Fabrication of architectural structured polydopamine-functionalized reduced graphene oxide/carbon nanotube/PEDOT:PSS nanocomposites as flexible transparent electrodes for OLEDs

High performance, flexible transparent conductive films with a structure similar to that of reinforced concrete and constructed by sandwiching single-walled carbon nanotubes (SWCNT) between poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) and polydopamine functionalized reduced graphene oxide (PDA-RGO) were fabricated using simple spray coating. Mussel-inspired polydopamine was introduced as a graphene oxide reducing agent and modifier; the obtained PDA-RGO improved the interfacial adhesion between the conductive coating layers and substrate, and an effective post fabrication treatment method was performed on the hybrid film to achieve better conductivity. It was found that the resulting electrode exhibited a low sheet resistance of 52.2 Ω/sq. with a high optical transmittance of 88.7% at 550 nm. Moreover, the transparent film exhibited long-term stability with a relatively low roughness (ca. 2.41 nm), and its architectural structure sustained the flexibility of the film during bending. The organic light emitting diodes which using PDA-RGO/SWCNT/PEDOT:PSS film as anode was successfully fabricated, the luminance of the device was 2032 cd/cm² at 15 V and the maximum current efficiency was 2.13 cd/A at 14 V, indicating the strong potential of this type of transparent electrode for flexible electroluminescent devices.