Design of Efficient Yellow to Near-infrared Bis-cyclometalated Iridium(III) Phosphors via Ancillary Ligand Modification

Luminescent transition metal complexes, especially ones that contains iridium, have attracted considerable attention due to their unique photophysical properties and their applications in optoelectronic technology, photocatalysis, and phosphorescent probes in biological systems. Due to their continued development and implementation in applications, careful control and optimization of photophysical and electrochemical properties of these complexes are needed, motivating studies to understand structural-property relationships in order to design top performing molecular phosphors. While many iridium(III) complexes were designed, those emitting in the blue-green to yellow regions of the visible spectrum have already achieved near unity quantum yields. The luminescence quantum yields in the long wavelength regions (orange, red, and near-infrared) region tend to be intrinsically low for common structure types in this class. This dissertation is mainly focused on exploring ligand design strategies for new iridium(III) complexes. Chapter 1 introduces general photophysical principles of transition metal complexes with a brief overview of classes of cyclometalated iridium(III) complexes. In Chapters 2–4, various new designs of bis-cyclometalated iridium(III) complexes are presented and organized according to emission color ranging from green to yellow, red, and near-infrared regions with detailed studies of their electrochemistry and photophysical properties.