Thermoelectric Generator Using Camphorsulfonic Acid-Doped Copper Benzene-1,3,5-Tricarboxylate Metal–Organic Frameworks with Polyaniline Coating

Metal–organic frameworks (MOFs), which comprise metal cations and organic ligands connected by coordination bonds, exhibit exceptional porosity and tunable properties, making them promising materials for thermoelectric (TE) applications. However, most MOFs have low electrical conductivity owing to limited conjugation and poor orbital overlap between ligands and metal ions. To address this challenge, herein, we designed and evaluated MOF-based hybrids with customizable thermal and electrical properties. By integrating conjugated polymers with MOFs, high conductivity for TE generation can be achieved. Copper benzene-1,3,5-tricarboxylate (CuBTC) was selected because of its high Seebeck coefficient at near room temperature. First, to increase the low electrical conductivity of CuBTC, it was coated with highly conductive (360 S/cm) polyaniline (PANI) (CuBTC/PANI). Then, camphorsulfonic acid (CSA) was used to dope CuBTC/PANI and further enhance its conductivity. Consequently, CuBTC/PANI/CSA is 1000 times more conductive than pristine CuBTC. A TE generator using CuBTC/PANI/CSA exhibited excellent performance with an output power density of 23.8 mW/cm2 at a temperature difference of 40 K. This significant improvement in TE performance enables the utilization of MOF-based hybrids in advanced TE applications, particularly for wearable and flexible devices.