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Oscilación de la conductancia en las uniones moleculares de los compuestos de la escalera de carbono

Tomofumi Tada¹, Daijiro Nozaki, Masakazu Kondo

¹Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 812-8581, Japan.

Journal of the American Chemical Society

|October 28, 2004

Resumen

Los alambres moleculares de poliáceno (PA ((n) DTs) y polifenantreno (PPh ((n) DTs) muestran propiedades de conductancia únicas. Los DT PA exhiben menor amortiguación de conductividad y son prometedores para los dispositivos electrónicos de tamaño nanométrico debido a sus pequeñas brechas HOMO-LUMO.

Área de la Ciencia:

* Ciencia de los materiales y nanotecnología.
* Química y Física Computacional.

Sus antecedentes:

* Los compuestos de la escalera de carbono como el poliaceno (PA) y el polifenantreno (PP) son cruciales para la electrónica molecular.
* Comprender su conductividad eléctrica es clave para diseñar dispositivos eficientes a nanoescala.

Objetivo del estudio:

* Para calcular y analizar las conductancias eléctricas de PA{n) DTs y PPh{n) DTs.
* Para investigar la dependencia de la longitud del cable y los fenómenos de oscilación de conductividad en estos cables moleculares.
* Para comparar el rendimiento de PA{n) DTs y PPh{n) DTs con otros oligómeros pi-conjugados.

Principales métodos:

* La formulación de Landauer combinada con la teoría funcional de densidad (DFT).
* Cálculo de la función Surface Green utilizando los parámetros de Slater-Koster.
* Análisis de la dependencia de la longitud del cable, las brechas HOMO-LUMO, la energía orbital y la población de electrones.

Principales resultados:

* Los PA ((n) DTs muestran un amortiguamiento de conductividad significativamente menor que los PPh ((n) DTs, atribuido a las brechas HOMO-LUMO más pequeñas.
* Oscilación de conductividad observada tanto en PA(n) DTs como en PPh(n) DTs para n < 7, relacionada con la energía orbital y la población de electrones.
* Conducción mejorada en PA{n) DTs con anillos pares y en PPh{n) DTs con anillos impares.
* Otros oligómeros pi-conjugados estudiados exhibieron una decadencia de conductividad exponencial ordinaria.

Conclusiones:

* Los PA (n) DTs se identifican como cables moleculares superiores para aplicaciones electrónicas en nanoescala.
* El estudio aclara los mecanismos detrás de la oscilación de la conductividad y la dependencia de la longitud en los compuestos de la escalera de carbono.
* Los hallazgos proporcionan información valiosa para el diseño racional de componentes electrónicos moleculares.

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