Correlating framework structures and thermoelectric performance of metal–organic framework/carbon nanotube thermoelectric hybrids with n–p type inversion

Abstract

Metal–organic frameworks (MOFs) show considerable promise as thermoelectric materials due to the inherently low thermal conductivities provided by their unique porous frameworks. Nevertheless, their applications are impeded by poor electrical conductivities and processabilities. Herein, novel n–p type carrier transport inversion MOF/carbon nanotube (CNT) thermoelectric hybrids are developed via controlled adjustment of the MOF/CNT composition. The low thermal conductivities of the MOFs provide optimized (zT) values of 0.071 and 0.025 for the n- and p-type thermoelectric hybrids, respectively. Moreover, a flexible thermoelectric generator consisting of seven p-n junction pairs in series provides a maximum open-circuit voltage of 11.2 mV and a maximum power of around 165.5 nW at a temperature difference of 20 K. This study introduces an alternative approach to creating high zT p- and n-type thermoelectric hybrids near room temperature by manipulating the composite ratio, and establishes a correlation between the framework structure and the thermoelectric performance, thereby supporting the development of MOF-based thermoelectric materials.