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Formación, relajación y descomposición del excitón en el PCDTBT
Natalie Banerji1, Sarah Cowan, Mario Leclerc
1Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106-5090, USA.
Journal of the American Chemical Society
|November 20, 2010
Resumen
Los polímeros conjugados prístinos como el PCDTBT forman excitones en cuestión de picosegundos. Estos excitones migran y se relajan, un proceso mucho más lento que la transferencia de carga en las mezclas de PCDTBT: fullereno, lo que sugiere mecanismos alternativos para la separación de carga ultrarrápida.
Área de la Ciencia:
- La electrónica orgánica es la electrónica orgánica.
- Fotofísica de los polímeros conjugados.
Sus antecedentes:
- Los polímeros conjugados son materiales clave para la electrónica orgánica.
- Comprender la dinámica de la excitación primaria es crucial para la eficiencia del dispositivo.
Objetivo del estudio:
- Investigar la evolución temporal de las excitaciones en el PCDTBT prístino.
- Compara las dinámicas de relajación en películas delgadas y soluciones.
- Aclarar los mecanismos de la separación de cargas inducida por la luz.
Principales métodos:
- Espectroscopia de fluorescencia de conversión hacia arriba con resolución de femtosegundos.
- Medidas en películas delgadas y soluciones PCDTBT.
- Estudios sensibles a la polarización y dependientes de la longitud de onda.
Principales resultados:
- Fotogeneración de cargas móviles seguido de auto-localización dentro de 100 fs.
- Formación de excitones singlet enlazados en <1 ps.
- La migración de la excitación y la relajación conformacional ocurren durante 500 fs a decenas de picosegundos.
Conclusiones:
- La formación y migración de excitones en PCDTBT son más lentas que la transferencia de carga en las mezclas de PCDTBT: fullereno.
- Desafía el modelo de la difusión del excitón que precede a la separación de la carga.
- Propone mecanismos alternativos para la separación de carga ultrarrápida antes de la localización del excitón.
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