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Control de la rectificación en las uniones moleculares: efectos de contacto y firma molecular
Quyen van Nguyen1,2, Pascal Martin1, Denis Frath1
1Université Paris Diderot , Sorbonne Paris Cité, ITODYS, UMR 7086 CNRS, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France.
Journal of the American Chemical Society
|August 8, 2017
Resumen
Las uniones moleculares de estado sólido que utilizan capas finas de oligómeros muestran altas relaciones de rectificación. Las energías orbitales moleculares influyen significativamente en el flujo de corriente y el rendimiento del dispositivo.
Área de la Ciencia:
- La electrónica molecular
- Física del estado sólido
- Nanotecnología
Sus antecedentes:
- Las uniones moleculares son cruciales para el desarrollo de dispositivos electrónicos avanzados.
- Comprender el transporte de carga a través de capas moleculares es clave para controlar la funcionalidad del dispositivo.
Objetivo del estudio:
- Investigar el impacto de las energías orbitales moleculares en el transporte de carga en las uniones moleculares de estado sólido.
- Explorar las propiedades de rectificación de capas moleculares con características electrónicas variables.
- Elucidar los mecanismos que rigen el flujo de corriente y la rectificación en las uniones moleculares.
Principales métodos:
- Fabricación de uniones moleculares en estado sólido mediante reducción electroquímica de reactivos de diazonio para formar capas finas de oligómeros (7-9 nm) en electrodos de oro.
- Deposición de los contactos superiores Ti/Au para completar la estructura de unión molecular.
- Caracterización del rendimiento del dispositivo, incluidas las mediciones de corriente-voltaje (I-V), en un rango de temperaturas.
Principales resultados:
- Las capas moleculares basadas en oligo ((bistienilbenceno), con HOMO cercano al nivel de oro de Fermi, exhibieron altas relaciones de rectificación (> 1000) a 2,7 V.
- Los dispositivos con un alto contenido de moléculas HOMO-LUMO (tetrafluorobenzeno) no mostraron rectificación, mientras que las moléculas aceptadoras (dimidas de naftaleno) invirtieron la dirección de rectificación.
- Se observó que la rectificación persiste a bajas temperaturas (7 K) y no se activa entre 7 K y 100 K.
Conclusiones:
- La rectificación en las uniones moleculares está influenciada por los contactos asimétricos y las energías orbitales específicas de la capa molecular.
- Una "firma molecular" en el transporte de carga es evidente en capas más gruesas, distintas de los regímenes de túnel directo.
- Los hallazgos sugieren que la fijación a nivel de Fermi y el acoplamiento electrónico juegan un papel importante en el mecanismo de rectificación.
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