NEWCPLECS · New circular polarized light-emitting electrochemical cells.

New circular polarized light-emitting electrochemical cells.

Thin-film organic-based lighting devices has been one of the most relevant technological fields since the last 25 years. Light-emitting electrochemical cells (LECs) and organic light emitting diodes (OLEDs) are leading examples of this technology. While OLEDs show disadvantages, such as a complex architecture and need of a rigorous encapsulation, LECs are single-layer devices using air-stable electrodes. The complex fabrication of multi-layered architectures on non-conventional substrates and the lack of recycling protocols are important roadblocks for the final cost reduction in terms of commercialization. Thus, OLEDs are prohibitively expensive for many large-scale applications, while LECs are much more competitive from an economic/manufacturing point of view. The key feature making LECs more fit for a low-cost continuous fabrication in ambient conditions with respect to OLEDs is the presence of mobile ions in the active layer. The latter redistribute upon applying bias forming the electrochemical doping zones. In addition, the devices are fully compatible with metal-free electrodes, such as graphene or carbon nanotubes. Nevertheless, the state of the art for competitive LECs, have been achieved only in the yellow/orange region by using luminescent polymers like Super Yellow and ionic transition metal complexes (iTMC) like Ir(III) cyclometallated complexes. In particular, the group of Prof. Ruben Costa is a pioneer on the development of Cu(I) coordination/organometallic compounds as emitter for thin-film LECs, but they found a series of limitations that require to be overcome for their application in benchmark devices. Thus, one objective stablished for this project was to overcome the low stability of Cu-iTMC based LECs.

Data: CORDIS, © European Union