Highly stable and conductive PEDOT:PSS/GO-SWCNT bilayer transparent conductive films
Carbon nanotubes (CNTs) and graphene oxide (GO) were sprayed on flexible polyethylene terephthalate (PET) substrates to prepare CNT and GO–CNT transparent conductive films (TCFs). For the GO–CNT TCFs, when the mass ratio of GO to CNTs was 0.2, a relatively low sheet resistance of 90.4 Ω sq−1 at a transmittance of 87% (550 nm) was obtained with an average σdc/σopt value of 28.9. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) solution without or with ethylene glycol (EG) added was sprayed on the surface of the GO–CNT films to obtain P/GO–CNT and P(E)/GO–CNT films, respectively. P(E)/GO–CNT films were post-treated with sulfuric acid to obtain P(E,S)/GO–CNT TCFs. The addition of PEDOT:PSS can permeate into the pores of networks and densify the GO–CNT networks, increasing the conductivity and wettability and decreasing the roughness of the films. Additional EG can reduce the Coulomb force between PEDOT and PSS and change the morphology of PEDOT, and at the same time sulfuric acid treatment can effectively remove PSS from the PEDOT:PSS layer. The P(E,S)/GO–CNT 0.2 TCFs exhibited a sheet resistance of 46.3 Ω sq−1 at a transmittance of 87.5% (550 nm) with an average σdc/σopt value of 56.1. The organic light emitting diodes were successfully fabricated, and the mechanism of how the electrical conductivity of the hybrid film increased was also investigated.