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Efecto de la polarización electrónica en los parámetros de transporte de carga en los semiconductores orgánicos
Edward F Valeev1, Veaceslav Coropceanu, Demetrio A da Silva Filho
1School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA. edward.valeev@gatech.edu
Journal of the American Chemical Society
|July 27, 2006
Resumen
El transporte de carga en los materiales orgánicos se predice con inexactitud por los métodos estándar. Los efectos de polarización, a menudo ignorados, alteran significativamente las energías del sitio y transfieren integrales, incluso en simples cristales moleculares.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física del estado sólido Física del estado sólido
- Química computacional es la química computacional.
Sus antecedentes:
- Los estudios teóricos de transporte de carga en materiales orgánicos utilizan comúnmente el método de "división de energía en dímeros".
- Este método asume que los parámetros de transporte de los cálculos de monómero/dimero son transferibles a los sistemas extendidos.
Objetivo del estudio:
- Investigar el impacto de los efectos de polarización en los parámetros de transporte de carga en los materiales orgánicos.
- Evaluar la transferibilidad de los parámetros de los sistemas dimeros a los sistemas extendidos, teniendo en cuenta la polarización.
Principales métodos:
- Utilizó el método de "división de energía en dímeros" para investigaciones teóricas.
- Energías de sitio calculadas e integrales de transferencia para dímeros de etileno y pentaceno y sistemas extendidos.
- Analizó la influencia de la polarización electrónica, en particular las contribuciones electrostáticas.
Principales resultados:
- Fallo demostrado de la transferibilidad de parámetros de dímeros a sistemas extendidos debido a efectos de polarización.
- Se demostró que el descuido de la polarización conduce a valores y tendencias de transferencia de integrales incorrectos.
- Se observaron cambios significativos en las diferencias de energía del sitio entre los sistemas de dímeros y extendidos (por ejemplo, un aumento del 30% en las pilas de pentaceno).
Conclusiones:
- La polarización electrónica tiene un impacto significativo en los parámetros de transporte de carga en los cristales moleculares orgánicos.
- El método de "división de energía en dímeros" requiere una cuidadosa consideración de la polarización para predicciones precisas en sistemas extendidos.
- Las integrales de transferencia calculadas directamente utilizando orbitales de monómeros localizados muestran una mayor similitud entre los sistemas de dímeros y extendidos.
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