Front Cover: In article number 1900289 by R. M. Gamini Rajapakse, Davita L. Watkins, and co‐workers, electrochemical copolymerization affords near infrared‐II (100–1700 nm) absorbing copolymers with intrinsic conductivities over a wide potential window, even where it is nominally undoped. This study showcases the advantages of electro‐polymerization toward tailoring of next generation optoelectronic materials.

Block copolymers comprising benzothiadiazole were successfully electro-copolymerized leading to (BTD-T2)n(BTD-F2)m, where n and m were varied in a perfectly controllable, well-defined manner.

In this study, the electrical, dielectric and morphological analysis of composite solid polymer electrolytes containing polyethylene oxide, alumina nano-fillers and tetrapropylammonium iodide are conducted. The temperature dependence of conductivity shows activation energy of 0.23, 0.20 and 0.29 eV for electrolytes containing 0, 5 and 15 wt.% alumina, respectively, when data fitted to the Arrhenius equation. These activation energy values are in good agreement with those determined from dielectric measurements. The result confirms the fact that conductivity is activated by both the mobility and the charge carrier density. The conductivity isotherms demonstrated the existence of two peaks, at 5 and 15 wt.% Al 2 O 3 composition. The highest conductivity values of 2.4 × 10 −4 , 3.3 × 10 −4 and 4.2 × 10 −4 S cm −1 are obtained for the sample with 5 wt.% Al 2 O 3 at 0, 12 and 24°C, respectively, suggesting an enhancement of conductivity compared with that of alumina free samples.

Thienothiadiazole‐bisthiophene (TTDT2) and diketopyrrolo–pyrrole–bisthiophene (DPPT2) are successfully electro‐copolymerized with terthiophene (T3) as an initiator and linker at low oxidative potentials. AC impedance analysis, absorption spectroscopy, and elemental composition via SEM‐EDX support the formation of donor–acceptor (D–A) type alternating block copolymers, poly(T3‐TTDT2), and poly(T3‐DPPT2). Unique optical properties that span into the near infrared‐II(>1000 nm) region and inherent electrical conductivity at the p‐type regime, n‐type regime, and in between the two regimes (i.e., typical insulator region) are observed. This study showcases the advantages of electro‐polymerization toward tailoring of next generation opto‐electronic materials.

As fluorescence bioimaging has increased in popularity, there have been numerous reports on designing organic fluorophores with desirable properties amenable to perform this task, specifically fluorophores with emission in the near-infrared II (NIR-II) region. One such strategy is to utilize the donor−π−acceptor−π−donor approach (D−π−A−π−D), as this allows for control of the photophysical properties of the resulting fluorophores through modulation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. Herein, we illustrate the properties of thienothiadiazole (TTD) as an effective acceptor moiety in the design of NIR emissive fluorophores. TTD is a well-known electrondeficient species, but its use as an acceptor in D−π−A−π−D systems has not been extensively studied. We employed TTD as an acceptor unit in a series of two fluorophores and characterized the photophysical properties through experimental and computational studies. Both fluorophores exhibited emission maxima in the NIR-I that extends into the NIR-II. We also utilized electron paramagnetic resonance (EPR) spectroscopy to rationalize differences in the measured quantum yield values and demonstrated, to our knowledge, the first experimental evidence of radical species on a TTD-based small-molecule fluorophore. Encapsulation of the fluorophores using a surfactant formed polymeric nanoparticles, which were studied by photophysical and morphological techniques. The results of this work illustrate the potential of TTD as an acceptor in the design of NIR-II emissive fluorophores for fluorescence bioimaging applications.

A longstanding challenge in the field of optoelectronic materials, the effects of solid-state arrangement and morphology are still a prominent factor associated with small-molecule and polymer-based device performance. Here, mixed...