Electrochromic films with better stability and rapid response are based on silane coupling agent linked lanthanum oxide/polyaniline composite

A fast response and stability enhanced electrochromic film based on a composite of polyaniline (PANI) with surface functionalized Lanthanum oxide (f-La 2 O 3 ) nanoparticles has been prepared by in-situ polymerization. Scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FTIR) confirmed that La 2 O 3 was attached to the surface of PANI by silane coupling agent. Meanwhile, Electrochemical and electrochromic properties were investigated using cyclic volatammetry, chronoamperommetry, electrochemical impedance spectroscopy (EIS) and UV–vis spectroscopy. Compared with PANI, the f-La 2 O 3 /PANI composite showed excellent electrochromic performance, shorter response time and higher stability. As the mol ratio of La 2 O 3 to aniline was 1:3.5, the composites exhibited best electrochromic behavior with superior coloration efficiency of 22.81 cm 2  C −1 and fastest response time of 1.29 s/1.33 s for bleaching and coloration respectively. The result indicates that introduction of rare earth elements has great potential to improve the electrochromic properties of conducting polymers .