WOLED Race Heats Up

Two papers have recently been published on Iridium complexes incorporating acetylacetone and C-N based bidentate ligands. One paper is published in Chem Comm, by a European based group, the other is in Advance Materials by a collaboration out of China and Hong Kong.

The european group reports an octahedral compound (termed N966) with three ligands; 2 phenylimidazoles (coordinating to the Ir through a C and a N on the imidazole) and 1 acetylacetone. In solutions of DCM, at room temperature, it displays broad unstructured emission over the spectral range of 440nm – 800nm, centered around 570nm. It exhibits a PLQY (quantum yield) of 1.5% and radiative lifetime of almost 2μs. CV of the compound in DMSO exhibits reversible oxidation and reduction.
Bolink, H., De Angelis, F., Baranoff, E., Klein, C., Fantacci, S., Coronado, E., Sessolo, M., Kalyanasundaram, K., Grätzel, M., & Nazeeruddin, M. (2009). White-light phosphorescence emission from a single molecule: application to OLED Chemical Communications DOI: 10.1039/b908946b

The group in asia report of a polymer white LED (PWLED), created by doping blue light emitting iridium complexes with yellow iridium complexes, incorporating an electron-transporting material as well!

Wu, H., Zhou, G., Zou, J., Ho, C., Wong, W., Yang, W., Peng, J., & Cao, Y. (2009). Efficient Polymer White-Light-Emitting Devices for Solid-State Lighting Advanced Materials DOI: 10.1002/adma.200900638

These two papers illustrate the different approaches to the WOLEY grail I prefer the purer approach as I think it will ultimately result in a higher quality of fabricated devices, but I also appreciate that this approach will require a lot of trial and error….which is why I’m glad I’m not doing the research!