Effects of working pressure and power on photovoltaic and defect properties of magnetron sputtered Sb2Se3 thin-film solar cells.

Antimony selenide (${\text{Sb}_2}{\text{Se}_3}$Sb2Se3) is an emerging material with potential applications in photovoltaics, while magnetron sputtering is an important method in material growth. In this study, ${\text{Sb}_2}{\text{Se}_3}$Sb2Se3 thin films, prepared by the magnetron sputtering technique with varied working pressures and sputtering powers, were fabricated into solar cells with a structure of $\text{glass}/\text{ITO}/\text{CdS}/{\text{Sb}_2}{\text{Se}_3}/\text{Au}$glass/ITO/CdS/Sb2Se3/Au. The current density versus voltage measurements and x-ray diffraction were introduced to compare the photovoltaic and structural properties of the cell samples. Characterization and identification of the defects in ${\text{Sb}_2}{\text{Se}_3}$Sb2Se3 thin films were investigated by admittance measurements. The ${\text{Sb}_2}{\text{Se}_3}$Sb2Se3 cell samples prepared with appropriate sputtering power (about 60 W) or working pressure (about 0.4 Pa) were found to own better crystal qualities and lower defect densities, which may be the reason for better efficiency.

The role of stream water carbon dynamics and export in the carbon balance of a tropical seasonal rainforest, southwest China.

A two-year study (2009 ~ 2010) was carried out to investigate the dynamics of different carbon (C) forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN), southwest China. The seasonal volumetric weighted mean (VWM) concentrations of total inorganic C (TIC) and dissolved inorganic C (DIC) were higher, and particulate inorganic C (PIC) and organic C (POC) were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC) and dissolved organic C (DOC) were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT), only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC) export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha(-1) yr(-1), about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest.