Effect of a biopolymer on the electrochromic performance of water soluble naphthalene diimides

Amino acid appended naphthalene diimides (NDIs) undergo a reversible colourless-to-dark transition following reduction and are therefore suitable candidates for use in electrochromic devices. To fabricate these devices, it is necessary to employ a polymer additive to improve robustness and flexibility. Hyaluronic acid (HA) is an ideal polymer for our purposes due to its high degree of water solubility, allowing for the construction of films without the use of organic solvents. It is important to investigate how the addition of HA to our systems influences the self-assembly of the NDI, and therefore its electrochromic properties, to allow us to choose suitable processing formulations when fabricating electrochromic devices. When a higher concentration of HA is added, there is a change in the molecular packing and oxidation times of the resulting films. We expect that the polymer is changing the self-assembly of the NDIs. Therefore, we hope to probe the effects of increasing polymer concentrations on the structures formed by the NDIs to understand these observations and give us the best performance in our devices.