Synthesis and application of poly(fluorene-alt-naphthalene diimide) as an n-type polymer for all-polymer solar cells

A new alternating copolymer of fluorene and naphthalene diimide, PF-NDI, was synthesized and characterized. The highest power conversion efficiency of all-polymer solar cells based on P3HT:PF-NDI reached 1.63% with a relatively high fill factor of 0.66 by using 1,8-diiodooctane as a solvent additive to optimize the mixing morphology.     

Structure-odor relationships of α-santalol derivatives with modified side chains

(Z)-α-Santalol, which has a unique woody odor, is a main constituent of sandalwood essential oil. We investigated the structure-odor relationship of (Z)-α-santalol and its derivatives, focusing on the relationship between the structure of the side chain and the odor of the compounds. Various α-santalol derivatives (aldehydes, formates, and acetates) were synthesized from (Z)- and (E)-α-santalol, which were prepared from (+)-3-bromocamphor through modifications of a reported synthetic route. The Z- and E-isomers of α-santalols have different double-bond configurations in the side chain. Analogues with saturated side chains were also prepared from the corresponding α-santalols, and the odors of the all the prepared compounds were evaluated. We found that the odors of the Z-isomers (woody) were similar to those of the corresponding saturated compounds, but clearly different from the odors of the corresponding E-isomers (odorless, fresh, or fatty). These results indicate that the relative configuration of the side chain with respect to the santalane frame plays an important role in the odor of α-santalol. E-configuration in the side chain eliminates the woody odor character of α-santalol and its examined derivatives, whereas the Z-configuration or saturation of the carbon side chain does not.     

Soft-x-ray harmonic comb from relativistic electron spikes

We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving μJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.