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Bi8 Se7: Interacciones de enlaces π deslocalizadas que mejoran la movilidad del portador y el rendimiento
Fei Jia1,2, Yong-Yi Liu1, Yi-Fan Zhang1
1Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Journal of the American Chemical Society
|June 24, 2020
Resumen
Los investigadores descubrieron que los enlaces π deslocalizados mejoran la conductividad eléctrica en los materiales termoeléctricos [Bi2] [Bi2Q3]. Este hallazgo allana el camino para el desarrollo de dispositivos eficientes de conversión de energía a temperatura ambiente.
Área de la Ciencia:
- Ciencias de los materiales
- Física del estado sólido
- Conversión de energía
Sus antecedentes:
- La conversión ambiental de energía térmica en eléctrica es crucial para alimentar la electrónica portátil.
- Los materiales termoeléctricos a temperatura ambiente son escasos, lo que limita las aplicaciones.
- La familia [Bi2][Bi2Q3] ofrece una plataforma para el desarrollo de materiales termoeléctricos rentables y menos tóxicos.
Objetivo del estudio:
- Investigar el mecanismo para mejorar la conductividad eléctrica entre capas (σ) en la familia [Bi2][Bi2Q3].
- Proponer un nuevo índice (F) para evaluar la fuerza del enlace π deslocalizado entre capas.
- Identificar y validar experimentalmente nuevos materiales termoeléctricos dentro de esta familia.
Principales métodos:
- Primeros cálculos de principios para analizar la estructura electrónica y el enlace.
- Desarrollo y aplicación de un índice empírico (F = Dp,p(Bi0)/Dp,p(Bi3+)) para cuantificar la fuerza de los enlaces π.
- Síntesis y caracterización de Bi8Se7 y Te/Sb codificado Bi5.6Sb2.4Se5Te2.
- Medición de las propiedades termoeléctricas, incluida la movilidad del portador (μH), la conductividad eléctrica (σ), el coeficiente de Seebeck y la cifra de mérito (ZT).
Principales resultados:
- Las interacciones del enlace π deslocalizadas aumentan significativamente la movilidad del portador entre capas (μH) y la conductividad eléctrica (σ).
- Un valor óptimo de F de 1 maximiza μH; Bi8Se7 con F = 1.06 muestra un aumento de μH (33.08 cm2/V s)) y σ.
- La codificación de Te/Sb en Bi5.6Sb2.4Se5Te2 mejora el coeficiente de Seebeck, logrando una ZT de ~0.7 a 425 K, con una ZT predicha de ~1.2.
- Los resultados experimentales confirman las predicciones teóricas para Bi8Se7 y los materiales codificados.
Conclusiones:
- Los enlaces π deslocalizados son clave para mejorar la conductividad entre capas en termoeléctricos [Bi2] [Bi2Q3].
- Bi8Se7 es un material de tipo n prometedor con propiedades termoeléctricas mejoradas cerca de la temperatura ambiente.
- La codificación Te/Sb optimiza aún más el rendimiento termoeléctrico, lo que sugiere un potencial para aplicaciones avanzadas de recolección de energía.
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