The Effect of Organic and Metal Oxide Interfacial layers on the Performance of Inverted Organic Photovoltaics

We study the origin of the improvement of the power conversion efficiency (PCE) of inverted organic solar cells when an interfacial insulating organic layer of polyoxyethylene tridecyl ether (PTE) is introduced between the indium tin oxide (ITO) bottom electrode and the TiO_x interfacial layer. XPS and UPS measurements are used to investigate the energy level alignment at the interfaces within the ITO/TiO_x and ITO/PTE/TiO_x structures and to identify any effects due to chemical interaction and interfacial dipoles. Scanning electron microscopy studies show that the surface structure of the TiO_x layer is affected, when it is coated on top of the PTE layer. Surface contact angle measurements show that the incorporated interfacial layer of PTE is more hydrophilic than ITO and thus PTE modified TiO_x becomes more hydrophilic. This, in combination with the surface gaps of the PTE interfacial layer, is likely to lead to changed wetting and hydrolysis properties of TiO_x when coated on ITO/PTE than on ITO alone. The different TiO_x layer quality is reflected in improved electron selectivity, leading to enhanced fill factor, reduced parasitic resistance effects and higher power conversion efficiency for inverted solar cells with a PTE interfacial layer between ITO and TiO_x.     

Woodland history of northern Greece from the mid Holocene to recent time based on evidence from peat pollen profiles

The woodland history of the northern mountainous parts of Greece is considered in the context of pollen profiles from bogs in Rhodopes, Lailias-Vrontou, Paiko, Voras and Pieria. In the time period covered by these diagrams (only those from Voras and Lailias extend back to the 7th millennium B.P.) the overall trends in the woodland history at the particular sites are comparable but there are also substantial differences that are attributed to the effects of human influence which varied in time, intensify and extent. The earlier phase, which corresponds to the Atlantic period of Firbas, is characterized by mixed deciduous woodlands with Quercus or Tilia the main components. This is followed by the phase (Subboreal) in which coniferous woodlands, which consisted of Abies and Pinus, dominated. In this time, Fagus gradually expanded. In the final phase (Subatlantic), Abies becomes more or less extinct and Fagus has a dominant role. These developments broadly correspond with those recorded in pollen profiles from Central Europe.     

Cloning and expression of the uracil–DNA glycosylase inhibitor (UGI) from bacteriophage PBS-1 and crystallization of a uracil–DNA glycosylase–UGI complex

The uracil-DNA glycosylase inhibitory protein (UGI) from the bacterio-phage PBS-l has been cloned and overexpressed. The nucleotide sequence is identical to that for the previously described PBS-2 inhibitor. The recombinant PBS-l UGI inhibits the uracil-DNA glycosylase from herpes simplex virus type-l (HSV-l UDGase), and a complex between the HSV-l UDGase and PBS-l UGI has been crystallized. The crystals have unit cell dimensions a = 143.21 Å, c = 40.78 Å and are in a polar hexagonal space group. There is a single complex in the asymmetric unit with a solvent content of 62% by volume and the crystals diffract to 2.5Å on a synchrotron radiation source. © 1995 Wiley-Liss, Inc.