Magnetic field effects on electroluminescence emanated simultaneously from blue fluorescent and red phosphorescent emissive layers of an organic light-emitting diode

A simple method by employing white organic light-emitting diode (OLED) to simultaneously study the effects of magnetic fields (MFEs) on the fluorescent and phosphorescent emission was presented. The white OLED consisting of the blue fluorescent and red phosphorescent materials was fabricated. The low-pass filter chopped at 500 nm and the high-pass filter chopped at 550 nm were used to separate the MFEs on the blue fluorescence and red phosphorescence, separately. The magnetoelectroluminescences (MELs) on the fluorescence sharply increased at low magnetic field then tended to saturation at high magnetic field. While the MELs on the phosphorescence sharply increased at low magnetic field then slowly monotonically increased as the magnetic field further increased. Our results indicated that the magnetic-field modulated singlet-to-triplet electron-hole pair conversion combining with the magnetic-field modulated triplet-triplet annihilation process are the origins of the MFEs on the electroluminescence. (C) 2012 Elsevier B.V. All rights reserved.