The structural, photophysical and electrochemical properties of three luminescent 2-coordinate coinage metal (i.e., M = Cu, Ag, Au) complexes bearing a sterically bulky benzimidazolyl carbene, 1,3-bis(2,6-diisopropylphenyl)-1-H-benzo[d]imidazol-2-ylidene (BZI), and carbazolide (Cz) as the anionic ligand were investigated. All the complexes emit in the deep blue region (~430 nm) with relatively narrow spectra (full width at half maximum = 44 nm, 2,300 cm⁻¹) characterized by vibronic fine structure in nonpolar media (methylcyclohexane at room temperature), and with high photoluminescence quantum yields (Φ_PL > 80%) and radiative rate constants (k_r ~ 7.8 × 10⁵ s⁻¹). The luminescence is solvatochromic, undergoing a red-shift in a polar solvent (CH₂Cl₂) at room temperature that are accompanied by a decrease in quantum yields (Φ_PL < 23%) and radiative rate constants (k_r < 4.0 × 10⁴ s⁻¹), whereas the non-radiative rate constants remain nearly constant (k_nr ~ 1.0 × 10⁵ s⁻¹). The radiative rate is controlled via thermally assisted delayed fluorescence (TADF) and temperature-dependent luminescence studies of the gold complex (Au^BZI) in methylcyclohexane solution reveal an energy difference between the lowest singlet and triplet excited states of 920 cm⁻¹. An organic light-emitting diode (OLED) fabricated using Au^BZI as a luminescent dopant has an external quantum efficiency of 12% and narrow, deep-blue emission (CIE = 0.16, 0.06).