This paper presents high-efficiency organic electrophosphorescent (PhOLED) devices using tris(2-phenylpyridine)iridium (Ir(ppy)₃) doped into various electron-transporting materials. The study demonstrates that Ir(ppy)₃ can achieve high internal quantum efficiency (η_int) approaching 100% due to the efficient utilization of both singlet and triplet excitons in electroluminescence. The devices were fabricated with an electron-transport layer (ETL) composed of BCP, OXD7, and TAZ as hosts, and an Al–Li cathode. The maximum external quantum efficiency (η_ext) achieved was 15.4 ± 0.2%, with a power efficiency of 40 ± 2 lm/W. The study also shows that the efficiency is significantly influenced by the ETL material and the cathode choice. The results indicate that the efficiency can be further improved by optimizing light out-coupling through the use of microcavities, shaped substrates, or index-matching media. The study also discusses the emission mechanisms, showing that exciton formation occurs within the EML, with minimal recombination in the adjacent Alq₃ layer. The paper concludes that the high efficiency of Ir(ppy)₃-based devices is due to the efficient energy transfer and the favorable triplet energy level alignment between the host and the dopant. The study also highlights the importance of the ETL in blocking hole and exciton transport, and the role of the cathode in electron injection. The results demonstrate that the use of an Al–Li cathode significantly enhances the η_ext compared to Mg–Ag. The study also shows that the efficiency of the devices is affected by the concentration of Ir(ppy)₃, with lower concentrations leading to a decrease in η_ext and additional blue host emission. The study concludes that the high efficiency of Ir(ppy)₃-based devices is due to the efficient utilization of both singlet and triplet excitons in electroluminescence, and that further improvements in efficiency can be achieved by optimizing light out-coupling.This paper presents high-efficiency organic electrophosphorescent (PhOLED) devices using tris(2-phenylpyridine)iridium (Ir(ppy)₃) doped into various electron-transporting materials. The study demonstrates that Ir(ppy)₃ can achieve high internal quantum efficiency (η_int) approaching 100% due to the efficient utilization of both singlet and triplet excitons in electroluminescence. The devices were fabricated with an electron-transport layer (ETL) composed of BCP, OXD7, and TAZ as hosts, and an Al–Li cathode. The maximum external quantum efficiency (η_ext) achieved was 15.4 ± 0.2%, with a power efficiency of 40 ± 2 lm/W. The study also shows that the efficiency is significantly influenced by the ETL material and the cathode choice. The results indicate that the efficiency can be further improved by optimizing light out-coupling through the use of microcavities, shaped substrates, or index-matching media. The study also discusses the emission mechanisms, showing that exciton formation occurs within the EML, with minimal recombination in the adjacent Alq₃ layer. The paper concludes that the high efficiency of Ir(ppy)₃-based devices is due to the efficient energy transfer and the favorable triplet energy level alignment between the host and the dopant. The study also highlights the importance of the ETL in blocking hole and exciton transport, and the role of the cathode in electron injection. The results demonstrate that the use of an Al–Li cathode significantly enhances the η_ext compared to Mg–Ag. The study also shows that the efficiency of the devices is affected by the concentration of Ir(ppy)₃, with lower concentrations leading to a decrease in η_ext and additional blue host emission. The study concludes that the high efficiency of Ir(ppy)₃-based devices is due to the efficient utilization of both singlet and triplet excitons in electroluminescence, and that further improvements in efficiency can be achieved by optimizing light out-coupling.