Fabrication of Near-infrared Polymer Light-emitting-diodes Using DispersedLaser Dye

摘要

The purpose of this research is to fabricate polymer light-emitting diodes (PLEDs) operating in the near-infrared (NIR) region. IR-140 is a laser-dye, whose emission wavelength is 870 nm. This NIR dye was dispersed as an emissive dopant within poly(2-methoxy-5-(3'-7'-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO -PPV) and poly(N-vinylcarbazole) (PVK). In addition, 2-(4- tert-butylpheny1)-5-(4-biphenyly1)-1,3,4-oxadiazole (PBD) was dispersed in the active layer. We fabricated the following two types of samples: (A) indium tin oxide (ITO)/MDMO-PPV:IR-140/aluminum (Al) and (B) ITO/IR-140:PBD:PVK/Al. Sample A successfully showed NIR emis-sions. However, sample A also revealed EL signals in the visible light region. In sample B, however, the undesired visible light was successfully eliminated due to the improved carrier-balance in the active region.