White Luminescent Polymers by Plasma Polymerized Iridium Complexes from 1,10‐Phenanthroline

Abstract

A novel approach of fabricating white phosphorescent polymers for light‐emitting diodes (LEDs) was successfully developed via processes of plasma polymerization and complex chelation. Direct injection of high concentrations of aromatic monomer, 1,10‐phenanthroline (Ph), into plasma reaction chamber allowed the polymerization to take place in high yields with excellent retention of desired monomer functionalities. Constructed by conjugated segments of various lengths in their backbones, the synthesized polymer emitted broad‐band photoluminescence spectra from 380 to 600 nm. Subsequent refluxing with the transition metal iridium (Ir) resulted Ir–polymer complexes that manifested broad‐band fluorescence from 400 to 600 nm and phosphorescence from 450 to 700 nm. The phosphorescent emissions were assigned to a combination of triplet ligand‐centered π–π* and metal‐to‐ligand (ML) charge transfer emissions. Between electrodes, the polymer–Ir complexes emanated full‐spectral white‐light emissions that are composed of ligand‐centered π–π* emission with maxima at 435 nm and ML charge transfer emission with maxima at 605 nm. The devices exhibited voltage‐stable white luminescence with the Commission Internationale de l'Enclairage (CIE) coordinates of (0.25, 0.26), a maximum luminance efficiency of 7.44 cd · A−1, and a maximum luminance of 4 486 cd · m−2. This simple approach offers great potential for the synthesis and engineering of white organic LED phosphorescent materials.