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Variaciones estadísticas excepcionalmente pequeñas en las propiedades de transporte de las uniones
Zuoti Xie, Ioan Bâldea1,2, Abel T Demissie
1Theoretical Chemistry, Heidelberg University , INF 229, D-69120 Heidelberg, Germany.
Journal of the American Chemical Society
|April 11, 2017
Resumen
Las uniones electrónicas moleculares con muchas moléculas paralelas muestran una alta reproducibilidad. Este estudio cuantifica las desviaciones en la resistencia, encontrándolas más pequeñas que las uniones de una sola molécula, allanando el camino para dispositivos moleculares robustos.
Área de la Ciencia:
- La electrónica molecular
- Nanotecnología
- Física de la materia condensada
Sus antecedentes:
- Las uniones de una sola molécula a menudo exhiben amplios histogramas de resistencia debido a fluctuaciones estocásticas.
- Esta variabilidad dificulta el desarrollo de dispositivos electrónicos moleculares confiables.
- Las mediciones de la temperatura ambiente son particularmente sensibles a estas fluctuaciones.
Objetivo del estudio:
- Investigar la reproducibilidad de las uniones moleculares con múltiples moléculas paralelas.
- Para analizar cuantitativamente las fuentes de desviaciones de resistencia en estas uniones.
- Para comparar el rendimiento de las uniones multimoleculares con las uniones monomoleculares.
Principales métodos:
- Fabricación de uniones moleculares mediante microscopía de fuerza atómica de sonda conductora (CP-AFM).
- Se utilizan moléculas de diitiol de oligofenileno (OPD) en monocapas autoensambladas (SAM) sobre el oro.
- Mecánica de contacto empleada, mediciones de cobertura superficial y un modelo de transporte analítico.
Principales resultados:
- Las uniones moleculares con aproximadamente 80 moléculas paralelas de dithiol de oligofenileno mostraron pequeñas desviaciones de resistencia relativa (δR / R ≈ 25%) después de ~ 200 mediciones.
- Se logró la determinación directa del número de moléculas (N) en la unión.
- Se identificaron las desviaciones en la energía orbital molecular (δε) y el acoplamiento molécula-electrodo (δΓ) como los principales contribuyentes a las variaciones de resistencia, no el número de moléculas (δN/N ≤ 2%).
Conclusiones:
- Las uniones compuestas por decenas de moléculas paralelas muestran una excelente reproducibilidad.
- Las desviaciones observadas son significativamente menores que las reportadas para las uniones de ruptura de una sola molécula.
- Estos hallazgos son cruciales para avanzar en el desarrollo de dispositivos electrónicos moleculares robustos y confiables.
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