Simple Donor–Acceptor Luminogen Based on an Azaindole Derivative as Solid-State Emitter for Organic Light-Emitting Devices

A new luminescent azaindole derivative has been designed and synthesized to be implemented in a light-emitting device. The molecular geometry and frontier orbital energy have been investigated by using density functional theory. This newly synthesized molecule emits strongly both in solution and solid state. The fluorescence emission in THF upon addition of an increasing amount of H 2 O has been measured also, displaying an increase of the fluorescence signal which is associated with an aggregation-induced emission phenomenon. Double-layer light-emitting devices including an active layer of the novel emissive material were successfully fabricated. The red-shift of the electroluminescence spectra with respect to the photoluminiscence emission was attributed to the presence of different types of complexes in the emissive material (EM) layer, which are preferentially formed between the nearest-neighbor hole–electron pairs of the electron injection and the EM layers (electroplex).