In-Plane Oriented Two-Dimensional Conjugated Metal–Organic Framework Films for High-Performance Humidity Sensing
Sang-Wook Park, Zhe Zhang, Haoyuan Qi, Baokun Liang, Javeed Mahmood, Hyuk‐Jun Noh, Mike Hambsch, Mingchao Wang, Mao Wang, Khoa H. Ly, Zhiyong Wang, Inez M. Weidinger, Shengqiang Zhou, Jong‐Beom Baek, Ute Kaiser, Stefan C. B. Mannsfeld, Xinliang Feng, Renhao Dong⧫
Abstract
Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) have emerged as a new generation of conducting MOFs for electronics. However, controlled synthesis of thin-film samples with high crystallinity and defined layer orientation, which is beneficial for achieving high-performance devices and reliable structure–property relationship, has remained a challenge. Here, we develop a surfactant-directed two-step synthesis of layered 2D c-MOF films based on benzene and triphenylene ligands linked by copper-bis(diimino) complexes (HIB-Cu and HITP-Cu, respectively). The achieved layered 2D c-MOF films are featured as free-standing, in-plane oriented, and polycrystalline films with domain size up to ∼8000 nm2 and a tunable thickness in the range of 8–340 nm. Benefiting from the intrinsic electrical conductivity and quasi-one-dimensional pore channels, a HIB-Cu film based chemiresistive sensor is constructed, displaying effective humidity sensing with a response as fast as ∼21 s, superior to the reported MOF-powder-based chemiresistive sensors (in the orders of minutes).