Organic light emitting diodes: the investigation of electro-luminescence properties in the magnetic fields

It is well known that magnetic field can change organic light emitting diodes spectral characteristics such as electroluminescence, photoluminescence, photocurrent and injection current. Only a small part of the organic light emitting diodes are investigated because of huge diversity of organic compounds. That makes this are of investigation very promising. The aim of this work is to investigate magnetic field effect in organic light emitting structures with ITO/TPD/Emitting layer/TmPyPB/Alq3/LiF/Al layer structure. Nine structures having different quinoline and naphthyridine emitting layers were investigated and compared with a control sample ITO/TPD/TmPyPB/Alq3/LiF/Al (structure without emitting layer). It was determined, that in the control sample with the absence of emitting layer, the negative magnetic field effect is being observed – the ratio of singlet-triplet jumps is decreasing. Structures with quinoline based emitting layers shows positive magnetic field effect – the ratio of singlet-triplet jumps is increasing. No magnetic field effect was observed when quinoline emitting layers were changed to naphthyridine layer