Luminescent Electrochromic Device Based on a Biohybrid Electrolyte Doped with a Mixture of Potassium Triflate and a Europium β-diketonate Complex

The “mixed cation” approach, which basically involves the use of two guest salts instead of a single one, is an attractive procedure that usually results in a significant increase of the ionic conductivity of polymer electrolytes (PEs). Recently, the sol-gel process [1] was successfully combined with the “mixed cation” effect to produce novel luminescent and ion conducting biohybrid electrolytes composed of a di-urethane cross-linked poly(e-caprolactone) (PCL(530)/siloxane hybrid network and a mixture of lithium and europium triflates, with application in electrochromic devices (ECDs) [2].

To enhance the quantum efficiency of these electrolytes, while preserving acceptable levels of ionic conductivity, we have decided in the present work to replace europium triflate by several europium b-diketonate complexes and to include other alkaline metal triflate salts [3,4]. In a previous study we concluded that adding lanthanide aquocomplexes incorporating b-diketonate ligands to d-PCL(530)/siloxane matrix is of interest as it yields an effective protecting cage that efficiently encapsulates the emitting centers and reduces luminescence quenching [5].

The structure, morphology and thermal stability of the new electrolyte systems have been characterized. ECDs have been built with optimized electrolyte samples and their performance has been analyzed by means of UV/VIS and chronoamperometric measurements.

[1] C. J. Brinker, G. W. Scherer, Sol-gel Science: The Physics and Chemistry of Sol-Gel Processing, Academic Press, San Diego, CA, 1990.

[2] M. Fernandes, S. S. Nobre, L. C. Rodrigues, A. Gonçalves, R. Rego, M. C. Oliveira, R. A. S. Ferreira, E. Fortunato, M. M. Silva, L. D. Carlos, V. de Zea Bermudez, ACS Appl. Mater. Interfaces, 3, 2011, 2953.

[3] S. C. Nunes, V. de Zea Bermudez, M. M. Silva, M. J. Smith, D. Ostrovskii, R. A. S. Ferreira, L. D. Carlos, J. Rocha, A. Gonçalves, E. Fortunato, J. Mater. Chem., 17, 2007, 4239.

[4] M. Fernandes, L. C. Rodrigues, R. A. S. Ferreira, A. Gonçalves, E. Fortunato, M. M. Silva, M. J. Smith, L. D. Carlos, V. de Zea Bermudez; Solid State Ionics, 204-205, 2011, 129.

[5] M. Fernandes, V. de Zea Bermudez, R. A. Sá Ferreira, L. D. Carlos, A. Charas, J. Morgado, M. M. Silva, M. J. Smith, Chem.Mater. 19, 2007, 3892.