## 1 Introduction
Memoelectric composites based on conductive polymers can be prepared via solution mixing, interfacial polymerization and in situ chemical oxidative polymerization [16; 17]. Physical (or mechanical) mixing was also reported to prepare PEDOT:PSS-Bi\({}_{2}\)Te\({}_{3}\) (PEDOT:PSS-ZT\({}_{\text{max}}\) = 1.0 \(\times\) 10\({}^{-2}\)), PANI-Bi\({}_{2}\)Te\({}_{3}\) (PANI: ZT\({}_{\text{max}}\) = 2.67 \(\times\) 10\({}^{-4}\)-1.1 \(\times\) 10\({}^{-2}\)) [18] and Acrylonitrile-Butadiene-Styrene (ABS)-Bi\({}_{x}\)Sb\({}_{2\times}\)Te\({}_{3}\)[19]. Although in those examples the recorded ZT values are very low, as already mentioned, such composites exhibit distinct advantages over all-inorganic thermoelectric materials, including high flexibility, low cost and easy processability. Consequently, new thermoelectric generator designs can be developed, including devices derived from screen printing, where the thermoelectric elements can be printed in 2D and then folded into shape as 3D thermoelectric devices with very high thermocouple density per unit area (e.g., 190 per cm\({}^{2}\)) [20]. Beyond this, a large variety of fabrication techniques that can be applicable in the development of organic-based thermoelectric devices already exists, including drop-casting and spin-coating [21], layer-by-layer deposition [22], electrospinning [23] and printing methods [20]. The thermoelectric performance of organic-based materials is strongly regulated by the processing parameters applied during synthesis, including pressure, temperature and processing time. For example, [PERSON] et al. [24] reported that, for PANI pellets prepared by compressing the corresponding polymer powder, only at pressures higher than 300 MPa could a reliable conductivity value be measured, while for lower pressures, pellets that were characterized by a lower apparent conductivity, density, Young's modulus and hardness were obtained. In another study, a higher drying temperature applied to PEDOT:PSS/CNT composites after synthesis resulted in enhanced polymer-CNT interfacial interactions and eventually improved thermoelectric performance [25]. Nevertheless, there seems to be a knowledge gap on the effect of different processing parameters employed during the formation of bulk organic-based composites, including temperature, pressure and processing time, and their further correlation to the materials' thermoelectric performance. Hence, by conducting systematic parametric studies with respect to the different processing parameters applied during the materials' fabrication, a better understanding of the processing-to-thermoelectric performance relationship can be realized [26]. Based on the above, the present study aims to investigate the thermoelectric properties of PANI (Polyaniline--emeraldine salt)-Bi\({}_{0.4}\)Sb\({}_{1.6}\)Te\({}_{3}\) (BST) composites, prepared via mechanical (physical) mixing of the corresponding powders. An in-depth parametric study was carried out, aiming to fill the existing knowledge gap on the thermoelectric behavior of organic-inorganic bulk composites prepared by physical mixing of the starting materials that are available in powder form. The physical mixing of powders and the formation of bulk samples via mechanical press is a very simple process that can be easily scaled up and adopted for processing a vast range of different polymer-inorganic powder systems. Therefore, the present study provides useful insights on the compatibility of the chosen materials, the feasibility of the selected processing method and the effect of various processing parameters on the thermoelectric performance of the resulting composites. PANI was chosen due to its relatively good electrical properties in comparison to other polymers, its tunability in terms of chemical composition and properties that can be realized via doping, ease of synthesis, commercial availability and good environmental stability [27].