Improving PLED performance by coating a graphene oxide layer using the plasma method

In this paper, we report the fabrication and characterization of polymer light-emitting diodes (PLEDs) with the structure ITO/PEDOT:PSS/MEH-PPV/rGO/Al, aiming to reduce the turn-on voltage. In this work, the PEDOT:PSS layer as the hole injection layer was deposited, and the MEH-PPV layer as the active material was deposited using the spin deposition method. Then, the active layer of rGO, coated using the plasma method, was applied to MEH-PPV. The structural properties of the MEH‑PPV/rGO active layer were studied. The structural characteristics of this layer can influence its optical behavior and, consequently, the overall performance of the polymer light-emitting diode. The addition of the rGO layer to the polymer structure improved the optoelectronic properties of the material. XRD and FTIR results indicate that after reduction, the structure transitions from the oxidized state of GO to a more graphitic state, characterized by more regular sp² bonds and the removal of oxygen groups. These structural changes increased the electrical conductivity and reduced the resistance of the polymer diodes. Optically, the absorption in the sample containing rGO was higher in the 420–450nm region, indicating better light charge transfer. Although the light emission intensity decreased slightly, the peak positions remained constant; therefore, the presence of rGO improved the overall optical and electrical performance of MEH-PPV systems.