Cu 9 S 5 (digenite) is a p-type semiconductor with excellent electrical conductivity, high mobility of copper ions, and high work function. When used as the back electrode of CdTe solar cells, a high power conversion efficiency (PCE) is obtained. Density functional theory (DFT) method was used to study the structural and electronic properties of Cu 9 S 5 in this work. From the calculated band structures, we find that the Fermi level of the Cu 9 S 5 slightly crosses the valence band by about 0.08 eV below the valence band maximum (VBM), indicating a high hole concentration and potential high electrical conductivity as a p-type semiconductor. It is also found that the crystal structure of Cu 9 S 5 remained stable with a few Cu atoms diffused away, which introduces a p-type doping effect. Finally, we give a quantitative discussion on why CdTe solar cells with Cu 9 S 5 as the back electrode shows the high PCE.

Time-resolved photoluminescence (PL) spectroscopy has been performed at 18 K on excitonic-related emissions in an unintentionally doped hexagonal GaN epitaxial layer grown by two-flow metalorganic chemical vapor deposition (TF-MOCVD). Under low excitation condition, radiative recombination of A free exciton (EXA: 3.4921 eV) and neutral shallow-acceptor bound exciton [(A0s,X): 3.4805 eV] dominated the spectrum. Decay time of (A0s,X) emission is relatively long (585 ps) indicating a small number of non-radiative centers in the layer. At higher excitation densities, new PL peak appeared at 3.4864 eV and grew superlinearly with excitation densities. These features, combined with their transient behavior, suggest that this new emission band is due to the biexciton recombination.

CdTe is widely applied in thin film solar cells as a p-type layer, which is usually in contact with a metal back electrode.

This is a case report of a 24-year-old man who presented with increased pain and firm swelling of the right foot after a minor twisting injury. Radiography, computed tomography (CT) and magnetic resonance imaging (MRI) findings showed ancillary information that was helpful for surgical treatment. The final diagnosis was confirmed as chondroblastoma of the navicular bone based on the pathology report. The navicularbone is a very rare site in the foot, where we should pay attention to chondroblastoma.

Concentration and origin of defect states in p-type nitrogen-doped ZnSe (p-ZnSe:N) grown by metalorganic vapor-phase epitaxy (MOVPE) are discussed by means of timeresolved photoluminescence and deep level transient spectroscopy. Thermal annealing, which is a useful tool for realizing p-type conductivity, results in deep defect states which seem to be associated with Zn vacancies and with nitrogen acceptors. By lowering the annealing temperature, the trap concentrations can be successfully reduced without seriously sacrificing the acceptor activation efficiency, although further reduction of Zn vacancies is pointed out as a remaining requirement for the improvement of quality of MOVPE-grown p-type layers.

Based on the deficiency of traditional acidification or acid pressure technology in the development of carbonate oil and gas resources, a microcapsule which wraps hydrochloric acid and can be released through temperature control was prepared by using microcapsule technology. The microcapsules were prepared with polyurethane prepolymer (PUA) and 1,6-hexadiol diacrylate (HDDA) polymer as wall material and hydrochloric acid as core material by two emulsification and photocatalysis methods. Its parcel rate is 61.9%. Fourier transform infrared spectroscopy characterization confirmed the successful photopolymerization of PUA prepolymer and HDDA in a strong acid environment. The microscopic morphology analysis of electron microscope showed that the microcapsule was regular and uniform spherical with smooth and dense surface. The particle size analysis showed that the microcapsules were mainly distributed between 40 and 300 μm, and the average particle size was 114.02 μm.The glass temperature of microcapsule wall material was 97 C by DSC method. The release rate of microcapsules was accelerated with the increase of release temperature. The cumulative release rate of acid solution of microcapsules for 3 h reached 28.4%, and the final release rate of microcapsules for 12 h reached 90.7% under 100 C. In addition, the release of microcapsules is less affected by the formation salinity. At 90 C, the maximum release rate of 7.5 g/L CaCL 2 was 49.1%, lower than that of 59.4% in pure water, showing the good salt resistance of the wall materials of microcapsules.

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