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La modulación de la densidad de carga superficial inducida por ligandos genera una alineación de banda de tipo II

Rafael Quintero-Bermudez¹, Andrew H Proppe^1,2, Arup Mahata^3,4

¹Department of Electrical and Computer Engineering , University of Toronto , 10 King's College Road , Toronto , Ontario M5S 3G4 , Canada.

Journal of the American Chemical Society

|August 2, 2019

Resumen

La concentración de ligandos en las superficies de perovskita 2D controla la alineación de la banda, lo que permite interfaces sintonizables para la optoelectrónica. Este estudio explica cómo la variación de la densidad del ligando cambia la función de trabajo, induciendo la alineación de tipo II en materiales que de otro modo exhiben la alineación de tipo I.

Área de la Ciencia:

Ciencias de los materiales
Física de la materia condensada
Nanotecnología

Sus antecedentes:

Las perovskitas bidimensionales (2D) y cuasi 2D son cruciales para los dispositivos optoelectrónicos.
La alineación de la banda en estos materiales es controvertida, con informes contradictorios de interfaces de tipo I frente a tipo II.

Objetivo del estudio:

Investigar el papel de la concentración de ligando en la modulación de la alineación de bandas en perovskitas 2D.
Para conciliar los informes experimentales contradictorios sobre la alineación de la banda de perovskita.

Principales métodos:

Enfoques computacionales combinados (teoría funcional de la densidad) y experimentales (espectroscopia de fotoelectrones ultravioleta, absorción transitoria de la sonda de la bomba).
Modulación de la densidad superficial del ligando y su efecto sobre la función de trabajo y la transferencia de carga.

Principales resultados:

La concentración de ligando variable sintoniza la densidad de carga superficial y la función de trabajo efectiva de los pozos cuánticos.
La modulación de ligandos induce interfaces de tipo II en materiales con alineación intrínseca de tipo I.
Se han observado desplazamientos de la función de trabajo de hasta 1 eV; se ha confirmado experimentalmente una modulación de alineación de la banda de al menos 200 meV.

Conclusiones:

La concentración de ligandos es un factor clave que controla la alineación de la banda en las perovskitas 2D.
Este mecanismo explica los diversos tipos de interfaz (tipo I / tipo II) observados en los LED basados en perovskita y los fotovoltaicos.
Los hallazgos proporcionan una vía para la ingeniería de interfaces de perovskita para mejorar el rendimiento del dispositivo.

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