Acenaphthene-imidazole based red-to-NIR Emissive Homoleptic and Heteroleptic Ir(III) complexes for OLEDs: Combined experimental and theoretical approach

Abstract

A series of homoleptic and heteroleptic Iridium(III) complexes (Ir-1–Ir-4) bearing on acenaphthene-imidazole have been successfully designed and synthesized. The photophysical properties of these complexes were examined with appropriate spectroscopic methods. The results, in combination with theoretical calculations, led us to clearly assign various electronic transition states. All the complexes show remarkably intense red-to-near-infrared (NIR) emission in the range 600–800 nm with moderate quantum yield (0.10–0.17). Singlet and triplet energy levels were calculated by using TD-DFT (Time Dependent-Density functional theory) calculations. In addition, investigations have been performed to explore the optical, electronic, charge transport, and stability properties of Ir(III) complexes as charge transport and emissive materials for OLEDs (Organic light emitting diodes). Furthermore, all the complexes have promising luminescence and hole transporting performance towards OLED application. According to theoretical calculations, it is clearly indicating that the Ir-4 complex has more potential as an emitter for deep red to NIR-OLED applications.