Unipolar 1-phenylimidazo[1,5-a]pyridine: a new class of ultra-bright sky-blue emitters for solution-processed organic light emitting diodes

Abstract

Three fluorophores based on imidazo[1,5-a]pyridine (ImPy) decorated with an aromatic π-system (C3 position of ImPy is decorated with naphthalene, methoxy-naphthalene and pyrene) were designed and synthesized by the one-pot synthesis method. The fluorophores were structurally characterized, and detailed computational study reveals that the compounds showed wide energy gap (>3 eV). The presently studied fluorophores exhibited good thermal and electrochemical stability. The systematic photophysical study discloses that the compounds showed sky-blue emission with CIE color coordinates (x = 0.16/0.20, y = 0.22/0.32). ImPy derivatives were used as an emitter to fabricate a sky-blue emission OLED. The novel synthesized material demonstrates a good performance for sky-blue emission OLED. Among the three emitters, the highest performance was observed with ImPy-3 demonstrating the maximum EQE 4.3%, power efficiency 4.7 lm W⁻¹, and current efficiency 8.4 cd A⁻¹ at 100 cd m⁻².