Two-Dimensional Covalent Organic Framework Films for High Dielectric Strength Electrically and Thermo-Mechanically Stable Low Permittivity Dielectrics.

There is an urgent need to develop advanced dielectric materials with low permittivities (κ < 1.6) to address performance-limiting challenges for conventional and artificial intelligence (AI) microprocessors with miniaturized feature sizes, namely, delay in processing speeds, electronic crosstalk, high power consumption, and charge buildup. Known low-κ materials show poor dielectric strength and thermo-mechanical properties, rendering them unsuitable for next-generation electronic devices. Here, we demonstrate that the two-dimensional (2D) covalent organic frameworks (COF) films synthesized by the liquid-liquid interfacial reaction show very low permittivities (κ ≈ 1.17 at 100 kHz), ultrahigh dielectric strengths of ≈ 3908 MV/m at room temperature (≈2100 MV/m at 300 °C), low density of ≈1.1 g/cm3, and a high Young's modulus of ≈3.4 GPa. These properties are enabled by the highly crystalline and tightly packed nanoporous nanosheets of 2D COFs arranged in periodic structures in 2D COF films and surpass the requirements for next-generation electronic devices.