Magnetic, Structural, and Electrical Properties of Si1−xMnx Single Crystals

We have investigated the magnetic and the electrical transport properties of Si 1-xMn x (x = 0.5 and 0.75) single crystals grown by using the vertical Bridgman method. The alloys with the Mn concentration x = 0.5 have weak ferromagnetic ordering around T C ≃30 K. However, Si 0.25Mn 0.75 alloys show weak ferromagnetic ordering at 70 K and antiferromagnetic ordering at 104 K, which is confirmed by magnetization, electrical transport, and neutron diffraction studies. The conductivities appear to be n-type for samples with x = 0.5 and p-type for x = 0.75.ope

D–A–D-type narrow-bandgap small-molecule photovoltaic donors: pre-synthesis virtual screening using density functional theory

International audienceA new series of D–A–D-type small-molecule photovoltaic donors are designed and virtually screened before synthesis using time-dependent density functional theory calculations carefully validated against various polymeric and molecular donors. In this series of new design, benzodithiophene is kept as D to achieve the optimum highest-occupied molecular orbital energy level, while thienopyrroledione is initially chosen as A but later replaced by difluorinated benzodiathiazole or its selenide derivative to achieve the optimum band gap. The D–A–D core is end-capped by pyridone units which could not only enhance their self-assembly via hydrogen bonds but also play a role as an acceptor (A′) to form an extended A′–D–A–D–A′ small-molecule donor

Direct Observation of Confinement Effects of Semiconducting Polymers in Polymer Blend Electronic Systems

Abstract The advent of special types of polymeric semiconductors, known as “polymer blends,” presents new opportunities for the development of next‐generation electronics based on these semiconductors' versatile functionalities in device applications. Although these polymer blends contain semiconducting polymers (SPs) mixed with a considerably high content of insulating polymers, few of these blends unexpectedly yield much higher charge carrier mobilities than those of pure SPs. However, the origin of such an enhancement has remained unclear owing to a lack of cases exhibiting definite improvements in charge carrier mobility, and the limited knowledge concerning the underlying mechanism thereof. In this study, the morphological changes and internal nanostructures of polymer blends based on various SP types with different intermolecular interactions in an insulating polystyrene matrix are investigated. Through this investigation, the physical confinement of donor–acceptor type SP chains in a continuous nanoscale network structure surrounded by polystyrenes is shown to induce structural ordering with more straight edge‐on stacked SP chains. Hereby, high‐performance and transparent organic field‐effect transistors with a hole mobility of ≈5.4 cm2 V–1 s–1 and an average transmittance exceeding 72% in the visible range are achieved