Improvements in electrodeposited Cu2O as the wide bandgap cell for a tandem solar architecture

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.Cuprous oxide is a well-known wide-bandgap material with Egap commonly reported around 2.0 eV, but with some reports ranging from 1.7eV to 2.5eV. With a bandgap around 2.0 eV it is a great candidate for the top cell of a stack tandem architecture paired with a bottom silicon cell. However the actual reported efficiencies of single junction devices are usually much lower than would be expected, probably rooted in possible defects, nonstoichiometry or microstructural flaws. We report on electrodeposited thin films and their growth modes under different conditions. Microstructural improvements have been made using seeding layers before electrodeposition; these are mainly focused on growing columnar shaped grains. Cu2O that has been electrodeposited has a flowering or dendritic microstructure. When the electrodeposition is seeded appropriately the dendrite arms from the flower no longer grow resulting in nicely faceted grains and a columnar shape. This well-crystallized columnar structure is meant to increase the hole collection length by avoiding recombination at grain boundary defects as a means of increasing the efficiency. Seeding the growth on the films has resulted in Cu2O films that are more controllable in the electrodeposition process, with a more consistent grain orientation. SEM and XRD analysis were performed to show these results.cf201

Tumor immunosurveillance in human cancers

Until now, the anatomic extent of tumor (TNM classification) has been by far the most important factor to predict the prognosis of colorectal cancer patients. However, in recent years, data collected from large cohorts of human cancers demonstrated that the immune contexture of the primary tumors is an essential prognostic factor for patients’ disease-free and overall survival. Tumoral and immunological markers predicted by systems biology methods are involved in the shaping of an efficient immune reaction and can serve as targets for novel therapeutic approaches. Global analysis of tumor microenvironment showed that the nature, the functional orientation, the density, and the location of adaptive immune cells within distinct tumor regions influence the risk of relapse events. The density and the immune cell location within the tumor have a prognostic value that is superior to the TNM classification, and tumor invasion is statistically dependent on the host-immune reaction. Thus, the strength of the immune reaction could advance our understanding of cancer evolution and have important consequences in clinical practice