In vacuo XPS investigation of Cu In,Ga Se2 surface after RbF post deposition treatment

Latest record efficiencies of Cu In,Ga Se2 CIGSe solar cells were achieved by means of a rubidium fluoride RbF post deposition treatment PDT . To understand the effect of the RbF PDT on the surface chemistry of CIGSe and its interaction with sodium that is generally present in the CIGSe absorber, we performed an X ray photoelectron spectroscopy XPS study on CIGSe thin films as deposited by a three stage co evaporation process and after the consecutive RbF PDT. The sample transfer from the deposition to the XPS analysis chamber was performed via an ultra high vacuum transfer system. This allows to minimize air exposure, avoiding oxide formation on the CIGSe surface, especially for alkali treated absorbers. Beside an expected reduction of Cu and Ga content at the surface of RbF treated CIGSe films, we find that Rb penetrates the CIGSe and, contrary to fluorine, it is not completely removed by subsequent ammonia etching. The remaining Rb contribution at 110.0 amp; 8239;eV binding energy, which appears after the RbF PDT is similar to the one detected on a co evaporated RbInSe2 reference sample and together with a new Se 3d contribution may hence belong to an Rb In Se secondary phase on the CIGSe surface. In addition, Na is driven towards the surface of the CIGSe absorber as a direct result of the RbF PDT. This proves the ion exchange mechanism in the absence of moisture and air oxygen between heavy Rb atoms incorporated via PDT and lighter Na atoms supplied by the glass substrate. A remaining XPS signal of Na 1 amp; 8239;s is observed after etching the vacuum transferred RbF CIGSe sample, indicating that Rb and or F are not as much a driving force for Na as oxygen usually i

CD20-targeting immunotherapy promotes cellular senescence in B-cell lymphoma

The CD20-targeting monoclonal antibody Rituximab is an established component of immunochemotherapeutic regimens against B-cell lymphomas, where its co-administration with conventional anti-cancer agents has significantly improved long-term outcome. However, the cellular mechanisms by which Rituximab exerts its anti-lymphoma activity are only partially understood. We show here that Rituximab induces typical features of cellular senescence, a long-term growth arrest of viable cells with distinct biological properties, in established B-cell lymphoma cell lines as well as primary transformed B-cells. In addition, Rituximab-based immunotherapy sensitized lymphoma cells to senescence induction by the chemotherapeutic compound Adriamycin (a.k.a. Doxorubicin), and, to a lesser extent, by the antimicrotubule agent Vincristine. Anti-CD20 treatment further enhanced secretion of senescence-associated cytokines, and augmented the DNA damage response (DDR) signaling cascade triggered by Adriamycin. As the underlying pro-senescence mechanism, we found intracellular reactive oxygen species (ROS) levels to be elevated in response to Rituximab, and, in turn, the ROS scavenger N-acetylcysteine (NAC) to largely abrogate Rituximab-mediated senescence. Our results, further supported by gene set enrichment analyses in a clinical data set of chronic lymphocytic leukemia patient samples exposed to a Rituximab-containing treatment regimen, provide important mechanistic insights into the biological complexity of anti-CD20-evoked tumor responses, and unveil cellular senescence as a hitherto unrecognized effector principle of the antibody component in lymphoma immunochemotherapy

Cu In,Ga Se2 surface treatment with Na and NaF A combined photoelectron spectroscopy and surface photovoltage study in ultra high vacuum

Either metallic Na or NaF were deposited onto Cu In,Ga Se2 surfaces and studied by photoelectron spectroscopy and surface photovoltage spectroscopy without breaking the ultra high vacuum. The deposition of elemental Na at room temperature led to the formation of an intermediate Cu and Ga rich layer at the CIGSe surface, whereas for NaF the composition of the CIGSe surface remained unchanged. A metal like surface induced by an inverted near surface region with a reduced number of defect states was formed after the deposition of Na. Under the chosen experimental conditions, the near surface layer was independent on the amount of Na and stable in time. In contrast, the usage of NaF weakened the inversion and led to an increased band bending compared to the untreated CIGSe sample. The SPV signals decreased with proceeding time after the deposition of NaF

Effects of KF and RbF post deposition treatments on the growth of the CdS buffer layer on CIGS thin films a comparative study

In this contribution we are analyzing and comparing the impact of two different alkali fluorine post deposition treatments KF and RbF on the growth of chemical bath deposited CdS buffer layers on Cu In, Ga Se2 absorber layers for thin film solar cells. By combining Raman scattering, scanning electron microscopy, current voltage analysis and measurements of the internal quantum efficiency we provide a comprehensive picture of this issue on the material and device level. We find that both PDTs lead to a better CdS coverage of the surface of the CIGS, which leads to an improved junction quality at early growth stages compared to untreated devices. Furthermore the growth rate of the CdS is enhanced on KF treated absorber layers while it is decreased on those treated with RbF compared to the reference . This leads to a more stable behavior of RbF treated devices after longer duration of the CdS deposition, while the KF treated devices suffer from reduced fill factor and open circuit voltage. Furthermore we show that not only both PDTs but also the growth of the CdS lead to a reduction of the amount of the so called ordered defect compound, which is initially present at the surface of our absorber layers. This behavior indicates either the formation of CdCu anti sites or of a secondary phase at the interfac