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Separación de cargas de ruptura de simetría en estado sólido: Películas policristalinas de tetra (fenoxi)

Carolyn E Ramirez^1,2, Su Chen^2,3, Natalia E Powers-Riggs^2,3

¹Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208-3113, United States.

Journal of the American Chemical Society

|October 6, 2020

Resumen

La separación de carga de ruptura de simetría (SB-CS) en la energía fotovoltaica orgánica aumenta el voltaje. Las películas de H-tpPDI muestran casi SB-CS cuantitativo, superando al octyl-tpPDI y ofreciendo una promesa para las células solares orgánicas eficientes.

Área de la Ciencia:

Ciencias de los materiales
Las instalaciones fotovoltaicas
Productos electrónicos orgánicos

Sus antecedentes:

La generación de pares de electrones-agujero a través de la separación de carga de ruptura de simetría (SB-CS) es clave para aumentar la tensión de circuito abierto de energía fotovoltaica orgánica (OPV).
Los estudios anteriores se centraron principalmente en dímeros moleculares en solución, lo que limita la aplicabilidad a dispositivos de estado sólido.

Objetivo del estudio:

Investigar el SB-CS en películas delgadas policristalinas de 1,6,7,12-tetra-perileno-3,4:9,10-dicarboximida (tpPDI).
Comparar la eficiencia SB-CS entre películas con grupos n-octilo (octilo-tpPDI) y átomos de hidrógeno (H-tpPDI) en átomos de nitrógeno imida.

Principales métodos:

Fabricación en película delgada de octil-tpPDI y H-tpPDI.
Difracción y dispersión de rayos X para el análisis estructural.
Espectroscopia de absorción transitoria para sondear la dinámica del estado excitado.

Principales resultados:

Tanto las películas octil-tpPDI como las H-tpPDI presentan apilamiento π-π.
El H-tpPDI muestra más arreglos apilados y enlaces de hidrógeno intermoleculares en comparación con el octil-tpPDI.
Octyl-tpPDI muestra estados mixtos de singlet excitado y transferencia de carga (como excimer).
H-tpPDI demuestra casi cuantitativamente el SB-CS.

Conclusiones:

El empaque molecular y las interacciones intermoleculares influyen significativamente en la eficiencia de SB-CS en las películas tpPDI.
La estructura del H-tpPDI facilita la eficiencia del SB-CS, lo que lo convierte en un material prometedor para aplicaciones fotovoltaicas orgánicas avanzadas.

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