## 1 Introduction  
Thermoelectric materials are used as a renewable source of energy because they can convert heat flow to electric power, utilizing waste heat or other heat energy sources [1, 2, 3]. Thermoelectric devices, which are typically made of n-type and p-type semiconductors [4], are employed in a wide range of applications such as long-term power generation in space and biomedical applications, industrial and automotive waste heat recovery, wearable sensors, temperature regulation in electronic devices, etc. [5]. Such devices present significant advantages, including the simple conversion of heat to electricity without using any moving parts and their long lifespan. However, conventional, all-inorganic thermoelectric devices have limited applications due to their high cost, rigid device designs and higher optimal working temperature [6]. As a consequence, the development of organic-based thermoelectric materials can alleviate the above-mentioned disadvantages with proper material choice, processing and design, derived from a better understanding of the selected preparation methodologies and corresponding parameters. Usually, materials are considered for thermoelectric applications based on their figure of merit \(ZT\)[7]:  
\[ZT=\frac{S^{2}\sigma}{\kappa}T \tag{1}\]  
where \(\sigma\) is the electrical conductivity, \(S\) is the Sebeck coefficient, \(\kappa\) is the thermal conductivity and \(T\) is the temperature in Kelvin. The term \(S^{2}\sigma\) is defined as the material's power factor, and it can be optimized via doping by incorporating high-mobility carriers to achieve higher electrical conductivity [8]. The main challenge in optimizing the performance of well-known thermoelectric materials and enhancing their efficiency stems from the fact that thermoelectric properties (i.e., Seebeck coefficient, electrical conductivity and thermal conductivity) are interdependent and have different dependencies on carrier density [9]. Bismuth Telluride thermoelectric materials ((Bi,Sb)\({}_{2}\)Te\({}_{3}\) or Bi\({}_{2}\)(Te,Se)\({}_{3}\)) are extensively used in devices due to their excellent thermoelectric properties at lower working temperatures [10]. However, these include rare and/or toxic elements such as Te, Se and Sb, thus making this selection environmentally unfriendly and costly [11]. Consequently, organic-inorganic polymer-based (nano)composites have attracted considerable attention as promising candidates for low-temperature applications [12], due to their low toxicity (and thus environmental friendliness), cost-effectiveness, flexibility and lightweight nature [13]. Apart from their intrinsically low thermal conductivity and low cost, polymer-based thermoelectric materials are also considered highly advantageous over inorganic-based materials due to their simple fabrication and facile processing. Furthermore, their chemical and physical properties can be easily tuned, thus rendering them highly flexible in terms of chemical composition and functionalization [14]. However, in comparison to inorganic thermoelectric materials like Bi\({}_{2}\)Te\({}_{3}\), organic thermoelectric materials are less efficient due to their significantly lower electrical conductivity and Seebeck coefficient. Hence, the combination of organic and inorganic thermoelectric materials can be a highly promising strategy in the development of innovative composites exhibiting enhanced thermoelectric performance. This is mainly due to the low thermal conductivity derived from the organic matrix and the high electrical conductivity and Seebeck coefficient attributed to the inorganic counterpart. Conductive polymers that are typically synthesized using oxidative chemical polymerization and are commonly used in thermoelectric applications include, among others, polyaniline (PANI), polypyrrole (PPy) and (poly(3,4-ethylenedioxythiophene) (PEDOT). Their ZT values typically range around 10\({}^{-3}\), but these can be significantly enhanced depending on the processing method and the incorporation of additives [15].