Density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to analyse theoretically the optoelectronic, photophysical properties and organic light-emitting diode performance of a series of fac–mer blue-emitting Iridium (III) carbene complexes. Swain–Lupton constant is used to discuss the substituents effect. 5d-orbital splitting and d–d* transitions are calculated to assess the efficiency of the studied complexes. The reorganisation energies (λ), transfer integrals, mobilities, radiative decay rate (k_r), and triplet exciton generation fraction (χ_T) are also calculated. Due to the higher χ_T of these complexes, the formation of triplet exciton will be more and it will cause a faster intersystem crossing. Two host materials are proposed and host–guest match (Dexter–Förster energy) is also discussed. We hope that this unified work will surely help to design new blue-emitting phosphorescent materials in future.