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La transferencia de energía hacia atrás de tripletes en polímeros conjugados con complejos de iridio fosforescentes
Nicholas R Evans1, Lekshmi Sudha Devi, Chris S K Mak
1Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Journal of the American Chemical Society
|May 18, 2006
Resumen
La adición de un cable de octametileno mejora significativamente la eficiencia de los diodos orgánicos electrofosforescentes emisores de luz. Este diseño suprime la transferencia de energía hacia atrás, mejorando el rendimiento en dispositivos con energías tripletas similares de huésped y huésped.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Electrónica orgánica y electrónica orgánica.
- La fotoquímica es la fotoquímica.
Sus antecedentes:
- Investigando la transferencia de energía del triplete de Dexter en diodos orgánicos electrofosforescentes emisores de luz (OLED).
- Utilizando complejos de iridio fosforescente emisores de rojo y polímeros conjugados de polifluoreno.
- Examinando el impacto de los enlaces directos (sin espaciador) frente a los enlaces atados en la transferencia de energía.
Objetivo del estudio:
- Para entender la influencia de la longitud del enlace en la transferencia de energía de tripletes en OLEDs.
- Optimizar el diseño de complejos de iridio fosforescente y copolímeros de polifluoreno para mejorar la eficiencia.
- Para aclarar el mecanismo de transferencia de energía y transferencia de vuelta en estos sistemas.
Principales métodos:
- Sintetizando monómeros de fluoreno sin espaciador y atados al octametileno funcionalizados con complejos de iridio.
- Extensión de la cadena a través de la policondensación de Suzuki para formar copolímeros estadísticos.
- Caracterización mediante análisis de rayos X, mediciones de foto y electroluminiscencia.
Principales resultados:
- Los monómeros sin espacio exhiben una conformación cara a cara cercana, lo que facilita la transferencia de energía intramolecular de tripletes.
- Los copolímeros atados al octametileno muestran el doble de eficiencia que sus contrapartes sin espaciador.
- El atado suprime con éxito la transferencia hacia atrás de los trillizos del complejo de iridio a la columna vertebral del polifluoreno.
Conclusiones:
- La incorporación de una cadena de octametileno es crucial para la alta eficiencia en los OLED con energías tripletas anfitrión-invitado similares.
- El diseño del enlace es un principio clave para optimizar la transferencia de energía y el rendimiento del dispositivo.
- La supresión de la transferencia triple hacia atrás es vital para una fosforescencia eficiente en los OLED.
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