[3]-Radialene-based dopant CN6-CP studied herein, with its reduction potential of +0.8 versus Fc/Fc+ and the lowest unoccupied molecular orbital level of -5.87 eV, is the strongest molecular p-dopant reported in the open literature, so far. The efficient p-doping of the donor-acceptor dithienyl-diketopyrrolopyrrole-based copolymer having the highest unoccupied molecular orbital level of -5.49 eV is achieved. The doped films exhibit electrical conductivities up to 70 S cm(-1) .

Herein we present a molecular doping of a high mobility diketopyrrolopyrrole−dithienylthieno[3,2-b]thiophene donor−acceptor copolymer poly[3,6-thiophene], PDPP(6-DO) 2 TT, with the electron-deficient compound hexafluorotetracyanonaphthoquinodimethane (F6TCNNQ). Despite a slightly negative HOMO donor −LUMO acceptor offset of −0.12 eV which may suggest a reduced driving force for the charge transfer (CT), a partial charge CT was experimentally observed in PDPP(6-DO) 2 TT:F6TCNNQ by absorption, vibrational, and electron paramagnetic resonance spectroscopies and predicted by density functional theory calculations. Despite the modest CT, PDPP(6-DO) 2 TT:F6TCNNQ films possess unexpectedly high conductivities up to 2 S/cm (comparable with the conductivities of the benchmark doped polymer system P3HT:F4TCNQ having a large positive offset). The observation of the high conductivity in doped PDPP(6-DO) 2 TT films can be explained by a high hole mobility in PDPP(6-DO) 2 TT blends which compensates a lowered (relatively to P3HT:F4TCNQ) concentration of free charge carriers. We also show that F6TCNNQ-doped P3HT, the system which has not been reported so far to the best of our knowledge, exhibits a conductivity up to 7 S/cm, which exceeds the conductivity of the benchmark P3HT:F4TCNQ system.

Control and tuning of surface properties is indispensable for the programmed and rational design of materials. Particularly, polymeric brush-modified colloids can be used as carrier materials for enzyme immobilization. Although it is of prime importance to control the brush architecture, there is still a lack of systematic investigations concerning the impact of grafting density on the properties of the designed interface, as well as on the immobilization of biomolecules. In this work, we investigate the surface properties of polymer brushes with different grafting densities prepared using a "grafting from" approach on flat and on colloidal particle substrates by varying the density of initiator groups. In this way, we control and tune interfacial properties of the carrier material such as swelling, charge, adhesion as well as adsorption of laccase from Trametes versicolor on the grafted polyelectrolyte layer. We show that there is no direct transferability of the results received from planar to curved substrates regarding the swelling behavior in dependence on the grafting density. The maximum of swelling degree of PDMAEMA layers is achieved at 0.34 nm and at 0.1 nm grafting density for planar and curved particle substrates, respectively. The adhesion properties of the polymeric layer on both substrates are also strongly influenced by the grafting density, i.e. a decrease of the grafting density causes a transition from the adhesive to non-adhesive state. As proven by the cryo-TEM and AFM force distance measurements, an immobilization of laccase from Trametes versicolor causes a decrease of the polymer swelling and therefore leads to the changes in the surface morphology, charge and adhesion performance of final polymer-enzyme layer. Moreover, the higher effectiveness and activity of laccase were observed for the intermediate grafting densities which seem to be preferable over the maximum brush densities.

The N-type semiconducting polymer, P(NDI2OD-T2), with different molecular weights (MW=23, 72, and 250 kg/mol) was used for the fabrication of field-effect transistors (FETs) with different semiconductor layer thicknesses. FETs with semiconductor layer thicknesses from ∼15 to 50 nm exhibit similar electron mobilities (μ's) of 0.2-0.45 cm2 V(-1) s(-1). Reduction of the active film thickness led to decreased μ values; however, FETs with ∼2 and ∼5 nm thick P(NDI2OD-T2) films still exhibit substantial μ's of 0.01-0.02 and ∼10(-4) cm2 V(-1) s(-1), respectively. Interestingly, the lowest molecular weight sample (P-23, MW≈23 kg/mol, polydispersity index (PDI)=1.9) exhibited higher μ than the highest molecular weight sample (P-250, MW≈250 kg/mol, PDI=2.3) measured for thicker devices (15-50 nm). This is rather unusual behavior because typically charge carrier mobility increases with MW where improved grain-to-grain connectivity usually enhances transport events. We attribute this result to the high crystallinity of the lowest MW sample, as confirmed by differential scanning calorimetry and X-ray diffraction studies, which may (over)compensate for other effects.

For the fabrication of efficient photovoltaic devices and thin-film transistors, π-conjugated polymers with high molecular weight are desirable as they frequently show superior charge transport, morphological, and film-forming properties. Herein, we present an extremely fast tin-free method to polymerize a naphthalene diimide-dithiophenebased anion-radical monomer in the presence of Pd catalyst having bulky and electron-rich tritert-butylphosphine ligands (Pd/P t Bu 3 ). With this method, the corresponding semiconducting polymer, PNDIT2 (also known as P(NDI2OD-T2 or N2200) with a molecular weight in excess of 1000 kg/mol can be obtained quickly at room temperature and at rather low catalyst concentrations. In general, molecular weights of resulting polymer can be regulated by reaction conditions (e.g., catalyst concentration and reaction time). Besides high molecular weight PNDIT2 (e.g., with M N ∼ 350 kg/mol, Đ M =2.9), PNDIT2 with moderate molecular weight (e.g., M N ∼ 110 kg/mol, Đ M = 2.3) and low molecular weight (e.g., M W ∼ 12 kg/mol, Đ M = 1.9), can also be obtained. It was found that thus-prepared PNDIT2 exhibits field-effect electron mobilities of up to ∼0.31 cm 2 /(V s), similar to the Stille-derived N2200 control polymer (up to ∼0.33 cm 2 /(V s)). Preliminary studies demonstrated that Pd/P t Bu 3 catalyst is remarkably efficient in polymerizing of other anion-radical monomers, such as isoindigo-, and diketopyrrolopyrrole-based ones, although conventional Ni and Pd catalysts (e.g., Ni(dppp)Cl 2 , Ni(dppp)Cl 2 , Pd(PPh 3 ) 4 ) failed to polymerize these monomers.

The past two decades witnessed tremendous progress in the field of creation of different types of responsive materials. Cholesteric polymer networks present a very promising class of smart materials due to the combination of the unique optical properties of cholesteric mesophase and high mechanical properties of polymer networks. In the present work we demonstrate the possibility of fast and reversible photocontrol of the optical properties of cholesteric polymer networks. Several cholesteric photopolymerizable mixtures are prepared, and porous cholesteric network films with different helix pitches are produced by polymerization of these mixtures. An effective and simple method of the introduction of photochromic azobenzene-containing nematic mixture capable of isothermal photoinducing the nematic-isotropic phase transition into the porous polymer matrix is developed. It is found that cross-linking density and degree of polymer network filling with a photochromic nematic mixture strongly influence the photo-optical behavior of the obtained composite films. In particular, the densely cross-linked films are characterized by a decrease in selective light reflection bandwidth, whereas weakly cross-linked systems display two processes: the shift of selective light reflection peak and decrease of its width. It is noteworthy that the obtained cholesteric materials are shown to be very promising for the variety applications in optoelectronics and photonics.

In this paper we systematically investigated effect of separator morphology on the performance of Li-S batteries. We tested two kinds of commercially available non-woven fibrous separators made of polypropylene in conjunction with trilayer PP/PE/PP porous separator. Among the non-woven separators, the fibers of the separator of first kind are rough and more acidic than the fibers of the separator of second art, which are smooth. It was found that batteries with smooth separator demonstrate higher Coulombic efficiency, higher charging/discharging capacity and better cycling stability. We attribute better performance of batteries with smooth fibers of separators to lower acidity than that of rough fibers. We believe that negatively charged polysulfides are unable to adsorb on more acidic rough fibers and diffuse readily to lithium electrode. In contrast, polysulfides are able to adsorb on the surface of less acidic smooth fibers that reduces their polysulfides shuttle and rapid decay of battery capacity. Strategic deployment of non-woven Freudenberg and Celgard separator in combination leads to high active mass utilization, superior wettability, reduced short circuit tendency caused by dendritic growth and slower capacity decay.

Efficient, scalable energy storage systems such as lithium‐sulfur batteries have become a technological bottleneck for the growing energy demands in automotive sector. To realize the ultimate performance of such batteries, the effect of all structural components of the batteries has to be considered. Nowadays the effect of current collectors appears to be less explored in the battery research field. Therefore, this report draws attention to exploit different current collectors such as, copper, aluminum, platinum, and nickel. It is found that nickel has a profound effect on the performance of the lithium‐sulfur batteries by direct involvement in electrochemical reaction with soluble polysulfides leading to the formation of nickel sulfide. The formation of such unwanted species can be reduced dramatically by silane‐surface modification. Aluminum and platinum, on the other hand, have been found to be the most inert collector toward the cycle performance because of nonreactivity within the potential window.