Compositionally Graded Organic–Inorganic Nanocomposites for Enhanced Thermoelectric Performance

Abstract Thermoelectric generators (TEGs) operate in the presence of a temperature gradient, where the constituent thermoelectric (TE) material converts heat into electricity via the Seebeck effect. However, TE materials are characterized by a thermoelectric figure of merit ( ZT ) and/or power factor (PF), which often has a strong dependence on temperature. Thus, a single TE material spanning a given temperature range is unlikely to have an optimal ZT or PF across the entire range, leading to inefficient TEG performance. Compositionally graded organic–inorganic nanocomposites are demonstrated, where the composition of the TE nanocomposite can be systematically tuned along the length of the TEG, in order to optimize the PF along the applied temperature gradient. The nanocomposite composition is dynamically tuned by an aerosol‐jet printing method with controlled in situ mixing capability, thus enabling the realization of such compositionally graded thermoelectric composites (CG‐TECs). It is shown how CG‐TECs can be realized by varying the loading weight percentage of Bi 2 Te 3 nanoparticles or Sb 2 Te 3 nanoflakes within an organic conducting matrix using bespoke solution‐processable inks. The enhanced energy harvesting capability of these CG‐TECs from low‐grade waste heat (<100 °C) is demonstrated, highlighting the improvement in output power over single‐component TEGs.