Effects of Secondary Dopant Anions on Emissivity and Related Properties of Poly(3,4-ethylenedioxythiophene)

Smart materials that are energy efficient and take up less space are crucial in the development of new technologies. Electrochromic polymers (ECPs) are one such class of materials that actively change their optical behavior in both visible and infrared parts of the electromagnetic spectrum. They show promise in a wide range of applications, from active camouflage to smart displays/windows. The full capabilities of ECPs are still yet to be explored, for while their electrochromic properties are well established, their Infrared (IR) modulation is less reported on. This study addresses the potential of ECPs in active IR modulating devices by optimization of Vapor Phase Polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via the substitution of its dopant anion. Dynamic ranges denoting emissivity changes between reduced and oxidized states of PEDOT are found across dopants of tosylate, bromide, sulfate, chloride, perchlorate, and nitrate. Relative to the emissivity of reduced (neutral) PEDOT, a range of ±15% is achieved from the doped PEDOT films, and a maximum dynamic range of 0.11 across a 34% change is recorded for PEDOT doped with perchlorate.