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High Power Factor Nb-Doped TiO2 Thermoelectric Thick Films: Toward Atomic Scale Defect Engineering of
Xiaodong Liu1, Demie Kepaptsoglou2,3, Ewa Jakubczyk4
1Department of Materials, University of Manchester, ManchesterM13 9PL, U.K.
ACS Applied Materials & Interfaces
|January 19, 2023
Summary
High-performance niobium-doped titanium dioxide (TiO2) thick films were fabricated using screen-printing. These materials exhibit enhanced thermoelectric properties due to engineered crystallographic shear structures, offering a promising route for efficient energy conversion.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Titanium dioxide (TiO2)-based materials are cost-effective and stable thermoelectric (TE) materials for high-temperature applications.
- Enhancing the thermoelectric performance of TiO2 requires advanced material engineering strategies.
Purpose of the Study:
- To fabricate high-performance niobium (Nb)-doped TiO2 thick films using scalable screen-printing techniques.
- To investigate the correlation between crystallographic shear (CS) structures and enhanced TE properties.
- To reveal the nano-scale nature of novel defect structures in Nb-doped TiO2.
Main Methods:
- Screen-printing of Nb-doped TiO2 thick films.
- Microstructure characterization using aberration-corrected scanning transmission electron microscopy (STEM).
- Analysis of crystallographic shear (CS) structures and defect engineering.
Main Results:
- Formation of high-density {121} and {210} CS structures in Nb-doped TiO2 films.
- Identification of a novel Al-segregated {210} CS structure in films with higher Nb content under reducing atmospheres.
- Observation of abundant oxygen vacancies within CS structures, facilitating energy-filtering effects.
- Achieved a maximum power factor of 4.3 × 10^-4 W m^-1 K^-2 at 673 K, the highest for TiO2-based TE films at elevated temperatures.
Conclusions:
- Engineered crystallographic shear structures, particularly the novel Al-segregated {210} CS structure, significantly enhance the thermoelectric performance of Nb-doped TiO2.
- Atomic-level defect engineering via microstructure modification provides a viable strategy for developing advanced thermoelectric materials.
- The findings pave the way for improved TiO2-based thermoelectrics for high-temperature energy conversion applications.
