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Public defence in Inorganic Materials Chemistry, M. Sc. Sajida Kousar

Public defence from Aalto University School of Chemical Engineering, Department of Chemistry and Materials Science
Doctoral hat floating above a speaker's podium with a microphone

Title of the thesis: Exploring Co(Sb,Ge)(S,Se,Te) and CuCr(S,Se)₂ for enhanced thermoelectric performance

Doctoral researcher: M.Sc. Sajida Kousar 
Opponent: Dr. Emmanuel Guilmeau, CNRS Director of research, Laboratoire CRISMAT, France
Custos: Professori Maarit Karppinen, Aalto University School of Chemical Engineering

Optimizing thermoelectric materials for heat-to-power conversion: A study of CoSbS and CuCrS₂

In this thesis new thermoelectric materials for the conversion of heat into electricity are investigated. Development of such advanced materials is a crucial step toward sustainable energy solutions. Thermoelectric devices generate power directly from various waste heat without any byproducts or moving parts, and have great potential for applications ranging from mobile/wearable power sources to industrial waste heat recovery. However, current thermoelectric technologies often rely on rare or toxic elements, limiting their scalability and long-term use.

To address these challenges, two eco-friendly thermoelectric material systems, CoSbS and CuCrS2, composed of affordable and abundant elements were investigated. A significant finding was the unique bipolar nature of CoSbS, which simplifies the thermoelectric generator design and enhances its adaptability for various applications. Further optimization of CoSbS was achieved by incorporating a small amount of germanium, which improved electrical conductivity and reduced thermal conductivity—both crucial for improved thermoelectric efficiency. As a result, for CoSbS enhanced effectiveness in converting heat to electricity was demonstrated. For CuCrS₂, the thermal conductivity could be significantly reduced by substituting sulfur with selenium, thus making it better suited for efficient thermoelectric heat-to-power energy conversion.

These findings provide valuable insights into the future of thermoelectric technology, supporting the development of sustainable, cost-effective, and adaptable materials that can make waste heat recovery more practical and impactful. This research contributes to reducing reliance on fossil fuels and promotes a more sustainable energy landscape. 

 

Thesis available for public display 10 days prior to the defence

Contact information:
Sajida Kousar
[email protected]

Doctoral thesis in the School of Chemical Engineering

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