Facilely Tunable Redox Behaviors in Donor–Node–Acceptor Polymers toward High-Performance Ambipolar Electrode Materials

Abstract

Conjugation breaking by “node” structures in donor–node–acceptor (D–n–A)-type molecules conceptually enables facile tuning of their oxidation and reduction behaviors through modification of the donor (D) unit and the acceptor (A) unit independently. Herein, we demonstrate the successful synthesis of a series of D–n–A-type cross-linked polymers, termed poly-4T-PDI, poly-2T3-PDI, and poly-4T3-PDI, by an in situ electrochemical polymerization reaction on the surface of electrodes and their versatile redox properties. These polymers contain oligo-thiophene structures connected with tetrachloronated perylene diimide (PDI) units through the “N node”. The investigation of the redox behaviors of these three polymers clearly indicates that there are two reversible redox waves corresponding to the oxidation–reduction couples of PDI/PDI– and PDI–/PDI2–; however, the redox signal relating to the oligo-thiophene structures completely relies on the number and connection mode of thiophene units. Especially, poly-2T3-PDI possesses a balanced ambipolar characteristic showing approximately equivalent gravimetric capacitances of 299 F g–1 for the n-doping process and 264 F g–1 for the p-doping process, which facilitate the application of such ambipolar polymers as both cathode and anode materials in pseudocapacitors. In addition, electrochemical impedance spectroscopy indicates easy ion diffusion and fast electron transfer in the film of poly-2T3-PDI, which is attributed to the fine porous structure and the conjugated backbone of polythiophene. The current research clearly demonstrates a facile strategy to achieve balanced ambipolar polymers through conjugation breaking by the “node” structure between the electron donor and acceptor units.

Corannulene Extended Viologen-Based Ambipolar Polymers for Transparent-to-Color Electrochromic Supercapacitors

“…Electrochromic supercapacitors with visible energy storage levels and high charge/discharge rates have been used to power wearable and portable intelligent electronics. − Among these materials employed in electrochromic smart windows and supercapacitor devices, redox-active π-conjugated polymers have received great attention because they exhibit rapid electrochemical reactions, flexibility, and solution-processability, and they can change color and store energy through the faradaic reaction during the doping/dedoping process. − To achieve the optimal polymer-based supercapacitor configuration, researchers have designed a supercapacitor using an ambipolar polymer with a p-doped state and an n-doped state, which can store positive and negative charge in one material. − Taking advantage of dual doped states, the ambipolar supercapacitor enlarges the operating voltage window, leading to a higher energy density.…”

“…Therefore, connecting two redox-active π molecules showing transparency in the neutral state by nonconjugated alkyl chains not only separates the p-type and n-type materials but also prevents the color from being displayed in the neutral state and achieves a transparent-to-color electrochromic supercapacitor. Moreover, the conventional n-type moieties used for ambipolar supercapacitors were the derivatives of perylene diimide, ,, thiadiazole-based acceptors, , and anthraquinone . Because of the lack of reliable n-type moieties for the ambipolar supercapacitors, an investigation of newly synthesized n-type materials is necessary.…”

NiCo2O4 Hexagonal Nanoplates/Cornstalk-Derived Porous Carbon Composites for High-Performance Supercapacitor Electrodes

“…To deal with energy consumption and environmental contamination issues, research and development of the efficient and trustful energy storage devices becomes extremely urgent. − Currently, supercapacitors (SCs) have been getting widespread attention because of their attractive merits as compared to the conventional dielectric counterparts, including excellent power density, long cycle-service life, rapid charge–discharge capability, and green and pollution-free operation. , In general, in light of the distinction of electrochemical charge storage processes, the SCs are classified into three different types: double-layer capacitors (EDLCs), pseudocapacitors, and hybrid SCs. , The capacitance of EDLCs based on various carbon materials, for instance, carbon nanotubes, graphene, carbon nanofibers and porous carbon, is greatly influenced by pore structure characteristics of electrode materials. The pore structure of an electrode surface in contact with the electrolyte solution can generate tremendous impact on the charge storage properties . Compared with that of EDLCs, the higher energy density of pseudocapacitors can be attributed to the complex processes of electrosorption, redox reaction, and intercalation for charge storage.…”

“…The pore structure of an electrode surface in contact with the electrolyte solution can generate tremendous impact on the charge storage properties. 13 Compared with that of EDLCs, the higher energy density of pseudocapacitors can be attributed to the complex processes of electrosorption, redox reaction, and intercalation for charge storage. Therefore, a great deal of pseudocapacitor electrode materials is the result of a shift in focus in the past years.…”

Photoinduced Cascading Charge Transfer in Perylene Bisimide-Based Triads

“…Among multitudinous multichromophoric architectures, the D–A 1 –A 2 architecture is a feasible and facile strategy to increase the lifetime of CT states, which stem from the appropriate CT rate of two concatenate building units for further charge transfer to the third unit before charge recombination (CR) . Among various building blocks, perylene bisimide derivatives (PBIs) were widely utilized in the classical D–A photoelectric conversion device for the chemical/thermal stability, large molar extinction coefficient in the visible light region, and high electron mobility. − Furthermore, terminal imide (nitrogen atoms) known as nodes made PBI-based compounds ideal for receding molecular orbitals overlap through nonelectronic connection with donor chromophore units, which made complex photophysical processes being easier to interpret in PBI systems. ,,− …”