Enhanced polymer light-emitting diode property using fluorescent conducting polymer-reduced graphene oxide nanocomposite as active emissive layer

摘要

The present article reports the polymer light-emitting diode property of the nanocomposite comprising poly 9,9-dioctyl fluorene-alt-bithiophene and reduced graphene oxide used as an emissive layer. Two times repetition of Hummers oxidation and hydrazine hydrate reduction method produce reduced graphene oxide (term as rGO_2) with more uniform distribution in size and thickness. In addition, this uniquely synthesized rGO_2 induces favorable shift in balance of electron and hole recombination zone toward the center of emissive layer owing to increase in in-plane crystallite size and high localize aromatic confinement. Five times increase in maximum device efficiency (Cd/A) and three times increase in maximum brightness (Cd/m2) are achieved with the LED device using nanocomposite as emissive layer compared to neat polymer. Also, the fabricated device requires relatively low turn-on voltage (4 V) because of low energy barrier between PEDOT work function (-5.0 eV) and HOMO levels of bi-thiophene copolymer -5.67 eV) and nanocomposite (-5.66 eV).