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Fisión de excitón de singlete activado en un polímero semiconductor

Andrew J Musser¹, Mohammed Al-Hashimi, Margherita Maiuri

¹Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom. am956@cam.ac.uk

Journal of the American Chemical Society

|July 26, 2013

Resumen

La fisión del excitón simple genera directamente dos excitones triples de un fotón. Este estudio revela que el proceso ocurre a partir del excitón 1Bu inicial en poli (tiilenovinile), no el excitón 2Ag, con implicaciones para la energía fotovoltaica orgánica.

Área de la Ciencia:

La fotofísica es la fotofísica.
Electrónica orgánica y electrónica orgánica.
Ciencia de los materiales Ciencia de los materiales.

Sus antecedentes:

La fisión por excitón singlet (SEF) es un proceso fotofísico con potencial para mejorar la energía fotovoltaica orgánica.
Comprender los mecanismos de SEF es crucial para optimizar el rendimiento del dispositivo.
Estudios previos se centraron principalmente en el SEF intermolecular en moléculas pequeñas.

Objetivo del estudio:

Para investigar el mecanismo de la fisión del excitón singlet en el poli (tiilenovileno) semiconductor.
Para determinar el estado de excitación desde el cual se origina la fisión.
Para explorar el comportamiento de los excitones triplet generados en solución versus películas sólidas.

Principales métodos:

Se empleó espectroscopia ultrarrápida (resolución inferior a 100 fs) para observar directamente el proceso de fisión.
Se llevaron a cabo estudios sobre el poli (tienenileno vinileno) tanto en estado de solución como en estado de película delgada.
Caracterización de la dinámica del excitón y de la formación de estados triplet.

Principales resultados:

Observación directa de la fisión del excitón singlete activado que ocurre en menos de 100 femtosegundos.
Demostración de que la fisión procede directamente de la excitación inicial de 1Bu, desafiando los modelos existentes.
En solución, los pares de tripletes se recombinan rápidamente a través del estado 2Ag; en películas, la difusión de excitones conduce a tripletes de larga vida y estados de transferencia de carga.

Conclusiones:

El estudio aclara una nueva vía para la fisión del excitón singlet iniciada por el excitón 1Bu.
La difusión del excitón en películas sólidas es fundamental para generar trillizos de larga vida y permitir la separación de cargas.
Los hallazgos proporcionan nuevos conocimientos para el diseño de materiales y dispositivos fotovoltaicos orgánicos eficientes.

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