Intermolecular interactions enabled a semiconducting 2D supermolecular complex with robust humidity sensing performance

Abstract

As essential multifunctional materials, metal-organic complexes are attractive candidates showing superior sensing performance. However, the development of complex-based electronic sensors is still greatly limited by the low conductivity and unsatisfactory properties. Here, we report a new complex with formula of [Cd2(TAA)4(2,2′-bpy)2] (denoted as CdL, HTAA = 3-thiopheneacetic acid, 2,2′-bpy = 2,2′-bipyridine) synthesized via room-temperature precipitation. Hirshfeld surface analysis reveals the important effects of hydrogen bonds (54.6%) and Van der Waals interaction (31.5%) for constructing its 2D supermolecular structure. Favored by these intermolecular interactions, the semiconducting CdL exhibits high electronic conductivity at room temperature (1.71 × 10−5 S/cm). Consequently, the CdL powder was fabricated into a planar impedimetric device with high performance. Particularly, the CdL sensor exhibited high sensitivity (1.2 × 103), fast response (6 s), and small hysteresis (0.92%) in total relative humidity range of 33%−97%. In addition, complex impedance analysis was adopted to clarify the sensing mechanism of CdL. This contribution demonstrates the possible application of low-dimensional complexes in humidity sensors.