Electrochromic Characteristics of Nitrogen-Doped Graphene/TiO2 Nanocomposite Electrodes

Nitrogen-doped graphene (NDG)/titanium dioxide (TiO2) nanoparticles were coated on indium-tin oxide (ITO) glass substrates to fabricate NDG-TiO2 nanocomposite electrodes. 3-methylthiophene (3MT) was electrochemically deposited on the NDG-TiO2 films to form poly(3-methylthiophene) (P3MT/NDG/TiO2) composite electrochromic electrodes. The introduction of NDG and TiO2 mesoporous films significantly increased the initial maximum optical contrast (ΔT%) to 70% as compared 41% of pure ITO electrodes, whereas the P3MT/NDG/TiO2 composite electrodes enhanced the adhesion of P3MT polymers to the NDG/TiO2/ITO substrate, thereby increasing the long-term stability of the corresponding electrochromic devices. Experimental results reveal that P3MT/NDG/TiO2 composite electrodes retained up to 90% of ΔT%, relative to 70% remaining ΔT% of pure ITO electrodes. This illustrates the enhanced long-term stability achieved through the introduction of a NDG-TiO2 nanocomposite films in electrochromic devices. These devices demonstrated excellent response time characteristics and ΔT% value of 6 s and ca. of 70%, respectively. This work has shown that conductive polymer/NDG/TiO2 composite electrodes are well suited to electrochromic devices for the promotion of performance and stability.