Lefko-Phos · Binuclear Iridium(III) Complexes for White-Emitting OLEDs

The European Union set the ambitious target of increasing energy efficiency by 27% within 2030. Since ≈ 20% of the EU electrical energy is used for lighting, more efficient lighting concepts need to be developed. At present, inorganic light emitting diodes (LEDs) stand out as the best alternative to conventional lighting devices. In future, organic LEDs (OLEDs) are predicted to become the ultimate solution, since they allow fabrication of large-area flat and flexible devices; consequently, white-emitting OLEDs (WOLEDs) are actively investigated. Current WOLEDs require the use of multiple luminophores in a single device, but this leads to imbalanced white-light emission and colour instability, due to the different stability over time of each single emitter. Moreover, the incorporation of multiple emitters increases manufacturing costs. To overcome these drawbacks, attempts have been made to generate white-emission from a single multifunctional material. However, strong limitations were faced due to the complex synthetic procedures and the inability to control the excited-state properties of the emitter and its internal energy-transfer processes. In this scenario, we propose a new strategy for easy-to-synthesize binuclear cyclometalated iridium(III) complexes, displaying dual-emission for white-light generation from a single molecular entity. The strategy involves simultaneous generation of blue and orange emission from two electronically uncoupled Ir(III) centres, linked together by a non-conjugated bridging unit. This ambitious goal can be achieved due to the mutual interaction between the Experienced Researcher (ER) and the Host Institution (HI). While the ER has a strong background in the synthesis of luminescent complexes, the HI has a consolidated expertise in organic synthesis, theoretical and experimental photophysics, and in fabrication and testing of OLED devices. This combination of competencies will guarantee the successful implementation of this project.