Enhancement of radiative efficiencies of near-ultraviolet organic light-emitting diodes by localized surfacee Plasmon resonance enhancement effect

Near-UV emission organic light emitting diodes (OLEDs) containing silver (Ag) nanoparticles (NPs) were fabricated to improve their radiative efficiencies by the localized surface plasmon resonance (LSPR) enhancement effect. The samples studied were simple bilayer structures consisting of an active layer and a hole-transporting layer (HTL). Poly[(9,9- dihexylfluoren-2,7-diyl)-co-(1,4-dimethyl-benzene-2,5-diyl)] (PF-DMB) was used as a UV emission material, whose emission peaking-wavelength is about 395 nm. Ag NPs were inserted between ITO and HTL, whose absorption peaking wavelength is corresponding to about 395 nm. Thus, the electroluminescence (EL) intensity of UV OLEDs containing Ag NPs was enhanced to about 2.5 times as large as that without Ag NP by the LSPR enhancement effect. (paper)