Electrochemical Synthesis And Electrochromic Properties Of Polythiophene Derivatives And Their Application In Electrochromic Devices

Tremendous interests have been focused on conducting polymers (CPs) due to their interesting electrical and optical properties. Polythiophene and its derivatives (PThs), as an important class of conducting polymers, have been widely researched because of their excellent properties, such as ease of chemical and electrochemical synthesis, redox stability, and processability. Recent advances in the field of PThs have led to a variety of materials with greater potential for practical applications, including polymer solar cells (PSC), sensors, organic light-emitting diodes (OLED), field effect transistor (FET), membranes and electrochromic devices (ECD).In light of the considerations mentioned above, in this study, several novel conducting polymers based on polythiophene were prepared via one-step electrochemical method and characterized. The opto-electrochemical and electrochromic properties of the resulting polymers were also investigated. Moreover, dual type electrochromic devices (ECDs) based on these resulting polythiophenes and poly(3,4-ethylenedioxythiophene)(PEDOT) was constructed and characterized in detail.1. Four novel thiophene-based monomers tris[4-(2-thienyl)phenyl]amine (TTPA),1-(thiophen-2-yl)pyrene (TP),1,6-bis(2-thienyl)pyrene (TPT) and1,6-bis(2-(3,4-ethylenedioxy)thienyl)pyrene (EPE) were synthesized via Suzuki or Stille coupling reaction and electropolymerized. Characterizations of the resulting polymers poly(tris[4-(2-thienyl)phenyl]amine)(PTTPA), poly(1-(thiophen-2-yl)pyrene)(PTP), poly(1,6-bis(2-thienyl)pyrene)(PTPT) and poly(1,6-bis(2-(3,4-ethylenedioxy)thienyl)pyrene)(PEPE) were performed by cyclic voltammetry (CV), UV-vis and FT-IR spectroscopy, elemental analyses and scanning electron microscopy (SEM). Spectroelectrochemical analysis was carried out to investigate the electrochromic properties of these resulting polymers. Moreover, electrochromic devices (ECDs) based on these polymers (the anodically coloring materials) and PEDOT (the cathodically coloring material) were also constructed. The fundamental performance parameter of these ECDs were investigated in detail, such as optical contrast, response time, coloration efficiency, open circuit memory and redox stability.2. Two novel copolymers were successfully synthesized via the electrochemical oxidation of their respective monomer mixtures:(1). P(NMPy-co-CPDT), synthesized by N-methylpyrrole (NMPy) and cyclopenta[2,1-b:3,4-b’]dithiophene (CPDT) mixture;(2). P(TTPA-co-EDOT), synthesized by tris[4-(2-thienyl)phenyl]amine (TTPA) and3,4-ethylenedioxythiophene (EDOT) mixture. The electrochromic and spectro-electrochemical properties of the copolymers were studied in detail. In addition, we constructed and extensively characterized dual-type ECDs based on P(NMPy-co-CPDT)(and P(TTPA-co-EDOT)) with poly(3,4-ethylenedioxythiophene)(PEDOT).