OLED

OLEDs are very promising devices which efficiently convert electricity into light through the process of electroluminescence. They are made by depositing an active layer of a few tens or hundreds of nanometres thickness between two flat electrodes: one transparent electrode which is used as anode, and an electrode with a low work function used as cathode. Different classes of materials can be used as active layers, ranging from polymers to fluorescent or phosphorescent molecules. OLEDs, characterized by low embodied costs, are a very versatile type of technology having a wide range of applications.

Ir(III) cyclometalated complexes are attracting wide spread interest as emitters in OLEDs and light-electrochemical cells (LECs) because of their unique photophysical properties. The success of these complexes is related to their high stability, emission color tunability, and strong spin-orbit coupling, which sharply increases the efficiency of radiative transitions. OLEDs and LECs emitters should present sharp colors in the red, green, and blue region, exhibiting at the same time very high phosphorescence quantum yields.

\We have investigated by means of DFT/TDDFT cationic, neutral and anionic iridium complexes. The common aim of these investigations has been to individuate a relationship between the molecular structure of the Ir(III) complexes and their electronic, absorption and emission properties, thus aiding the design of new luminescent systems with improved characteristics.

References:

Baranoff, E.; Fantacci, S.; De Angelis, F.; Zhang, X.; Scopelliti, R.; Graetzel, M.; Nazeeruddin, M. K. Inorg. Chem. 2011, 50, 451–462.

Baranoff, E.; Bolink, H. J.; De Angelis, F.; Fantacci, S.; Di Censo, D.; Djellab, K.; Graetzel, M.; Nazeeruddin, M. K. Dalt. Trans. 2010, 39, 8914–8918.

Bolink, H. J.; De Angelis, F.; Baranoff, E.; Klein, C.; Fantacci, S.; Coronado, E.; Sessolo, M.; Kalyanasundaram, K.; Graetzel, M.; Nazeeruddin, M. K. Chem. Comm. 2009, 4672–4674.

Di Censo, D.; Fantacci, S.; De Angelis, F.; Klein, C.; Evans, N.; Kalyanasundaram, K.; Bolink, H. J.; Gratzel, M.; Nazeeruddin, M. K. Inorg. Chem. 2008, 47, 980–989.

De Angelis, F.; Santoro F.; Nazeeruddin, M. K.; Barone V J. Phys. Chem. B 2008, 112, 13181-13183.

De Angelis, F.; Fantacci, S.; Evans, N.; Klein, C.; Zakeeruddin, S. M.; Moser, J.-E.; Kalyanasundaram, K.; Bolink, H. J.; Gratzel, M.; Nazeeruddin, M. K. Inorg. Chem. 2007, 46, 5989–6001.

Nazeeruddin, M. K.; Wegh, R. T.; Zhou, Z.; Klein, C.; Wang, Q.; De Angelis, F.; Fantacci, S.; Gratzel, M. Inorg. Chem. 2006, 45, 9245–9250.