Since the discovery of the fact that the electrochromic (EC) behavior of polyisocyanides (PICs) can be achieved without the restriction of EC groups in 2018, a new chapter of electrochromic PICs has been opened. However, the synergistic electrochromic behaviors of both PICs and EC groups have not been reported until now. Herein, a series of novel EC poly­(phenyl isocyanide) helix cross-conjugated polymers (PICz) containing a strong donor (carbazole)–weak acceptor (phenyl isocyanide) structure feature are synthesized through living polymerization. As a p-type electrochromic polymer, PICz polymer films exhibit good electrochromic abilities, such as easily observed color changes (from orange-yellow to light gray), low onset potentials (0.78–0.80 V), fast switching time ((2.1–2.4)/(1.0–1.1) s for the electrochromic process), and high coloration efficiency (165.54–431.52 cm2 C–1). It is worth noting that besides the EC behavior from carbazole groups, the strong absorption in the near-infrared region (780–1800) is attributed to the EC behavior of the electrochemically doped PIC structures, which is beneficial to its further application in many military and civilian uses. In addition, PICz polymers can achieve higher switching cycling stability in solution (over 100 cycles) than that in a solid-state thin film (1 cycle), due to the remarkable switching of the polymer structure from the neutral state to the doped state, which is a unique feature compared with the other EC polymers.

No abstract

Recently, organometallic halide perovskites have shown attractive application prospects in photoelectric devices depending on their excellent electro-optic properties. However, their poor stability has greatly limited their practical applications. Here, methylammonium lead tribromide (MAPbBr 3) crystals are protected by polystyrene (PS) fibre membranes using electrospinning technology. The MAPbBr 3 @PS composite fibre membranes fabricated in this work not only show strong photoluminescence properties but also excellent stability: 70% of the fluorescence intensity of MAPbBr 3 @PS is maintained after soaking in water for 30 days, 85% after leaving at 95°C for 350 min, and 90% after irradiating under UV light for 100 h. The excellent stability of the MAPbBr 3 @PS fibre membranes may be attributed to the hydrogen bonds between the MAPbBr 3 crystal and the PS fibre. In addition, a high-brightness white-light-emitting diode based on MAPbBr 3 @PS fibre was fabricated, which fully demonstrates its application prospects in the field of colour conversion.

Functional polymers featuring good processability in non-halogenated, benzene-free green solvents are highly desired due to health and environmental concerns. Herein, a series of novel D-A type conjugated polymers, PBDT-IIDs, are designed and successfully prepared by “green” functionalization of the polymers with highly hydrophilic, highly polar, highly flexible, and biocompatible oligoethylene glycol (OEG) side chains in order to improve the processability. These series polymers are named PBDT-IID2, PBDT-IID3, and PBDT-IID4, respectively, according to the number of oxygen atoms in the side chain. After confirmation by structural characterization, the basic properties of PBDT-IIDs are also investigated. With the increase in the OEG side chain length, the polymer PBDT-IID4 not only has good solubility in the halogen solvent chlorobenzene, but also exhibits excellent solubility in the green halogen-free solvent methyltetrahydrofuran (Me-THF). As a result, the green solvent Me-THF can also be applied to prepare PBDT-IIDs’ electrochromic active layers, except for chlorobenzene and toluene. The electrochromism of PBDT IIDs under both positive and negative voltages has a practical application potential. The several controllable switches between dark green and khaki (0–0.6 V) are expected to show great potential in the field of military camouflage. Furthermore, according to the principle of red, green, and blue (RGB) mixing, light blue-green in the reduced state (−1.6 V) can be used in the preparation of complementary ECDs to provide one of the three primary colors (green).