Enhancing effects of nanoparticles on polymer-OLED performances

In an attempt to elucidate the influences of conductor Ag and semiconductor TiO2 nanoparticles (NPs) onto device characteristics, the polymer organic light emitting diodes (P-OLEDs) with composite layers were prepared and investigated. The mentioned inorganic NPs were embedded into the hole transport layer [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate); (PEDOT:PSS)] and into the emissive layer [poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene]; (MEH-PPV)], individually, with different concentrations. The fabrication of the P-OLEDs was achieved via solution processing. Complete device characteristics, namely, voltage-current, brightness, luminous efficiency, and electroluminescent spectrum were all determined and carefully analyzed to clarify the impacts on the device physics. Ag NPs synthesis was successfully carried out yielding approximately 6-nm diameter particle size. P-OLEDs fabricated using Ag/PEDOT:PSS and Ag/MEH-PPV nanocomposite layers exhibited enhancement in the device efficiency up to 45 %. Moreover, threshold and turn-on voltages were improved upon hybridisation of organic layers with TiO2 nanoparticles. On the other hand, electroluminescent spectrum was not affected significantly by Ag NPs while TiO2 shifted the dominant peak to the shorter wavelength.