Abstract
A highly efficient hybrid white organic light-emitting diode (HWOLED) has been demonstrated with a mixed interlayer between fluorescent blue and phosphorescent yellow-emitting layers. The device structure is simplified by using a controllable fluorescence-mixed interlayer-phosphorescence emission layer structure. The electroluminance (EL) performance can be modulated easily by adjusting the ratio of the hole-predominated material to the electron-predominated material in the interlayer. It is found that the HWOLED with a ratio of 3 : 2 exhibits a current efficiency of 34 cd/A and a power efficiency of 29 lm/W at 1000 cd/m2with warm white Commission Internationale de l’Eclairage (CIE1931) coordinates of (0.4273, 0.4439). The improved efficiency and adaptive CIE coordinates are attributed to the controllable mixed interlayer with enhanced charge carrier transport, optimized excitons distribution, and improved harvestings of singlet and triplet excitons.
Highlights
We investigate the effects of the ratio of the hole-predominated material to the electron-predominated material in mixed interlayer (MI) on the device efficiency and the white color coordinates in hybrid white organic light-emitting diode (HWOLED)
The interfacial energy barrier between emitting layers is critical to the driving voltage of white OLEDs (WOLEDs)
The current density-voltage (J-V) characteristics shown in Figure 2 exhibit that the driving voltage of HWOLEDs with intrinsic interlayers as spacers (Devices A and B) is higher than that of devices with MIs as spacers (Devices C, D and E) at the same current density
Summary
Since firstly reported by Tang and Vanslyke in 1980s [1], organic light-emitting diodes (OLEDs) especially the white OLEDs (WOLEDs) [2] have drawn increasing attention for wide commercial applications in displays and solid-state lighting, owing to their thinness, flexibility, low operation voltage, wide-viewing angle, high resolution, and a fast response time. We investigate the effects of the ratio of the hole-predominated material to the electron-predominated material in MI on the device efficiency and the white color coordinates in HWOLEDs. In addition, we employed an optimized emitting architecture of fluorescence blue-MIphosphorescence yellow (F-MI-P) instead of the generally used F-I-P-I-F architecture [14, 20,21,22] for simplifying the fabrication processes. The blue fluorescence and yellow phosphorescence, instead of conventional doping in the ambipolar host and/or the mixed bipolar property host materials [20,21,22,23,24, 26,27,28, 30, 31], are doped in the hole-predominated host and the electron-predominated host, respectively
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