π-Conjugated polymers and molecules enabling small photon energy loss simultaneously with high efficiency in organic photovoltaics

Organic photovoltaics (OPVs) are a topic of significant research interest in the field of renewable energy as well as organic electronics. The crucial issue in OPVs is the improvement of the power conversion efficiency (PCE). In addressing this issue, one of the most important factors is the photon energy loss (Eloss), which is defined as the difference between the bandgap of the materials and the energy corresponding to the open-circuit voltage. Typically, the Eloss for OPVs is considerably larger than that for inorganic and perovskite photovoltaics, which has prevented OPVs from generating larger photovoltages. In parallel, reducing the Eloss for OPVs causes a loss of driving-force energy for charge generation, which is detrimental to the generation of photocurrent. Thus, OPVs have been facing a trade-off between photocurrent and photovoltage. However, a number of recently developed π-conjugated materials for use as p-type and n-type organic semiconductors have been shown to enable small Eloss values that are close to those for inorganic systems, simultaneously with efficient charge generation. Here, we summarize recent progress in π-conjugated polymers and molecules that enable small Eloss and high PCE at the same time. We hope that this review will be of help to chemists and materials scientists who are involved in the design of materials and blends with an eye toward highly efficient OPVs

Relationship between watershed environments and growth of coastal diatoms

Effect of watershed environments on river water quality and the subsequent influence of water quality on the growth of diatoms in coastal seawater were studied. Land use in the upper and lower site of the Ohkawa River (O-up and O-low) and the upper site of the Nanakita River (N-up) were dominated by forestry, whereas the lower site of the Nanakita River (N-low) was characterized by urbanization. Seasonal changes in nutrients in the Ohkawa and Nanakita Rivers suggested that the concentrations of NH_4-N, NO_3-N, PO_4-P and acid extractable-Fe were influenced by human activities, while Si concentration reflected geological conditions. The average concentrations of fulvic acid-like Fe (FA-Fe), closely associated with the growth of coastal diatoms, were 1 and 16μgL^ at the O-up and O-low sites, respectively, while those of the Nanakita River were 5μgL^ (N-up) and 53μgL^ (N-low). For each river, FA-Fe concentrations of the lower sites were much higher than the upper sites. Moreover, the concentration of FA-Fe at N-low was much higher than at O-low. Therefore, it was concluded that FA-Fe originates not only from forest vegetation but also from urban activity. The growth of the Skeletonema, a typical diatom of coastal waters, was stimulated by the addition of O-low river water compared to addition of O-up, reflecting the FA-Fe content. Diatom growth stimulation with the addition of lower river water was much more prominent in the Nanakita River, whose watershed is characterized by runoff from Sendai city.Original Pape

有機太陽電池の高効率化に向けたチアゾロチアゾール系半導体ポリマーの開発

広島大学(Hiroshima University)博士(工学)Doctor of Engineeringdoctora

Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV pppp collider

Within the theory of supersymmetry, the lightest neutralino is a dark matter candidate and is often assumed to be the lightest supersymmetric particle (LSP) as well. If the neutral wino or higgsino is dark matter, the upper limit of the LSP mass is determined by the observed relic density of dark matter. If the LSP is a nearly-pure neutral state of the wino or higgsino, the lightest chargino state is expected to have a significant lifetime due to a tiny mass difference between the LSP and the chargino. This article presents discovery potential of the 100 TeV future circular hadron collider (FCC) for the wino and higgsino dark matter using a disappearing-track signature. The search strategy to extend the discovery reach to the thermal limits of wino/higgsino dark matter is discussed with detailed studies on the background rate and the reference design of the FCC-hadron detector under possible running scenarios of the FCC-hadron machine. A proposal of modifying the detector layout and several ideas to improve the sensitivity further are also discussed.Comment: 10 pages, 7 figures, 4 table