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Convergencia de bandas electrónicas para productos termoeléctricos a granel de alto rendimiento
Yanzhong Pei1, Xiaoya Shi, Aaron LaLonde
1Materials Science, California Institute of Technology, Pasadena, California 91125, USA.
Nature
|May 6, 2011
Resumen
Los investigadores mejoraron los materiales termoeléctricos para la recuperación del calor residual al aumentar la degeneración del valle en aleaciones a granel. Este avance logra una alta cifra de mérito (zT) de 1.8, allanando el camino para una conversión eficiente de calor a electricidad.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física del estado sólido Física del estado sólido
- Conversión de energía Conversión de energía.
Sus antecedentes:
- Los generadores termoeléctricos convierten el calor directamente en electricidad, con aplicaciones en la recuperación de calor residual.
- Los materiales termoeléctricos actuales tienen una eficiencia limitada (cifra de mérito, zT < 1,5), lo que dificulta su adopción generalizada.
- Se sabe que la degeneración de alto valle en bandas electrónicas mejora la eficiencia termoeléctrica.
Objetivo del estudio:
- Desarrollar nuevos materiales termoeléctricos con una cifra mejorada de mérito (zT) por encima de 1,5 para aplicaciones prácticas.
- Investigar métodos para aumentar la degeneración del valle en materiales termoeléctricos a granel.
- Demostrar una estrategia general para mejorar los materiales termoeléctricos a granel.
Principales métodos:
- Estructura de banda de ingeniería en aleaciones a granel de PbTe{1-x) Se{-x) mediante dopaje de afinación y composición.
- Se logró la convergencia de los valles de banda electrónica.
- Propiedades termoeléctricas medidas a temperaturas elevadas.
Principales resultados:
- Se ha demostrado una convergencia de al menos 12 valles electrónicos en aleaciones PbTe{1-x) Se{x) dopadas.
- Alcanzó una extraordinaria cifra de mérito termoeléctrico (zT) de 1,8 a aproximadamente 850 Kelvin.
- Mostró mejoras simultáneas en el coeficiente de Seebeck y la conductividad eléctrica.
Conclusiones:
- La ingeniería de bandas para converger bandas de valencia o de conducción es una estrategia viable para mejorar los materiales termoeléctricos a granel.
- La degeneración de alto valle alcanzada y el valor de zT representan un avance significativo en los materiales termoeléctricos.
- Este enfoque ofrece una vía general para descubrir y mejorar los materiales para la conversión eficiente de calor a electricidad.
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