Electropolymerized Triphenylamine Network Films for High‐Performance Transparent to Black Electrochromism and Capacitance

Abstract

can only be called black ECMs. Therefore, in addition to the general electrochromic performance parameters such as contrast ratio, response time, and cyclic stability, for transparent to black ECMs, the satisfactory bleached state is as important as the good black colored state.Conjugated triphenylamine (TPA)based polymers are a kind of potential transparent to black ECMs. [5] TPA cation has strong absorption range of 500-720 nm; [6] N,N,N′,N′-Tetraphenylbenzidine (TPB) is a common bridged structure of polytriphenylamine, its monovalent cation has an absorption in the range of 400-550 and 900-2000 nm, and the absorption of divalent cation is similar to TPA cation covering 550-850 nm range. [7] Both TPA and TPB have no absorption in visible and near-infrared (NIR) regions, hence triphenylamine-based materials may achieve the conversion between transparent and black and NIR electrochromism. [8] Liou and Yen et al. have chemically synthesized a large number of triphenylamine-based materials, [9] including several transparent to black ECMs with outstanding properties. [10] At present, due to the spectral redshift caused by substituents and aggregation, there is still a lack of triphenylamine-based materials with good bleached state, especially low absorption in the range of 400-500 nm.In this work, a precursor, HPB-6TPA, composed entirely of the TPA group was synthesized. Several HPB-6TPA derivatives and substances with similar chemical structures have been reported in the literature, [11] in which electrochemical and spectral properties and potential applications in organic semiconductors have been studied, and the electron transfer and spin states of cationic radicals have been also investigated. The monomer HPB-6TPA was polymerized in situ on an ITO electrode to form a flat polytriphenylamine film by electrodeposition. This film has weak absorption only ranging of 400-425 nm in the visible region; and can realize the conversion of high and low transmittance in the range of 400-2000 nm covering the vis-NIR region, owing to the potential response of TPA and dimeric TPA (TPB) structural units in this TPA network film. The electrochromic performance parameters of this film are impressive. And its specific capacitance is up to 788.9 F g −1 @1.4 A g −1 . In addition, by changing the conditions of EP, films with different contents of electroactive units can be prepared onThe polytriphenylamine films are prepared by electropolymerization from a precursor HPB-6TPA with hexaphenylbenzene (HPB) core bearing six triphenylamine (TPA) units. The abundant and valuable electrochromism from transparent to black and from no to strong near-infrared absorption are achieved from this TPA network film. The presence of residual TPA and dimeric TPA (N,N,N′,N′-tetraphenylbenzidine) units in network film and their independent potential response attain the electrochromic behaviors. The network film possesses short response time and can realize high doping level (72%), attributed to favorable dopant ion channel caused by the twisting struct...

Energy-efficient UV-to-NIR active smart electrochromic tetrabenzofluorene molecules

“…30,35 However, polymeric or hybrid electrochromic systems have seemed to deliver better energy storage properties. 36–43 In this direction, our research group is currently focusing on developing EC hybrid materials to improve energy storage.…”

“…However, not much research has been reported on organic small molecules as multifunctional EC systems with energy storage ability to compare our 30,35 However, polymeric or hybrid electrochromic systems have seemed to deliver better energy storage properties. [36][37][38][39][40][41][42][43] In this direction, our research group is currently focusing on developing EC hybrid materials to improve energy storage.…”

Non-conjugated triarylamine-based intrinsic microporous polyamides for an electrochromic supercapacitor: diffusion dynamics and charge–discharge studies

“…Based on the references, the first sharp peak drop from the discharge profile is mainly attributed to the material's double-layer capacitive discharge, followed by the phase transformation plateau with an extended discharge time for reactant diffusion into the inner pores for the battery-type reaction, and the final drop can be attributed to the concentration polarization of the material. 54–56…”

“…Based on the references, the rst sharp peak drop from the discharge prole is mainly attributed to the material's double-layer capacitive discharge, followed by the phase transformation plateau with an extended discharge time for reactant diffusion into the inner pores for the battery-type reaction, and the nal drop can be attributed to the concentration polarization of the material. [54][55][56] In Fig. S33a, † TPPA-Ether exhibited a symmetric chargedischarge characteristic pattern with a specic capacitance (C sp ) of 111.8 F g −1 at 1.0 A g −1 and a coulombic efficiency of 93.5% and could remain high C sp of 97.5 F g −1 even in the case of high current density (10 A g −1 ).…”

Substituents and Resonance Effects on the Electrochemical Stability of Polyelectrochromic Triarylamine-Based Polymers

“…Organic materials such as conducting polymers and viologens have recently become an intensive research topic. − The conducting polymers have several advantages over inorganic compounds as EC materials, including good electrochemical stability, fast switching speed, high coloring efficiency (CE), easy large-area processing, and color tuning through chemical modification. Also, triphenylamine (TPA)-containing polymers have been developed as an attractive family of EC materials because of their colorless neutral state and intriguing EC behaviors. − In recent years, redox-active materials with optical absorption change in the near IR (NIR) region have drawn significant attention due to their potential applications in optical communication, data storage, and thermal control in buildings and spacecraft. ,− For example, Wan et al reported that the quinone-containing EC materials revealed high absorption in NIR upon electrochemical reduction . Reynolds and Beaujuge reported that the conjugated polymers could exhibit multicolor in the neutral state and transmission in the oxidized state. , Liou and Lin also noted that the TPA-based polymers demonstrated an attractive anodic EC system for NIR applications due to their particular intramolecular electron transfer in the oxidized forms …”