Improved Electro-optical Performance of OLEDs Using PdCo Alloy Nanoparticles Supported on Polypropylenimine Dendrimer–Grafted Graphene

Abstract

We fabricated organic light emitting diodes (OLEDs) with PdCo alloy nanoparticles supported on polypropylenimine dendrimer–grafted graphene (PdCo/PPI–g-G) that was doped at different concentrations (0, 0.02, 0.03, 0.06 and 2 wt%) in a poly(3,4-ethylene dioxythiophene): polystyrene sulfonic acid (PEDOT:PSS) as a host layer. PdCo PPI–g-G and PEDOT:PSS were studied as hole injection layers in OLEDs. The efficiency of hole injection from the anode is strongly dependent on the concentration of the PdCo/PPI–g-G. While a graphene oxide and pure PEDOT:PSS layer leads to higher driving voltage and decreased luminescence efficiency. PdCo/PPI–g-G of 0.02 wt% noticeably enhanced the hole injection and resulted in lower turn-on voltage, increased luminance, and current efficiencies. The 0.02 wt% PdCo/PPI–g-G based device has also a luminance of 3705 cd/m2 and maximum efficiency of 1.9 cd/A at 13 V which are the highest values among other PdCo/ PPI–g-G based devices.