For an increased lifetime of polymer:fullerene bulk heterojunction (BHJ) solar cells, an understanding of the chemical and morphological degradation phenomena taking place under operational conditions is crucial. Phase separation between polymer and fullerene induced by thermal stress has been pointed out as a major issue to overcome. While often the effect of thermal stress on the morphology of polymer:fullerene BHJ is investigated in the darkness, here we observe that light exposure slows down fullerene crystallization and phase separation induced at elevated temperatures. The observed photo‐stabilizing effect on active layer morphology is quite independent on the polymer and is attributed to light‐induced dimerization of the fullerene. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1209–1214

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Nanocrystalline diamond (NCD) thin films were produced by chemical vapor deposition (CVD) and doped by the addition of phosphine to the gas mixture. The characterization of the films focused on probing the incorporation and distribution of the phosphorus (P) dopants. Electron microscopy evaluated the overall film morphology and revealed the interior structure of the nanosized grains. The homogeneous films with distinct diamond grains featured a notably low sp2:sp3‐ratio as confirmed by Raman spectroscopy. High resolution spectroscopy methods demonstrated a homogeneous P‐incorporation, both in‐depth and in‐plane. The P concentration in the films was determined to be in the order of 1019 cm–3 with a significant fraction integrated at substitutional donor sites. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

The surface of polycrystalline aluminum nitride (AlN) thin films is exposed to different gas discharge plasmas (N2, O2, and CF4) followed by a water-based colloidal seeding of ultra-dispersed nanodiamond particles. Fluorination of the AlN surface enhances the seeding density, whereas the oxidized surface does not yield any nucleation sites. In the former case, the seeding density improves by almost three orders of magnitude as compared to the untreated and N2 pretreated samples, and allows to grow pinhole-free nanocrystalline diamond film on AlN. Finally, we demonstrate a route towards selective diamond growth on AlN thin films by employing CF4 plasma pretreatment together with photolithography.

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