To increase the current density of the hole only device, 1, 4, 5, 8, 9, 11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) material has been inserted in the device at the indium tin oxide (ITO)/organic interface. Since HATCN molecule can withdraw electrons, it can alter electronic properties of the electrodes and hence inserted between the organic/metal interfaces. This paper deals with the optimization of the thickness of organic-metal layers to enhance the efficiency. Also, efforts have been made to increase the current density and reduce the operating voltage of the device. The material 2, 7-bis [N, N-bis (4-methoxy-phenyl) amino]-9, 9-spirobifluorene (Meo-Spiro-TPD) is used to simulate the hole only device because it is a thermally stable hole transport material. Simulated results shows that better current density values can be achieved compared to fabricated one by optimizing the organic metal layer thickness. The best optimized layer thickness of 22 nm for Alq3, 25 nm for CBP* doped with Ir(ppy)3, 9 nm for Meo-Spiro TPD and 4 nm for HAT-CN which results in current density of 0.12 A/cm2 with a reduction in operating voltage by approximately 2 V.