Abstract Inverted organic photovoltaic solar cells were fabricated with the configuration of FTO/TiO2/P3HT:PC61BM/MoO3/Ag. Besides, the influence of transport layers, titanium dioxide and molybdenum trioxide, on the performance of solar cells were investigated. These compounds showed excellent optical (around 80% for molybdenum trioxide and 95% for titanium dioxide), electrical (like charge carrier density of 3.3 x1015 cm-3 and 2.5 x1014 cm-3 for titanium and molybdenum, respectively) and structural (anatase and amorphous hexagonal phase for titanium and molybdenum, respectively) properties to be used as transport layers. Also the influence of the thickness of the electron transport layer is studied, as well as the thickness, temperature and heat treatment time of the active layer. The correct selection of TiO2’s thickness (70 nm) and active layer’s thickness (250 nm) and annealing (at 100 degrees for 8 minutes) can increase the power conversion efficiency. Moreover, the cell fabricated with transport layers and the best conditions found showed a maximum efficiency of 3.3%, which indicates that the titanium dioxide and molybdenum trioxide played a determining role in the solar cell performance.

Abstract Antimony doped tin oxide (ATO) thin films are deposited on corning glass substrate using the spray pyrolysis technique. The experimental parameters such as distance between the substrate and source (10-30 cm), substrate temperature (350-450°C) and atmospheres (Nitrogen and Forming gas) are varied to study their effect on the properties of ATO thin films. The ATO thin film annealed at 425°C exhibits the lowest electrical resistivity of 2.23×10-2 Ω-cm. Besides, the film annealed in the nitrogen atmosphere showed a less resistivity value of 9.06×10-3 (Ω-cm) than the forming gas atmosphere. The film doped with 3 at% of Sb revealed the highest figure of merit value of 11.45x10-2 Ω-1. The preferential orientation is observed at the (200) diffraction plane in all the cases from the structural studies. Furthermore, the intensity of the diffraction planes decreases as the temperature increases. The average transmittance of 75% is obtained for ATO thin films.

Abstract Bismuth (III) sulfide thin films are prepared on glass substrates by physical vapor deposition technique. Then, the films are annealed at different temperatures from 150 to 350°C with nitrogen and nitrogen-sulfur atmospheres, respectively. The effect of annealing temperature on the optoelectronic properties is investigated. The layers were characterized using ultraviolet-visible spectroscopy, XRD, Raman spectroscopy, EDS analysis and Hall effect. The film annealed at 250°C in a nitrogen-sulfur atmosphere exhibited the best condition with an initial thickness of 106 nm and band gap of 1.37 eV. Also, Bismuthinite phase was obtained, close to the stoichiometry with 59.95 and 40.05 at % for bismuth and sulfur, respectively. The charge carrier concentration of 6.9x1019 cm-3 with a n-type conductivity, the resistivity of 0.19 Ω-cm, and mobility of 0.44 cm2V-1s-1 are obtained.

Resumo Descreve-se Trichotrigona extranea, uma nova espécie de Meliponinae do Amazonas, Brasil. Estruturalmente, Trichotrigona apresenta afinidades com Frieseomelitta e Duckeola, porém se distingue de todos os Meliponinae pela presença de pêlos nos olhos, tíbia clavada com pêlos plumosos apenas na margem distal, pente não diferenciado e abdômen terminando em ponta.

SUMMARY Trichotrigona extranea a new Meliponine bee is described from Amazonas, Brazil. Structurally Trichotrigona is closely related to Frieseomelitta and Duckeola but can be easely distinghished by having hairy eyes, broadly clavate hind tibiae without plumose hairs on posterior border and very few ones on apical margin, an acute last tergum and by lacking tibial comb.