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Efectos impares en el transporte de carga a través de monocapas autoensambladas
Martin M Thuo1, William F Reus, Christian A Nijhuis
1Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Journal of the American Chemical Society
|February 18, 2011
Resumen
El transporte de carga a través de monocapas autoensambladas (SAM) muestra un "efecto impar" basado en la longitud de la cadena de metileno. Los SAM de alcanetiol pares exhiben una mayor densidad de corriente que los impares, revelando sensibilidad a la estructura molecular.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química de las superficies.
- La electrónica molecular es la electrónica molecular.
Sus antecedentes:
- Las monocapas autoensambladas (SAM) son cruciales para la electrónica molecular.
- Comprender el transporte de carga a través de SAM es clave para desarrollar nuevos dispositivos electrónicos.
- El "efecto impar" en el transporte de carga se ha observado, pero requiere técnicas de medición precisas.
Objetivo del estudio:
- Para investigar la influencia de la paridad de la cadena de metileno (par y impar) en el transporte de carga a través de SAMs de n-alkanetiol.
- Evaluar la utilidad de los electrodos eutecticos de galio e indio (EGaIn) para las mediciones de transporte de carga sensible.
- Para determinar si el efecto impar-par es estadísticamente significativo y explorar sus orígenes.
Principales métodos:
- Formación de SAMs de n-alcanetiolos en superficies de plata (Ag(TS)) rayadas con plantilla ultraplanas.
- Fabricación de uniones de metal / SAM / óxido / EGaIn utilizando electrodos superiores eutecticos de galio e indio (EGaIn).
- Medición de la densidad de corriente (J) a través de los SAM en función de la longitud de la cadena y la paridad.
- Análisis estadístico de los datos recopilados sobre las tarifas de transporte.
Principales resultados:
- Los electrodos EGaIn, que forman una fina capa de óxido, permiten microcontactos cónicos estables y altos rendimientos de unión.
- El efecto impar-par en el transporte de carga es estadísticamente discernible, con los alcanetiolos pares mostrando una mayor densidad de corriente que los impares.
- La diferencia en la densidad de corriente es estadísticamente significativa, pero las diferencias en la constante de desintegración de túnel (β) o el factor pre-exponencial (J(0) no lo son.
Conclusiones:
- El sistema de electrodos EGaIn/óxido es sensible a las sutiles diferencias estructurales en los SAM, lo que permite la observación del efecto par-parejo.
- El estudio confirma un efecto par e impar estadísticamente significativo en el transporte de carga a través de SAMs de n-alkanetiol.
- Si bien se observa el efecto, los orígenes moleculares precisos siguen siendo un tema para futuras investigaciones.
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