Deep Blue Fluorescent OLEDs Based on a Solution and Solid‐State Emitter (SSSE): Investigations with 2‐Phenyl‐Naphthoxazole

Abstract Blue fluorescent materials play a crucial role in the advancement of blue organic light‐emitting diodes (OLEDs) with high stability and high color purity. Fluorescent molecules known as Solution and Solid‐State Emitters (SSSEs) garner significant interest due to their unique optical properties. Most fluorophores exhibit strong emission in solution and typically lose their emissive properties in the solid state due to the emergence of intermolecular interactions in the aggregated phase. In contrast, SSSEs retain their fluorescence both in solution and in the solid state, making them highly valuable for various applications. This study focuses on 2‐phenyl‐naphth[2,3‐d]oxazole (Nzx) that exhibits SSSE‐like properties. This fluorescent molecule is characterized by deep blue emission near the UV range (300–450 nm). It is investigated with the goal of developing stable and high‐quality blue fluorescent OLEDs. To achieve this, Nzx is integrated as both an emissive layer and a dopant in OLED devices. The stability of the OLEDs under electrical stress is analyzed, and the device structure along with the doping concentration is investigated to optimize OLED performance. As a result, near deep blue‐emitting devices with an emission wavelength of 438 nm and an external quantum efficiency (EQE) of 1% are successfully achieved.