A high-efficiency green phosphorescent organic light emitting diode with a simplified structure is achieved that is free of a hole transport layer.The design of this kind of device structure not only saves the consumption of organic materials but also greatly reduces the structural heterogeneities and effectively facilitates the charge injection into the emissive layer.The resulting green phosphorescent organic light-emitting diodes(PHOLEDs)exhibit higher electroluminescent efficiency.The maximum external quantum efficiency and current efficiency reach 23.7% and 88cd/A,respectively.Moreover the device demonstrates satisfactory stability,keeping 23.7% and 88cd/A,22% and 82cd/A,respectively,at a luminance of 100 and 1000cd/m~2.The working mechanism for achieving high efficiency based on such a simple device structure is discussed correspondingly.The improved charge carrier injection and transport balance are proved to prominently contribute to achieve the high efficiency and great stability at high luminance in the green PHOLEDs. A high-efficiency green phosphorescent organic light emitting diode with a simplified structure is achieved that is free from a hole transport layer. The design of this kind of device structure not only saves the consumption of organic materials but also reduces the structural heterogeneities and effectively facilitates the charge injection into the emissive layer. The resulting green phosphorescent organic light-emitting diodes (PHOLEDs) exhibit higher electroluminescent efficiency. The maximum external quantum efficiency and current efficiency reach 23.7% and 88 cd / A, respectively. , keeping 23.7% and 88cd / A, 22% and 82cd / A, respectively, at a luminance of 100 and 1000cd / m ~ 2. The working mechanism for achieving high efficiency based on such a simple device structure correspondingly. charge carrier injection and transport balance are proved to prominently contribute to achieve the high efficiency and great stabilizer ity at high luminance in the green PHOLEDs.