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Correlaciones de excitación en la fisión singleta intramolecular

Samuel N Sanders¹, Elango Kumarasamy¹, Andrew B Pun¹

¹Department of Chemistry, Columbia University , New York, New York 10027, United States.

Journal of the American Chemical Society

|May 17, 2016

Resumen

Hemos sintetizado dimeros asimétricos de pentaceno y tetraceno que permiten una fisión de singleta intramolecular eficiente (iSF). La longitud del puente influye en la localización del excitón y las tasas de iSF, ofreciendo información sobre la dinámica de los pares triplet.

Área de la Ciencia:

Fotoquímica orgánica
Ciencias de los materiales
Dinámica de la excitación

Sus antecedentes:

La fisión de singlet intramolecular (iSF) es un proceso crucial para mejorar la eficiencia de las células solares.
Comprender la dinámica y las correlaciones de los excitones es clave para optimizar la iSF.

Objetivo del estudio:

Sintetizar y caracterizar los heterodímeros asimétricos pentaceno-tetraceno con longitudes de puente de conjugación variables.
Investigar la dinámica espacial de los excitones y la generación de pares triplet durante iSF.
Esclarecer el papel de las correlaciones de excitón y la longitud del puente en la eficiencia de iSF y la recombinación de tripletes.

Principales métodos:

Síntesis de heterodímeros asimétricos pentaceno-tetraceno con diferentes longitudes de puente conjugado.
Análisis espectroscópico para determinar las energías singlet y triplet.
Medidas fotofísicas con resolución de tiempo para estudiar la dinámica del excitón y la cinética de la recombinación.
Cálculos teóricos para apoyar las observaciones experimentales.

Principales resultados:

Se observó una iSF rápida y eficiente en los heterodímeros sintetizados.
El aumento de la longitud del puente condujo a la localización de singlet y a tasas de iSF más lentas en comparación con los dímeros simétricos.
Se resolvieron las cinéticas de recombinación de tripletes no equivalentes, descomponiéndose principalmente a través de procesos concertados.
Se identificaron y separaron las especies transitorias, incluidos los trillizos correlacionados y no correlacionados.
La recombinación de pares de trillizos fue rápida a pesar de los trillizos individuales localizados.

Conclusiones:

Los heterodímeros asimétricos proporcionan una plataforma sintonizable para el estudio de los mecanismos iSF.
La longitud del puente influye críticamente en la deslocalización de la excitación, la eficiencia de iSF y la formación de tripletes.
Estos sistemas permiten el aislamiento y el estudio de especies transitorias cruciales para iSF, ayudando en el diseño de materiales fotofísicos avanzados.

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