Electroactive conducting copolymers of aniline (ANI) and diphenylamine (DPA) are prepared on indium tin oxide (ITO) surface from 1 mol/L H

2

SO

4

aqueous solution with different feed ratios of ANI to DPA by using a potentiostatic method. FTIR spectra and SEM measurements are used to confirm the formation of copolymers. Due to the combination of the

N

N

′-diphenyl benzidine and aniline units in the molecular chain

the copolymer films exhibit improved electrochemical and electrochromic properties

compared to PANI and PDPA. The copolymer [marked as P(ANI9-

co

-DPA1)] film prepared at a ratio of 9:1 (ANI/DPA) exhibits novel transmittance modulation both in visible and near-infrared (NIR) region between −0.8 V and 0.8 V (52% and 67% respectively) and fast response time (3.6 s for coloration and 2.3 s for bleaching at 600 nm). An electrochromic device (ECD) based on P(ANI9-

co

-DPA1) and PEDOT:PSS is also fabricated and shows a multicolor electrochromic performance

with a good optical contrast (29% in visible region and 40% in NIR region)

acceptable response time (8.3 s for coloration and 7.5 s for bleaching at 600 nm) and long-term stability. Clear color changes from transparent (−0.8 V)

bright green (0 V)

seagreen (0.4 V) to dark slate gray (0.8 V) are demonstrated.