Comprehensive Insights into Synthesis, Structural Features, and Thermoelectric Properties of High-Performance Inorganic Chalcogenide Nanomaterials for Conversion of Waste Heat to Electricity

Abstract

Thermoelectrics are energy harvesters that can directly convert waste heat into electrical energy and vice versa. Currently, thermoelectric (TE) devices display lower efficiency as the materials used for construction possess a very low figure of merit (ZT). Therefore, understanding the structural features of materials, finding new materials, and analyzing their chemistry and physics play a vital role in enhancing their energy conversion efficiency. Among the different classes of TE materials, some inorganic chalcogenides are perfect candidates for power generation as they possess excellent TE properties. The objective of this review is to provide insights into structural features and innovative methods to obtain enhanced thermoelectric properties of selected inorganic chalcogenides. The review covers recent advances in preparation methods, structural features, and thermoelectric properties of selected metal selenides (Bi2Se3, Ag2Se, SnSe, etc.) and metal tellurides (Bi2Te3, SnTe, PbTe, etc.). The review also discusses the critical parameters for designing and optimizing the TE materials to obtain the required electrical conductivity (σ), Seebeck coefficient (S), and thermal conductivity (k). In addition, promising mechanistic approaches to be adopted for enhancing the efficiency of TE materials such as doping, alloying, and nanostructuring are discussed in detail. Finally, a summary that describes advancements in the materials design is provided with a prospect for future applications from these materials in the development of energy harvesting technology.

Solution-Processed Inorganic Thermoelectric Materials: Opportunities and Challenges

“…Solution-based syntheses offer the possibility of producing nanoparticles (NPs) with carefully curated features compared to those produced by mechanical methods. Thermoelectric materials have been prepared using aqueous and solvothermal methods with low costs and high energy efficiencies. − Yet, these methods do not provide a high level of control over the particle properties. Among the solution methods, surfactant-assisted synthesis, also known as colloidal synthesis, has outperformed any other known method, producing inorganic NPs with precise compositions and morphologies; , therefore, it is the most promising method for precisely designing NP-based precursors.…”

Advances in Nanoparticle-Enhanced Thermoelectric Materials from Synthesis to Energy Harvesting: A Review

“…Furthermore, innovative computational modeling techniques have been employed to accurately forecast and enhance the performance of these materials. In light of the urgent energy and environmental difficulties that the world currently confronts, thermoelectric materials possess significant potential in effectively tackling these concerns . The incorporation of thermoelectric materials into expansive power generation systems and harnessing renewable energy sources can significantly contribute to the advancement of sustainable energy solutions.…”

All-Solution-Processed Polythiophene/Carbon Nanotube Nanocomposites Integrated on Biocompatible Silk Fibroin Substrates for Wearable Thermoelectric Generators

“…Generally, rare or toxic inorganic compounds (tellurium, selenium, lead, etc.) with excellent thermoelectric performance have been used to investigate thermoelectric materials. − However, inorganic materials have common characteristics that limit their utilization, such as scarce resources, rigid form factors for compatibility with uneven surfaces, and expensive fabrication processes. , Flexible thermoelectric devices based on inorganic materials were reported; however, the flexibility needs to be applied from support by either the flexible substrate or blending with the flexible component. − Conversely, organic thermoelectric materials can overcome the aforementioned limitations because of their unique advantages over inorganic thermoelectric materials, such as intrinsic mechanical flexibility, scalable/low-cost manufacturing, and lightweight. − Organic/polymeric thermoelectric devices can be a promising candidate for future wearable/flexible thermoelectric energy conversion technologies that can be used for low-grade waste heat harvesting because more than 60% of unutilized waste heat is generated at a temperature below 150 °C owing to energy conversion inefficiencies. − Molecular doping of conjugated polymers, such as polyanilines, polythiophenes, metallated polymers, and donor–acceptor polymers, is widely used to study the thermoelectric properties. − Poly­(3,4-ethylenedioxythiophene) (PEDOT), one of the most popular and high-performance thermoelectric polythiophene derivatives, and poly­(styrene sulfonic acid) (PSS), a counterion, have been commercially used for thermoelectric materials through various doping/dedoping processes. − …”