Organic luminescent radicals with blue-green emission for organic light-emitting diodes

Stable organic light emitting radicals are promising candidates for high-efficiency organic light emitting diodes (OLEDs). For radicals, both the ground state and the excited state are doublet states, thus, circumventing the non-radiative energy loss of the spin forbidden triplet state. The aim of this work was to synthesize new, stable, light-emitting organic radicals with emission in the visible range, which is ideally shifted towards the blue region of the spectrum in the solid state by utilizing aggregation induced emission (AIE) properties. The synthesis of these light-emitting radicals was achieved via two different synthetic pathways. In the first series of molecules, based upon an anthracene core structure, three precursors and two final radicals were obtained. For the second series, based upon a trityl core structure, also three precursors and two final products were synthesized, with tetraphenylethylene (TPE), mesitylene and pyrene being used as substituents. All of the final products displayed photoluminescent and paramagnetic properties. The radicals exhibit fluorescence emission in the range from 383 nm to 529 nm, with solid-state quantum yields of up to 16.5 %, showcasing the high potential of this approach to create new fluorophores for high-performance multicolored OLEDs in the near future.