The role of bathocuproine ͑BCP͒ buffer layer inserted between active layer and Al contact in photovoltaic cells based on phthalocyanine ͑Pc͒ and C 60 was investigated. Photoluminescence ͑PL͒ experiments show exciton quenching at the C 60 -Al interface to be strongly reduced by inserting BCP. Current-voltage characteristics of photovoltaic cells with planar geometry front electrode/ Pc/ C 60 / BCP/ Al show that BCP dramatically improves electron transport out of the C 60 film into the Al electrode. The tenfold increase in power conversion efficiency ͑͒ with BCP can mostly be attributed to the latter effect. BCP does not improve in photovoltaic cells with blend film geometry front electrode/Pc: C 60 / Al.

The authors report factors that limit the photovoltaic parameters of organic solar cells based on phtalocyanine:fullerene bulk heterojunction. They show that the device photovoltaic properties and their stability are strongly influenced by O2 impurities. Oxygen affects mostly the photoelectrical properties of the fullerene and the state of the interface between phtalocyanine and fullerene domains. The illumination of the devices, especially in the wavelength range <570nm, induces photodiffusion of the oxygen into fullerene material and promotes formation of O2-fullerene dipoles and additional recombination levels due to C–O reactions that accelerate the device degradation.

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This paper presents a case study of using distributed word representations, word2vec in particular, for improving performance of Named Entity Recognition for the eCommerce domain. We also demonstrate that distributed word representations trained on a smaller amount of in-domain data are more effective than word vectors trained on very large amount of out-of-domain data, and that their combination gives the best results.