## 1 Introduction
The choice of Bi\({}_{0.4}\)Sb\({}_{1.6}\)Te\({}_{3}\) was based on its high ZT and good thermoelectric properties [28], as well as its use in thermoelectric devices with moderate heat sources [29]. Due to the higher charge carrier concentration of BST compared to PANI, it is expected that its incorporation within the PANI matrix will result in an increase in the material's electrical properties (i.e., electrical conductivity and Seebeck coefficient) compared to pristine PANI [30]. [PERSON] et al. [31] reported the fabrication of PANI-Bi\({}_{2}\)Te\({}_{3}\) nanocomposites based on Bi\({}_{2}\)Te\({}_{3}\) nanorods and polyaniline PANI nanoparticles (70 wt.% PANI-30 wt.% Bi\({}_{2}\)Te\({}_{3}\)). These nanocomposites, having a core-shell/cable-like morphology, were prepared via in situ polymerization and further compressed under a 2-ton pressure that was applied at room temperature, resulting in the formation of nanocomposite thermoelectric pellets. The latter demonstrated improved thermoelectric performance compared to the pure polymer, achieving a ZT of 4.3 \(\times\) 10\({}^{-3}\) at room temperature (with \(\kappa\) = 0.1096 W/mK, \(\sigma\) = 11.626 S/cm and S close to 38 uV/K), which is considered a high value for bulk polymer-based thermoelectric composites. In another study, 5 wt.% Bi\({}_{2}\)Te\({}_{3}\)-95 wt.% PANI composites were fabricated via chemical oxidative polymerization and further processed under pressure (5 tons) at room temperature, resulting in a relative increase in electrical conductivity [32]. In addition, recent reports appearing in the literature focus on the fabrication of PANI-based thermoelectric materials and generators, including the fabrication of acid-doped PANI and PANI-Bi\({}_{2}\)Te\({}_{3}\) nanocomposites, as well as PANI-based thermoelectric composites in which different types of carbon-based nanoadditives, including single-wall carbon nanotubes (SWCNTs), multi-wall carbon nanotubes (MWCNTs) and graphite oxide (GO), have been incorporated within this polymer to improve thermoelectric performance [33; 34]. Unfortunately, in most of the above-mentioned studies, the effect of the processing parameters (i.e., temperature and pressure) on the materials' thermoelectric performance was not systematically investigated. To the best of our knowledge, this is the first systematic study dealing with the fabrication (by means of mechanical mixing) and thermoelectric characterization of PANI-Bi\({}_{x}\)Sb\({}_{2.x}\)Te\({}_{3}\) nanocomposites. The selection of Bi\({}_{x}\)Sb\({}_{2.x}\)Te\({}_{3}\) instead of Bi\({}_{2}\)Te\({}_{3}\), which was previously explored as an additive in polymer-based thermoelectric composites, was based on its very good performance as a p-type inorganic thermoelectric material at ambient conditions [35], exhibiting high hole concentration and mobility [28]. Most importantly, in the present study, the effect of various experimental parameters, including processing pressure, temperature and time employed during the composite pellet formation, along with the effect of the inorganic additive content (ranging from 0 to 45 wt.%) on the materials' thermoelectric properties, was systematically investigated. Consequently, the implementation of such systematic investigations could be highly valuable in identifying the optimum experimental parameters that could eventually lead to the best thermoelectric performance in polymer-based thermoelectric composites.