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Grandes cambios de energía de excitación por intercambio de superficie reversible en nanocristales 2D II-VI
Yang Zhou1, Fudong Wang1, William E Buhro1
1Department of Chemistry, Washington University , Saint Louis, Missouri 63130-4899, United States.
Journal of the American Chemical Society
|November 17, 2015
Resumen
La pasivación superficial de las nanoestructuras de selenuro de cadmio (CdSe) y sulfuro de cadmio (CdS) se puede cambiar de forma reversible entre los ligandos de aminas y los carboxilatos metálicos. Este intercambio de ligandos influye en las propiedades ópticas de los puntos cuánticos y los estados de tensión.
Área de la Ciencia:
- Ciencias de los materiales
- Nanotecnología
- Investigación de puntos cuánticos
Sus antecedentes:
- Los puntos cuánticos (QD) son nanocristales semiconductores con propiedades ópticas y electrónicas sintonizables.
- La pasivación superficial es crucial para estabilizar los QD y controlar su rendimiento.
- El intercambio de ligandos es una estrategia común para modificar la química y las propiedades de la superficie de QD.
Objetivo del estudio:
- Investigar el intercambio de ligandos reversible en las nanoestructuras de selenuro de cadmio (CdSe) y sulfuro de cadmio (CdS).
- Comprender el impacto de la pasivación del carboxilato metálico en las propiedades ópticas del QD y los estados de deformación.
- Explorar el potencial para ajustar el comportamiento de QD a través de la modificación controlada de la superficie.
Principales métodos:
- Reacción de cinturones cuánticos de CdSe pasivados por n-octilamina con carboxilatos de metales anhídridos (M ((oleato) 2), M = Cd, Zn.
- Caracterización de las nanoestructuras cuánticas intercambiadas por ligando mediante espectroscopia y análisis estructural.
- Inversión de la pasivación mediante la adición de ligandos de aminas de nuevo a los QD pasivados por carboxilato metálico.
Principales resultados:
- Se logró un intercambio rápido y reversible entre las aminas de tipo L y la pasivación de carboxilato metálico de tipo Z para CdSe y CdS QD.
- La pasivación del carboxilato metálico (M(oleato) 2 dio lugar a un desplazamiento reversible de los espectros de absorción y emisión a una energía más baja.
- El desplazamiento espectral más grande (140 meV) se observó para los cinturones cuánticos de CdSe pasivados con Cd (oleato) 2, atribuido a cambios en la tensión y el confinamiento.
- La adición de Cd (oleato) 2 aumentó el grosor efectivo de los QD en aproximadamente la mitad de una monocapa.
Conclusiones:
- El intercambio de ligandos reversible ofrece una ruta fácil para ajustar las propiedades ópticas de las nanoestructuras cuánticas de CdSe y CdS.
- La pasivación del carboxilato metálico tiene un impacto significativo en los estados de deformación QD y las dimensiones de confinamiento, lo que lleva a cambios espectrales.
- Este trabajo demuestra un método controlable para modificar la química de la superficie QD y el comportamiento optoelectrónico.
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