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Las pilas no paralelas de cromóforos donantes y receptores evaden la recombinación de carga geminada
Ajith R Mallia1, P S Salini1, Mahesh Hariharan1
1School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram , CET Campus, Sreekaryam, Thiruvananthapuram, Kerala, India 695016.
Journal of the American Chemical Society
|October 7, 2015
Resumen
Los investigadores desarrollaron una disposición apilada no paralela de pares de donantes y receptores para extender la vida útil de los estados de separación de cargas fotoinducidos. Esta nueva estructura reduce significativamente la recombinación de cargas, lo que lleva a estados excitados de mayor duración en la ciencia de los materiales.
Área de la Ciencia:
- Ciencias de los materiales
- La fotoquímica
- Química supramolecular
Sus antecedentes:
- Los pares donante-aceptante (DA) son cruciales para la separación de cargas en los procesos fotoquímicos.
- Lograr estados de carga separada de larga duración es esencial para aplicaciones como la conversión de energía solar y la electrónica molecular.
- El obstáculo estérico puede influir en la geometría molecular y el empaque, impactando las propiedades electrónicas.
Objetivo del estudio:
- Investigar una disposición apilada no paralela de pares de DA para prolongar los estados de separación de cargas fotoinducidos.
- Para entender el papel de la repulsión estérica en la determinación de la geometría molecular y el embalaje en estado sólido.
- Para correlacionar la disposición molecular con el tiempo de vida de los intermedios separados por carga.
Principales métodos:
- Síntesis de una diada de naftalina y naftalina (NIN).
- Caracterización de la geometría de la díada en soluciones y estados cristalinos.
- Espectroscopia de absorción transitorio de femtosegundos para monitorear los estados de carga separada.
Principales resultados:
- La repulsión estérica hidrógeno-hidrógeno en la díada NIN induce una geometría no plana.
- La geometría no plana facilita una disposición no paralela de pilas DA en el estado cristalino (grupo de espacio triclínico).
- La fotoexcitación conduce a la transferencia de electrones, formando pares de iones radicales con vidas significativamente más largas (> 1,2 ns) en el estado agregado en comparación con el estado monomérico (< 110 fs).
Conclusiones:
- Un arreglo de apilamiento DA no paralelo prolonga efectivamente la vida útil de los estados separados por carga fotoinducidos.
- Los efectos estéricos se pueden utilizar estratégicamente para controlar el empaque molecular y mejorar las propiedades fotofísicas.
- Este enfoque ofrece una vía para diseñar materiales avanzados con un mejor rendimiento en aplicaciones optoelectrónicas.
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