯基连接的共价有机骨架膜（COFM）对光子学和光电子学的要求很高。在这项工作中，我们制备了第一个以环三磷腈（CTP）为核心的亚乙烯基连接的自支撑COFM（CTP-PDAN）。为了进行比较，我们成功地制备了亚胺连接的同系物（CTP-PDA）。利用 CTP 核心固有的非线性光学 (NLO) 响应，直接安装两种膜，使用开孔 (OA) Z 扫描技术评估 NLO 参数。直接测量膜上的非线性光学响应是有利的，并且不受溶剂和散射效应的影响，使其成为与传统分散模式相比更实用的方法。 OA Z 扫描传输产生反向可饱和吸收特征，与亚胺连接的 CTP-PDA COFM 相比（β = 8.5 cm/GW），CTP-PDAN 的 NLO 吸收系数 (β) 更高，为 58.37 cm/GW ）。与亚胺连接的同系物相比，这些结果可以与 CTP-PDAN 中通过亚乙烯基键的有效缀合相关。