Terahertz Conductivity of Free-Standing 3D Covalent Organic Framework Membranes Fabricated via Triple-Layer-Dual Interfacial Approach.

Processable covalent organic framework membranes (COFM) are emerging as potential semiconducting materials for device applications. Nevertheless, the fabrication of crystalline and free-standing 3D COFMs is challenging. In this work, a unique time and solvent-efficient triple-layer-dual interfacial (TLDI) approach for the simultaneous synthesis of two 3D COFMs from a single system is developed. Besides, for the first time, the optical conductivity of these free-standing 3D COFMs is analyzed using terahertz (THz) spectroscopy in transmission mode. Interestingly, these membranes show excellent transmittance at THz frequencies with very high intrinsic THz conductivities. The evaluated scattering time and plasma frequency of the free carriers of the COFMs are highly promising for future applications in optoelectronic devices in THz frequencies.