N,N,N′,N′- Tetraphenyl-1,4-phenylenediamine−Fluorene Alternating Conjugated Polymer: Synthesis, Characterization, and Electrochromic Application

High-Performance Black Copolymers Enabling Full Spectrum Control in Electrochromic Devices

Black-to-transparent electrochromism is hailed as the holy grail of organic optoelectronics. Despite its potential, designing black electrochromic materials that fully absorb visible light remains a significant challenge. Electroactive materials that simultaneously possess excellent cyclic stability, fast switching times, and high coloration efficiency are rare. In this study, we successfully designed copolymers that fully absorb the entire visible spectrum by judiciously selecting four types of monomers. We incorporated two types of polar side chains to synergistically enhance the ionic conductivity of the copolymers, thus improving the performance of electrochromic devices. Among these electrochromic devices, the P2-a device exhibits cycling stability exceeding 105 cycles, and the P2-c device demonstrates a coloring/ bleaching time of 0.82 s/0.86 s and achieves a coloration efficiency of 1078 cm²/C. This study proposes a strategy for designing and synthesizing high-performance black electrochromic copolymers.

Electrochromic properties of pyrene conductive polymers modified by chemical polymerization

Pyrene is composed of four benzene rings and has a unique planar melting ring structure. Pyrene is the smallest condensed polycyclic aromatic hydrocarbon, and its unique structural properties have been extensively studied. Pyrene has excellent properties such as thermal stability, high fluorescence quantum efficiency and high carrier mobility. This paper mainly used thiophene, EDOT and triphenylamine groups to enhance the pyrene based π-conjugated system and control the molecular accumulation of organic semiconductors, and improve their charge transport performances. Five kinds of polymer were synthesized and correspondingly characterized. The five kinds of pyrene conductive polymer had outstanding properties in terms of solubility, fluorescence intensity and thermal stability, good film-forming properties, stable electrochromic properties and high coloring efficiency. The coloration efficiency (CE) of PPYTP was as high as 277 cm² C⁻¹, and the switching response time was short. The coloring time of PPYEDOT was 1.3 s and the bleaching time was 3.2 s. The lower impedance will also provide the possibility of such polymers being incorporated into electrochromic devices in the future. In short, the synthesized new pyrene conductive polymers will have wide application prospects in the field of electrochromic materials.

Pyrene is composed of four benzene rings and has a unique planar melting ring structure.

Palladium bis-pincer complexes with controlled rigidity and inter-metal distance

We report a series of redox-active bis(pincer) Pd(ii) complexes in which the redox active units are based on either a diarylamido or a carbazolide framework.

Photophysical and Electroluminescence Characteristics of Polyfluorene Derivatives with Triphenylamine

In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.

Colorless-to-colorful switching electrochromic polyimides with very high contrast ratio

Colorless-to-colorful switching electrochromic polymers with very high contrast ratio are unattainable and attractive for the applications of smart wearable electronics. Here we report a facile strategy in developing colorless-to-colorful switching electrochromic polyimides by incorporating with alicyclic nonlinear, twisted structures and adjusted conjugated electrochromophores, which minimize the charge transfer complex formation. It is noted that, by controlling the conjugation length of electrochromophore, the colorless-to-black switching electrochromic polymer film (PI-1a) exhibites an ultrahigh integrated contrast ratio up to 91.4% from 380 to 780 nm, especially up to 96.8% at 798 nm. In addition, PI-1a film with asymmetric structure also demonstrates fast electrochemical and electrochromic behaviors (a switching and bleaching time of 1.3 s and 1.1 s, respectively) due to the loose chain stacking, which provides more pathways for the penetration of counterion. Moreover, the colorless-to-black EC device based on PI-1a reveals an overall integrated contrast ratio up to 80%.

Electrochromic polymers (ECPs) receive great attention due to their facile colour tunablility, however colourless-to-black ECPs with high contrast ratio are still unattainable. Here the authors develop high contrast colourless-to-black switching polyimides by following specific molecular design criteria.

Transmissive-to-black fast electrochromic switching from a long conjugated pendant group and a highly dispersed polymer/SWNT

Electrochromic polymer (ECPblack) demonstrates an ultrahigh contrast ratio (over 80%) in most of the visible regions, and its electrochemical and electrochromic behaviors remarkably accelerate by doping nanotube/polytriarylamine.

Electrochromic and electrofluorochromic polyimides with fluorene-based triphenylamine

A series of novel polyimides (PIs) based on N,N-di(4-aminophenyl)-2-amino-9,9-dimethylfluorene and various dianhydrides were synthesized. These PIs were amorphous and readily soluble in many solvents. They displayed outstanding thermal stability and high glass transition temperatures (269–374°C). The polymer films showed reversible electrochemical redox and satisfactory electrochromic performance with long-term stability, high coloration efficiency, and acceptable switching times. The PI derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride exhibited maximum fluorescence at 400 nm with quantum yields up to 28.1%. Furthermore, the fluorescence can be effectively electroswitched between “on” and “off” states, exhibiting a high contrast ratio of 75.

A series of organosoluble polyamides with 4-(dimethylamino)triphenylamine

A series of novel aromatic polyamides containing 4-(dimethylamino)triphenylamine were prepared via the polycondensation reactions of the newly synthesized dicarboxylic acid, 4,4′-dicarboxy-4″-(dimethylamino)triphenylamine, and various diamines. Introduction of 4-(dimethylamino)triphenylamine units along the polymer chain enhanced the solubility of the polymers. The 10% weight loss temperatures of these polymers ranged from 432°C to 471°C with the char yields more than 63% at 800°C under nitrogen atmosphere. The polymers displayed low oxidation potentials because of the incorporation of dimethylamino at the para position of triphenylamine. Cyclic voltammograms of the polyamide films showed their onset potential around 0.38–0.47 V with color changing from nearly colorless to light blue.

Immobilized polyazomethines containing triphenylamine groups on ITO: synthesis and acidochromic, electrochemical, electrochromic and photoelectronic properties

A new series of polyazomethines (PAMs) containing triphenylamine (TPA) as easily-oxidized units were synthesized as highly soluble materials with electrochromism.

Novel poly(triphenylamine-alt-fluorene) with asymmetric hexaphenylbenzene and pyrene moieties: synthesis, fluorescence, flexible near-infrared electrochromic devices and theoretical investigation

A new triphenylamine-alt-fluorene conjugated polymer with hexaphenylbenzene and pyrene for near-infrared electrochromism supported by DFT calculation and simulated spectra.

Novel photochromic and electrochromic diarylethenes bearing triphenylamine units

Novel diarylethenes containing triphenylamine units have been synthesized and characterized, and possessed both photochromic and electrochromic properties.

Preparation and characterization, stable bismaleimide-triarylamine polymers with reversible electrochromic properties

A series of novel polyimides were synthesized from bismaleimide containing different diaminetriarylamines by Michael addition reaction. The prepolymer is readily soluble in many common organic solvents, such as CHCl3, Tetrahydrofuran (THF) and N, N-dimethyl formamide (DMF). Prepolymers can be solution-cast into transparent, tough, and flexible films. These aromatic polyimides display good thermal stabilities, i.e. 5% weight-loss temperatures in excess of 200 °C under nitrogen. All obtained polyimides revealed excellent stability of electrochromic characteristics, changing color from original yellowish to green. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the investigated the polymers were estimated by experimental method are in the range of -4.78 eV to -4.98 eV and -1.64 eV to -2.09 eV vs the vacuum level, respectively. All the polymer films reveal good electrochemical and electrochromic stability under repeatedly switching electrode voltages, with coloration change from the yellow neutral state to green oxidized state.