4. Outlook and developments

These results show that modulating the electronic properties of 3π-2spiro compounds by modifying the nature of the different π systems is an interesting route to new blue-light emitters.

The use of intramolecular excimer emission as a light source in an OLED is still in its infancy, but could open up new perspectives in the future. The performance of the diodes presented here is still modest, and further optimization work should lead to improvements. A key point is the molecular design to be adopted, and particularly the rigidity of the molecular edifices. Indeed, the dimer must be "pre-formed" in the ground state to avoid conformational rearrangements in the excited state, which can lead to a significant drop in quantum yield and hence in OLED performance. Another key aspect of this work concerns the colors emitted by OLEDs. Indeed, OLEDs emit a deep blue with...