Easily Attainable Phenothiazine-Based Polymers for Polymer Solar Cells: Advantage of Insertion of <i>S</i>,<i>S</i>-dioxides into its Polymer for Inverted Structure Solar Cells

Two donor– (D−) acceptor (A) type polymers based on a soluble chromophore of phenothiazine (PT) unit that is a tricyclic nitrogen–sulfur heterocycle, have been synthesized by introducing an electron-deficient benzothiadiazole (BT) building block copolymerized with either PT or phenothiazine-<i>S</i>,<i>S</i>-dioxide (PT-<i>SS</i>) unit as an oxidized form of PT. The resulting polymers, <b>PPTDTBT</b> and <b>PPTDTBT-</b><i><b>SS</b></i> are fully characterized by UV–vis absorption, electrochemical cyclic voltammetry, X-ray diffraction (XRD), and DFT theoretical calculations. We find that the maximum absorption of <b>PPTDTBT</b> is not only markedly red-shifted with respect to that of <b>PPTDTBT-</b><i><b>SS</b></i> but also its band gap as well as molecular energy levels are readily tuned by the insertion of <i>S</i>,<i>S</i>-dioxides into the polymer. The main interest is focused on the electronic applications of the two polymers in organic field-effect transistors (OFETs) as well as conventional and inverted polymeric solar cells (PSCs). <b>PPTDTBT</b> is a typical p-type polymer semiconductor for OFETs and conventional PSCs based on this polymer and PC₇₁BM show a power conversion efficiency (PCE) of 1.69%. In case of <b>PPTDTBT-</b><i><b>SS</b></i>, the devices characteristics result in: (i) 1 order of magnitude higher hole mobility (μ = 6.9 × 10^–4 cm² V^–1 s^–1) than that obtained with <b>PPTDTBT</b> and (ii) improved performance of the inverted PSCs (1.22%), compared to its conventional devices. Such positive features can be accounted for in terms of closer packing molecular characteristics owing either to the effects of dipolar intermolecular interactions orientated from the sulfonyl groups or the relatively high coplanarity of <b>PPTDTBT-</b><i><b>SS</b></i> backbone

Ambipolar Semiconducting Polymers with <i>π-</i>Spacer Linked Bis-Benzothiadiazole Blocks as Strong Accepting Units

Recognizing the importance of molecular coplanarity and with the aim of developing new, ideal strong acceptor-building units in semiconducting polymers for high-performance organic electronics, herein we present a simplified single-step synthesis of novel vinylene- and acetylene-linked bis-benzothiadiazole (<b>VBBT</b> and <b>ABBT</b>) monomers with enlarged planarity relative to a conventionally used acceptor, benzothiadiazole (BT). Along these lines, four polymers (<b>PDPP-VBBT</b>, <b>PDPP-ABBT</b>, <b>PIID-VBBT</b>, and <b>PIID-ABBT</b>) incorporating either <b>VBBT</b> or <b>ABBT</b> moieties are synthesized by copolymerizing with centro-symmetric ketopyrrole cores, such as diketopyrrolopyrrole (DPP) and isoindigo (IID), and their electronic, physical, and transistor properties are studied. These polymers show relatively balanced ambipolar transport, and <b>PDPP-VBBT</b> yields hole and electron mobilities as high as 0.32 and 0.13 cm² V^–1 s^–1, respectively. Interestingly, the acetylenic linkages lead to enhanced electron transportation in ketopyrrole-based polymers, showing a decreased threshold voltage and inverting voltage in the transistor and inverter devices, respectively. The IID-based BBT polymers exhibit the inversion of the dominant polarity depending on the type of unsaturated carbon bridge. Owing to their strong electron-accepting ability and their highly π-extended and planar structures, <b>VBBT</b> and <b>ABBT</b> monomers should be extended to the rational design of high-performance polymers in the field of organic electronics

Highs and lows of lambing time: Sheep farmers? perceptions of the first outbreak of schmallenberg disease in south west England on their well-being

The outbreak of a previously unknown and new disease in the United Kingdom, known as ‘Schmallenberg disease’, a disease associated with abortions, stillbirths and fetal deformities in naïve ewes, was reported for the first time in South West England during the 2012/13 early lambing season. Epidemiological studies confirmed that the Schmallenberg virus (SBV) had a severe negative impact upon animal welfare and the productivity of affected flocks. By contrast, there was a specific lack of research on the impact of SBV on sheep farmer well-being. This study aimed to improve our understanding of sheep farmers’ experiences of Schmallenberg disease, and the impact of the first outbreak on sheep farmer well-being during the 2012/13 early lambing season in South West England. Face-to-face, semi-structured interviews with six farmers with small flocks of pedigree and purebred sheep in South West England were conducted in 2013. The data were analysed via thematic analysis. The main themes regarding the impact of disease on farmer well-being included: (i) emotional highs and lows are part of a normal lambing season; (ii) negative emotions and memories associated with the Schmallenberg disease outbreak; and (iii) resilience and coping with the unexpected disease outbreak. These novel data present preliminary findings from a small number of sheep farmers, and indicate that for some farmers, an unexpected outbreak of a new and emerging disease for the first time during lambing, and dealing with high levels of dystocia, deformities and deaths in their animals, had a negative impact on their emotional well-being during the peak period of the sheep production cycle

A Thienoisoindigo-Naphthalene Polymer with Ultrahigh Mobility of 14.4 cm²/V·s That Substantially Exceeds Benchmark Values for Amorphous Silicon Semiconductors

By considering the qualitative benefits associated with solution rheology and mechanical properties of polymer semiconductors, it is expected that polymer-based electronic devices will soon enter our daily lives as indispensable elements in a myriad of flexible and ultra low-cost flat panel displays. Despite more than a decade of research focused on designing and synthesizing state-of-the-art polymer semiconductors for improving charge transport characteristics, the current mobility values are still not sufficient for many practical applications. The confident mobility in excess of ∼10 cm²/V·s is the most important requirement for enabling the realization of the aforementioned near-future products. We report on an easily attainable donor–acceptor (D–A) polymer semiconductor: poly­(thienoisoindigo-<i>alt</i>-naphthalene) (PTIIG-Np). An unprecedented mobility of 14.4 cm²/V·s, by using PTIIG-Np with a high-<i>k</i> gate dielectric poly­(vinylidenefluoride-trifluoroethylene) (P­(VDF-TrFE)), is achieved from a simple coating processing, which is of a magnitude that is very difficult to obtain with conventional TFTs by means of molecular engineering. This work, therefore, represents a major step toward truly viable plastic electronics