Tuning the photoluminescence and anisotropic structure of PEDOT

Abstract

In the current work, we study the photoluminescence and anisotropic structure of PEDOT which is obtained in the presence of ions that perturb the water structure (ions in Hofmeister series). The water content in PEDOT has been confirmed by TGA and DSC measurements. The weight loss and heat flux together provided refined information about water content in the synthesized PEDOT, and based on the characteristic energy value, we conclude that the water molecules are bonded to the PEDOT chains by hydrogen bonds. The physicochemical properties of the such prepared PEDOT have been studied, e.g. the presence of photoluminescence is observed for PEDOT in the solid-state (thin film) with the longest Stokes shift (273 nm). Similarly, photoluminescence has been detected for the aqueous PEDOT suspension with the lifetime of the excited state in the range of nanoseconds. Moreover, the PEDOT chains can undergo rearrangements under electrochemical performance with the formation of an anisotropic structure, which is confirmed by polarized microscopy and XRD measurements. The photoluminescence spectrum of the anisotropic PEDOT film contains sharp, well-resolved peaks.