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Abstract:The effect of TiO 2 nanoparticle (NP) content on the improvement of poly(9,9 -di-noctylfluorenyl-2,7-diyl) (PFO)/Fluorol 7GA organic light emitting diode (OLED) performance is demonstrated here. The PFO/Fluorol 7GA blend with specific ratios of TiO 2 NPs was prepared via a solution blending method before being spin-coated onto an indium tin oxide (ITO) substrate to act as an emissive layer in OLEDs. A thin aluminum layer as top electrode was deposited onto the emissive layer using the electron beam chamber. Improvement electron injection from the cathode was achieved upon incorporation of TiO 2 NPs into the PFO/Fluorol 7GA blend, thus producing devices with intense luminance and lower turn-on voltage. The ITO/(PFO/Fluorol 7GA/TiO 2 )/Al OLED device exhibited maximum electroluminescence intensity and luminance at 25 wt % of TiO 2 NPs, while maximum luminance efficiency was achieved with 15 wt % TiO 2 NP content. In addition, this work proved that the performance of the devices was strongly affected by the surface morphology, which in turn depended on the TiO 2 NP content.

Improvement on optoelectronic properties of poly (9,9′-di-n-octylfluorenyl-2.7-diyl)- (PFO-) based light emitting diode upon incorporation of TiO2nanoparticles (NPs) is demonstrated. The PFO/TiO2nanocomposites with different weight ratios between 5 and 35 wt.% were prepared using solution blending method before they were spin coated onto Indium Tin Oxide substrate. Then a thin Al layer was deposited onto the nanocomposite layer to act as top electrode. The nanocomposites were tested as emissive layer in organic light emitting diodes (OLEDs). The TiO2NPs played the most crucial role in facilitating charge transport and electrical injection and thus improved device performance in terms of turn-on voltage, electroluminescence spectra (EL), luminance, and luminance efficiency. The best composition was OLED with 5 wt.% TiO2NPs content having moderate surface roughness and well distribution of NPs. The device performance was reduced at higher TiO2NPs content due to higher surface roughness and agglomeration of TiO2NPs. This work demonstrated the importance of optimum TiO2NPs content with uniform distribution and controlled surface roughness of the emissive layer for better device performance.

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