The design and synthesis of 1-phenylimidazo[1,5-a]pyridine – anthracene-based fluorophore for greenish-yellow organic light emitting diode and warm white LED

Abstract

Solution-processed OLEDs offer a promising and affordable technology for solid-state lighting and superior self-luminous display panels. Herein, an imidazo[1,5-a]pyridine (ImPy)-based fluorophore decorated with an aromatic π-system anthracene is synthesized by a one-pot condensation approach. From the theoretical study, the energy difference between HOMO and LUMO is 3.1 eV. The molecule shows excellent thermal stability and electrochemical stability. It exhibits efficient intramolecular charge transfer and displays a positive solvatochromic photoluminescence emission band ranging from 528 nm in hexane to 586 nm in acetonitrile with large Stokes’ shift of ∼11,000 cm−1. The OLEDs made of this emitter displayed good device performance with luminous efficiency of 4.4 cd A–1, power efficiency of 2.2 lm W–1 and external quantum efficiency of 3.2%. Additionally, this OLED emitted greenish-yellow light with CIE coordinate (0.34, 0.45) and possessed a low turn-on voltage of 7 V. The material also used in white LED fabrication and the fabricated white LED displayed an excellent color rendering index (CRI), the luminous efficiency of radiation (LER), and correlated color temperatures (CCT) of 89328 lm W–1 , and 4907 K, respectively with CIE coordinate (0.35,0.32).

Keywords

• Imidazo[1,5-a]pyridine
• Photoluminescence
• OLEDs
• LED
• Stokes’ shift