Correct determination of charge transfer state energy from luminescence spectra in organic solar cells.

Generation and recombination of electrons and holes in organic solar cells occurs via charge transfer states located at the donor/acceptor interface. The energy of these charge transfer states is a crucial factor for the attainable open-circuit voltage and its correct determination is thus of utmost importance for a detailed understanding of such devices. This work reports on drastic changes of electroluminescence spectra of bulk heterojunction organic solar cells upon variation of the absorber layer thickness.

Macroscopic Superlow Friction of Steel and Diamond-Like Carbon Lubricated with a Formanisotropic 1,3-Diketone.

Energy dissipation due to friction and wear is reducing the energy efficiency and reliability of mechanical systems. Thus, great efforts are being made to minimize friction for technical applications. In our present work, we investigate the tribological behavior of stainless steel 100Cr6 with a-C:H and a-C:H:Si coating lubricated with a surface-active formanisotropic 1,3-diketone.

Ultralow Friction of Steel Surfaces Using a 1,3-Diketone Lubricant in the Thin Film Lubrication Regime.

Ultralow friction (coefficient of friction μ ≈ 0.005) is observed when two steel surfaces are brought into sliding contact in the presence of a particular 1,3-diketone lubricant (1-(4-ethyl phenyl) nonane-1,3-dione). We investigate the friction process of such a system both experimentally and theoretically and show that the superlubricity is caused by a novel, unique mechanism: The formation of iron-1,3-diketonato complexes during frictional contact leads to a self-limiting, tribochemical polishing process while at the same time a self-assembled monolayer of the diketone is formed on the employed steel surfaces.