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Dependencia no exponencial de la conductividad en las uniones de túneles de oligotiofeno con terminación de yoduro
Limin Xiang1,2, Thomas Hines1, Julio L Palma1,2
1Center for Biosensors and Bioelectronics, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States.
Journal of the American Chemical Society
|December 24, 2015
Resumen
La conductividad molecular en los oligotiofenos se desvía sorprendentemente del decaimiento exponencial con la longitud. Este comportamiento no exponencial se atribuye a los cambios en la geometría de unión molecular a los electrodos, no solo a los túneles.
Área de la Ciencia:
- La electrónica molecular
- Física de la materia condensada
- Ciencias de los materiales
Sus antecedentes:
- La conductancia molecular típicamente disminuye exponencialmente con la longitud, lo que indica un túnel no resonante.
- Comprender la conductividad dependiente de la longitud es crucial para la electrónica molecular.
Objetivo del estudio:
- Investigar la conductividad molecular dependiente de la longitud de los oligotiofenos terminados en yoduro.
- Para aclarar el mecanismo de conducción subyacente responsable de las desviaciones observadas del decaimiento exponencial.
Principales métodos:
- Mediciones de conductividad a través de diferentes longitudes de moléculas de oligotiofeno.
- Espectroscopia de tensión de transición para sondear la barrera de túnel.
- Espectroscopia de fotoelectrones de rayos X y mediciones de longitud por estiramiento.
- Cálculos teóricos para modelar el comportamiento molecular.
Principales resultados:
- La conductividad del oligotiofeno mostró una disminución no exponencial con el aumento de la longitud molecular.
- La falta de dependencia de la temperatura confirmó el túnel como el mecanismo de conducción dominante.
- La espectroscopia de tensión de transición reveló una disminución dependiente de la longitud en la barrera de túnel.
- La espectroscopia de fotoelectrones de rayos X y los cálculos teóricos identificaron una transición en la geometría de enlace como la causa de la dependencia de longitud no exponencial.
Conclusiones:
- La geometría de unión de los oligotiofenos a los electrodos influye significativamente en la conductividad molecular.
- La dependencia de longitud no exponencial en las uniones moleculares puede surgir de cambios estructurales, no solo de efectos electrónicos.
- Este hallazgo proporciona nuevos conocimientos sobre el transporte de carga en sistemas moleculares.
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