The structure-property relationship study of a series of cationic Ir(III) complexes in the form of [Ir(C<^>N)(2)-(dtBubpy)]PF6 [where dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine and C<^>N = cyclometallating ligand bearing an electron-withdrawing group (EWG) at C-4 of the phenyl substituent, i.e., -CF3 (1), -OCF3 (2), -SCF3 (3), -SO2CF3 (4)] has been investigated. The physical and optoelectronic properties of the four complexes were comprehensively characterized, including by X-ray diffraction analysis. All the complexes exhibit quasireversible dtBubpy-based reductions from -1.29 to -1.34 V (vs SCE). The oxidation processes are likewise quasireversible (metal + C<^>N ligand) and are between 1.54 and 1.72 V (vs SCE). The relative oxidation potentials follow a general trend associated with the Hammett parameter (sigma) of the EWGs. Surprisingly, complex 4 bearing the strongest EWG does not adhere to the expected Hammett behavior and was found to exhibit red-shifted absorption and emission maxima. Nevertheless, the concept of introducing EWGs was found to be generally useful in blue-shifting the emission maxima of the complexes (lambda(em) = 484-545 nm) compared to that of the prototype complex [Ir(ppy)(2)(dtBubpy)]PF6 (where ppy = 2-phenylpyridinato) (lambda(em) = 591 nm). The complexes were found to be bright emitters in solution at room temperature (Phi PL = 45-66%) with microsecond excited-state lifetimes (te = 1.14-4.28 mu s). The photophysical properties along with density functional theory (DFT) calculations suggest that the emission of these complexes originates from mixed contributions from ligand-centered (LC) transitions and mixed metal-to-ligand and ligand-to-ligand charge transfer (LLCT/MLCT) transitions, depending on the EWG. In complexes 1, 3, and 4 the (LC)-L-3 character is prominent over the mixed (CT)-C-3 character, while in complex 2, the mixed (CT)-C-3 character is much more pronounced, as demonstrated by DFT calculations and the observed positive solvatochromism effect. Due to the quasireversible nature of the oxidation and reduction waves, fabrication of light-emitting electrochemical cells (LEECs) using these complexes as emitters was possible with the LEECs showing moderate efficiencies.