<p>Organic Light-Emitting Diodes make high-quality, low-cost colour displays possible, thereby ensuring high external quantum efficiency. This parameter affects the high light output and is related to the transparency and electrical conductivity of the electrodes. In turn, cathode transparency alters the OLED’s charge injection balance because the low thickness of the metal increases electrical conductivity. The engineering of thin metallic accounts for the balancing between the transparency of cathodes and their electrical conductivity. The obtained results connect the decreasing thickness of the metallic cathodes to produce transparent electrodes with the electrical performances of the OLED as defined by the common criteria such as current density, power efficiency and external quantum efficiency. The thickness of the metallic electrode is correlated with the mean free path of the electrons in each type of metal with direct implications in lowering the electrical conductivity. The production of OLED devices requires more precise control technology that significantly improves their functionalities, especially in terms of cathode transparency and electrical conductivity across the electroluminescent sandwich structures.</p>