Precursor synthesis strategy for polycyclic aromatic conjugated polymers on the application of supercapacitors

Polycyclic aromatics (PCAs) possess excellent photoelectric properties, but the construction of such compounds has been a quite challenging subject of study, mainly due to very low solubility. Herein we report a precursor synthesis strategy for polycyclic aromatic conjugated polymers. A soluble precursor polymer, that containing fusible "double U-shaped aromatic"(DUA) and perylenetetracarboxydiimide (PDI) units, was firstly synthesized by Suzuki coupling. The stereo aromatic units in polymer backbone were found to be converted into polycyclic aromatic units, i.e. hexa-peri-hexabenzocoronene (HBC), by chemical or electrochemical oxidation, which resulted in a formation of insoluble polycyclic aromatic conjugated polymers. The electrochemical oxidations that occurred at the interface of electrode and solution exhibited higher cyclization reactivity and leads to the formation of high quality films on the electrode surface. Characterization by Raman and UV-visible (UV-Vis) spectroscopy validated the successful formation of this HBC structure. Some potential applications of such thin films are being explored, and here we focus on the characteristics of supercapacitors based on their excellent electrochemical properties.

A Cathodic Electrochromic Material Based on Thick Perylene Bisimide Film with High Optical Contrast and High Stability

Cathodic electrochromic materials realized by n-type doping of conducting polymers are scarce.Even with limited cases reported in the literature,long-term stability is an urgent problem to be solved.Herein,we report a high performance and stable cathodic electrochromic material,poly(Th-Cl-PBI),based on a perylene bisimide function core.Due to its high electropolymerization efficiency and low steric hindrance of thiophene groups,perylene bisimide,which generally does not dissolve and form film easily,can grow to the sufficient thickness of 350 nm for wide-range spectral modulation and large-capacity energy storage.The optical contrast of optimized film with a thickness of 240 nm reaches as high as 69.1% at 520 nm,94.1% at 760 nm,and 95.7% at 680 nm.Theoretical simulation based on the Lambert–Beer law also verifies this optical contrast dependent on film thickness.Besides,during the transition between the neutral state and radical anion state,it maintains 90.2% of the electrochemical activity after 4000 cycles,and the transmittance spectrum remains stable after 2000 cycles.The cation size effect on cathodic electrochromic process and cyclic stability has been investigated.

Preparation and electronic characteristics of anionic perylene bisimide films

Neutral perylene bisimides(PBI) are well-known n-type organic semiconductors, with number of challenging electronic properties in their neutral and reduced states. We report the characteristic electronic properties of PBI anionic films. We unexpectedly discovered that pristine PBI dianion film showed p-type character, while oxidized dianion film(dominant neutral state with few radical anions) showed normal n-type semiconductor character based on Seebeck effect measurements. Both kinds of films exhibit high electrical conductivity with a potential for thermoelectric applications. The mechanism of polarity reversal is proposed.