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Nanostructured electrochromic polymer (ECP) materials are commonly explored in electrochromic devices (ECDs) because of their fast switching speed, high coloration efficiency and long cycle life. However, the preparation of nanostructured ECP films with a single component is still a great challenge. Herein, we present a facile, efficient, low-cost strategy to construct three-dimensional reticular macroporous (3DRM) ECP films without using templates. Polyterthiophene (PTTh) is selected as the model polymer due to its good EC behaviour. The 3DRM PTTh films on indium tin oxide (ITO) glass are fabricated by potentiostatic deposition (PSD) and pulsed electrodeposition (PED) of terthiophene (TTh), and further assembled into the ECDs. We investigate the morphology, structure and electrochemical properties of PTTh films, and EC performance of corresponding ECDs. The results indicate that the PTTh film with a PED time of 240 s (PTTh-PED-240) possesses loose 3DRM morphology and large surface area. The EC properties of corresponding ECD is significantly enhanced, exhibiting a large optical contrast, high coloration efficiency, short switching time, and improved cycling. Compared with the ECD based on PTTh film with a PSD time of 120 s on ITO glass (PTTh-PSD-120/ITO), the optical contrast of ECD based on PTTh-PED-240/ITO (ECD-240) increases by 45% (31 → 45%), and its coloration efficiency increases by 107% (258 → 534 cm2/C). This study suggests that PED might be a facile strategy for fabricating high-performance nanostructured ECP films, and its preparation process is low-cost, easily conducted under ambient conditions, showing great potential applications in nanostructured polymer-based ECDs. [Display omitted] • A facile, efficient and low-cost strategy was proposed to construct nanostructured ECP films without using templates. • The as-prepared PTTh-PED films possessed loose 3DRM morphology and large surface area. • The ECD based on PTTh-PED-240/ITO exhibited a superior electrochromic performance. • The relationship of microstructure, surface morphology and thickness of 3DRM PTTh films to EC properties was revealed. [ABSTRACT FROM AUTHOR]

Graphical abstract Poly (3-methylthiophene) covalently bonded to ITO electrode modified with 2-thiophenecarboxylic acid was synthesized and employed in the fabrication of high-performance polymer electrochromic device. Highlights • The PMeT film covalently bonded to ITO electrode was prepared using ThCA as modifier. • The adsorption force between the PMeT film and ITO electrode was enhanced. • The ECD based on PMeT-ITO exhibited better electrochromic stability. Abstract In this paper, we modified the surface of Indium tin oxide (ITO) electrode with 2-thiophenecarboxylic acid (ThCA), and then prepared the poly (3-methylthiophene) (PMeT) film covalently bonded to ITO electrode (PMeT-ITO) by electrochemical polymerization. It was found that interfacial modification enhanced the adsorption force between PMeT and ITO substrate, PMeT-ITO exhibited better stability. Moreover, we successfully fabricated the electrochromic device (ECD) by using PMeT films on ITO substrate. The results of cycling tests showed that the optical contrast of ECD based on PMeT-ITO was kept almost the same after recycling 66 times. Compared with ECD based on PMeT physically adsorbed on bare ITO substrate (PD-PMeT), the ECD based on PMeT-ITO possessed good electrochromic stability in the 150 cycles. This demonstrated that the interaction between PMeT and ITO substrate became stronger by chemical bonding approach, improving the cyclic stability of ECD. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) substrate was modified with 4-aminobenzylphosphonic acid (ABPA), and then the polyaniline (PANI) film covalently bonded to ITO substrate was prepared by the chemical oxidation polymerization. X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR) spectroscopy, and atomic force microscopy (AFM) measurements demonstrated that chemical binding was formed between PANI and ABPA-modified ITO surface, and the maximum thickness of PANI layer is about 30 nm. The adhesive strength of PANI film on ITO substrate was tested by sonication. It was found that the film formed on the modified ITO exhibited a much better stability than that on bare one. Cyclic voltammetry (CV) and UV–vis spectroscopy measurements indicated that the oxidative potentials of PANI film on ABPA-modified ITO substrate were decreased and the film exhibited high electrochemical activities. Moreover, the optical contrast increased from 0.58 for PANI film (without ultrasound) to 1.06 for PANI film (after ultrasound for 60 min), which had an over 83% enhancement. The coloration time was 20.8 s, while the bleaching time was 19.5 s. The increase of electrochromic switching time was due to the lower ion diffusion coefficient of the large cation of (C 4 H 9 ) 4 N + under the positive and negative potentials as comparison with the small Li + ion. [ABSTRACT FROM AUTHOR]

In this work, polythiothene (PT) films on indium tin oxide (ITO) substrate (PT-5/ITO, PT-10/ITO, PT-15/ITO, and PT-20/ITO) are prepared by pulsed electrodeposition, where + 1.5 V as the first square waveform pulse is applied to the cell for 5, 10, 15, and 20 s, respectively. These obtained electrodes are further assembled into the electrochromic devices (ECDs). We investigate the surface morphology, electrochemical properties of PT films, and EC performance of corresponding ECDs. The results indicate that PT films possess loose surface morphology, large surface area and high electrochemical activities. Among four kinds of films (PT-5, PT-10, PT-15 and PT-20), PT-10 film has the most uniform distribution of nanoparticles and smaller particle size. The EC properties of ECDs are significantly improved, which exhibits a large optical contrast, high coloration efficiency, short switching time, and stable cycling. The ECD based on PT-10/ITO (ECD-10) has the best EC performance, caused by the nanostructured morphology of PT-10 film that is most conducive to electron conduction, ion diffusion and migration. Compared with the ECD based on PT film obtained by potentiostatic deposition on ITO glass, the optical contrast of ECD-10 increases by 94% (17 → 33%), and its coloration efficiency increases by 88% (159 → 299 cm2/C). Among all ECDs, the response time of ECD-10 is the shortest, and its coloration and bleaching time are 1.12 and 0.80 s, respectively. This study suggests that pulsed electrodeposition might be a facile strategy for fabricating high-performance polymer-based ECDs. Image 1 • PT films on ITO substrate were prepared by pulsed electrodeposition, and assembled into the ECDs. • PT films possessed loose surface morphology, large surface area and high electrochemical activities. • The ECDs exhibited a large optical contrast, high coloration efficiency, short switching time, and stable cycling. • The relationship of microstructure and surface morphology of PT films to their EC properties was revealed. [ABSTRACT FROM AUTHOR]

In this work, electrochromic polymer (ECP)/exfoliated graphene (EG)/silver nanowires (AgNWs) composite film on indium tin oxide (ITO) substrate (ECP/EG/AgNWs/ITO) is prepared, and further assembled into the electrochromic device (ECD). We investigate the performance, bleaching and coloration kinetics of device based on the composite film using polythiothene (PT) as model polymer. The results indicate that the ECD based on PT/EG/AgNWs/ITO possesses large optical contrast (36%), high coloration efficiency (234 cm2/C), fast response time (the coloration and bleaching time are 6.63 and 0.71 s), and exhibits stable cycling. In comparison with the device based on PT film on bare ITO (PT/ITO), the optical contrast of device based on PT/EG/AgNWs/ITO is doubled (18 → 36%), and its coloration efficiency increases by 42% (165 → 234 cm2/C). Additionally, we can find that the dynamic processes of bleaching and coloration are all divided into three parts: I, primary stage; II, middle stage; III, late stage. The primary bleaching and coloration are completed in the first two stages. In stage II, the rate constants of bleaching and coloration can be obtained from the linear regression curves, and these rate constants of ECD based on PT/EG/AgNWs/ITO are higher. This study lays a foundation for quantitative analysis of bleaching and coloration processes and the construction of EC kinetic model. Image 1 • PT/EG/AgNWs composite film coated electrode was fabricated for polymer-based ECD. • The ECD exhibited a large optical contrast, high coloration efficiency, and fast response time. • The bleaching and coloration kinetics of ECD based on PT/ITO or PT/EG/AgNWs/ITO were investigated by the Avrami model. • The EC dynamic processes of device were divided into three parts, and the rate constants in stage II were obtained. [ABSTRACT FROM AUTHOR]

In this article, electrochromic polymer bilayer film on indium tin oxide (ITO) coated glass is built as electrode to facilitate the diffusion and migration of ions in electrochromic devices (ECDs). We investigate the performance of device based on the bilayer film using polythiothene (PT) and poly(3-thiophene boronic acid) (P3TBA) as model polymers. Notably, the incorporation of thin P3TBA layer (P3TBA has a high polarity) can change the surface morphology of PT film (rough and uncompacted), and increase the surface area of PT/P3TBA film, which will benefit the diffusion and migration of ions in ECD based on PT/P3TBA bilayer film on ITO glass (PT/P3TBA/ITO). As a result, the performance of ECD based on PT/P3TBA/ITO is significantly improved, which exhibits a highly optical contrast (48%), coloration efficiency (298 cm2/C), short response time (the coloration time and bleaching time are 5.27 and 0.48 s), and stable cycling. Compared with ECD based on PT film on ITO glass (PT/ITO), the optical contrast of ECD based on PT/P3TBA/ITO increases 200% (16% → 48%), and its coloration efficiency increases 54% (193 → 298 cm2/C). This study suggests that rational design of bilayer film micromorphology on electrode level might be a useful strategy for fabricating high performance polymer ECDs. The electrochromic device based on polymer bilayer film is fabricated and exhibits highly optical contrast, coloration efficiency, and short response time. Image 1 • PT/P3TBA bilayer film coated electrode was fabricated for polymer-based ECDs. • The electrode had large surface area and high electrochemical activities. • The ECD exhibited a highly optical contrast, coloration efficiency, and short response time. [ABSTRACT FROM AUTHOR]

Conducting polymers (CPs) are promising candidates for next-generation electrochromic (EC) materials due to their excellent processability, flexibility, multicolor changes, easy design, low cost and low operation potential. However, the relatively low optical contrast, slow switching speed, and poor cycling performance hinder their practical applications for more than forty years. Here, electrochromic polymer (ECP)/silver nanowires (AgNWs) stacking composite films on indium tin oxide (ITO) coated glass are built as electrodes to facilitate the diffusion and migration of ions in electrochromic devices (ECDs). Notably, the presence of AgNWs network plays a critical role to improve electrical conductivity, benefit ions doping and dedoping, increase surface area, and reduce applied potential. As a result, the EC performance of ECP/AgNWs nanocomposite device is significantly improved, which exhibits a highly optical contrast, short response time, and stable cycling. This study suggests that rational design of stacking nanocomposite micromorphology on electrode level might be a useful strategy for fabricating high performance ECDs. The electrochromic polymer/AgNWs nanocomposite devices are fabricated and exhibit highly optical contrast, short response time, and stable cycling performance. Image 1 • ECP/AgNWs stacking composite films were fabricated for polymer-based ECDs. • The composite electrodes had high electrical conductivity and large surface area. • The ECDs exhibited a highly optical contrast, short response time, and stable cycling. [ABSTRACT FROM AUTHOR]