Previously adding carbon nanotubes (CNT) reduces the light emission from the composite, due to quenching of charge carriers at the nanotubes, which are generally metallic in nature for multi-walled CNT. This quenching reduces the emission efficiency of the devices.
This increase in light-emission only occurred when they acid treated the MWCNT prior to inclusion in the polymer. They propose that this increase is due to a novel energy transfer mechanism, from the acid-damaged surface of the MWCNT to the emitting sites in the polymer. In addition to the enhanced light-emission, the study also demonstrates that the MWCNT produced an improvement in the stability of the polymer to light-induced degradation.
Dr. Simon Henley, one of the lead investigators, comments "These results show that carbon nanotubes have enormous potential as a versatile material in future optoelectronic devices, and raise the prospect of utilising MWCNTs to harvest solar radiation in organic solar cells, in addition to improving device stability. "
Professor Ravi Silva, Director of the Advanced Technology Institute states: "The mere fact that now we can have a predictable organic-nanotube hybrid composite, with enhanced properties should open the door for many new applications. The enhancement in the luminescence properties bodes well a new generation of organic devices that could potentially reach commercially viable figures of merit for large scale production.