•A very simplified HWOLED with P–F structure has been successfully developed.•The forward-viewing CE and PE are as high as 59.4 cd/A and PE of 58.4 lm/W, respectively.•A simple but effective way towards high-efficiency HWOLEDs has been demonstrated.•The origin of this high-efficiency device is explored comprehensively.A highly efficient hybrid white organic light-emitting diode based on a simple structure has been successfully fabricated and characterized. By systematically investigating the influence of the emissive layer thickness, electron transporting layer thickness, spacer and hole transporting layer, the forward-viewing current efficiency and power efficiency of the resulting device without any out-coupling schemes or n-doping strategies can be as high as 59.4 cd/A and 58.4 lm/W, respectively. Besides, a Commission International de l’Eclairage of (0.412, 0.393) and a color rendering index of 60 are obtained at the current density of 11 mA/cm2. Through the optimization and investigation, the origin of this unique device is explored comprehensively. Undoubtedly, such presented results will be beneficial to the design of both material and device architecture for ultra high-performance white organic light-emitting diodes.