For the last few decades, organic light-emitting diodes (OLEDs) materials have acquired great attention because of their potential applications in display technology and other light sources. In particular, the organometallic complexes of N-heterocyclic carbenes have experienced explosive development as efficient phosphorescent emitters. Recently, the Pt and Ir carbenes complexes have gained significant attention in this regard because of their potentials as blue emitters. The interest in carbenes as ligands in organometallic complexes originates due to their higher σ-donor capability.  The increase in the σ-donor  ability enhance the inaccessibility of the triplet MC state from the triplet excited MLCT state and consequently slowers the nonradiative rate constants, resulting in higher quantum yields for using as an efficient triplet emitters. Using DFT and TDDFT methodologies, we are working on iridium N-heterocyclic carbene complexes to elucidate the effect of different substitutions on the emission color tuning and quantum efficiency to be used as OLEDs.