Ambipolar All-Organic Solid-State Electrochromic Device Using Electrodeposited Polyaniline: Improving Performance by Design

The versatility of polyaniline (PANI), a highly conducting polymer, lies in the fact that it responds to both positive and negative bias, making it a viable option for designing an ambipolar electronic device. This nature of the polymer has been exploited in the electrochromic domain to establish it as an ambipolar electrochromic material. Studies carried out on an electrodeposited PANI electrode show its ability to behave as an n-type as well as a p-type material. Furthermore, two electrochromic devices (ECDs) with PANI as the electrochromic layer and two opposite kinds of counterions, TTF (tetrathiafulvalene) and PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), were fabricated and subsequently characterized. High contrast value (similar to 50%), smaller switching time (similar to 1 s), and moderate coloration efficiency values (similar to 100 cm2/C) were obtained from the device, which establish the ambipolar electrochromic aspect of PANI-based solid-state electrochromic devices. To demonstrate the versatile nature of PANI, devices were fabricated using n- and p-type electrochromic active layers as well, which furnished similarly good results. Encouraging results can prove to be of importance in solid-state electrochromic device design engineering by reducing the number of constraints.