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Síntesis y dinámica de excitación de polímeros conjugados sensibilizados por tripletes

Rolf Andernach¹, Hendrik Utzat^1,2, Stoichko D Dimitrov¹

¹†Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.

Journal of the American Chemical Society

|July 23, 2015

Resumen

Los investigadores desarrollaron un nuevo polímero para una transferencia de energía eficiente, permitiendo mejores células solares sensibles a tripletes y capas de conversión ascendente. Este material facilita la sensibilización del excitón del polímero de singleta a tripleta para aplicaciones optoelectrónicas avanzadas.

Área de la Ciencia:

Ciencias de los materiales
La fotoquímica
Química de los polímeros

Sus antecedentes:

La conversión eficiente de excitones singlet a excitones triplet es crucial para los dispositivos optoelectrónicos avanzados.
Los materiales basados en politiofeno ofrecen plataformas prometedoras para la manipulación de excitones.
La incorporación de complejos de metales pesados puede facilitar el cruce entre sistemas para la generación de estados triplet.

Objetivo del estudio:

Para sintetizar un nuevo copolímero anfitrión-invitado basado en politiofeno con un complejo integrado de platino-porfirina (TTP-Pt).
Investigar la dinámica del excitón y el mecanismo de formación de excitones triplet en películas delgadas del material sintetizado.
Evaluar el potencial de este sistema para aplicaciones en células solares sensibilizadas por tripletes y capas de conversión ascendente.

Principales métodos:

Síntesis de un nuevo copolímero anfitrión-invitado a base de politiofeno que incorpora un complejo Pt-porfirina (TTP-Pt).
Caracterización de la dinámica del excitón utilizando espectroscopia de absorción transitoria (TAS) con resolución en el tiempo a través de múltiples escalas de tiempo.
Monitoreo directo de la transferencia de excitón tripleto desde el complejo Pt-porfirina a la columna vertebral del polímero.

Principales resultados:

Síntesis exitosa de un copolímero de politiofeno-TTP-Pt que permite una sensibilización eficiente del excitón del polímero de singleta a tripleta.
Se ha demostrado la transferencia de excitón desde la columna vertebral del polímero a la Pt-porfirina, seguida de un cruce intersistémico al estado triplet.
Se observó una transferencia del 60% de excitón triplet de la Pt-porfirina al polímero con una constante de tiempo de 1087 ps.

Conclusiones:

El nuevo copolímero facilita la sensibilización eficiente del excitón triplet y la transferencia hacia atrás, lo que sugiere un equilibrio entre los estados triplet del polímero y la porfirina.
La baja longitud de difusión de tripletes en la columna vertebral del polímero conduce a un aumento de la población local de tripletes y al potencial para una mayor aniquilación de tripletes.
Este diseño de material es muy prometedor para el desarrollo de células solares sensibles tripletas avanzadas y capas de conversión ascendente.

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