Abstract
The ternary sodium molybdenum borate glasses with extra-addition of sulfur element are prepared using the conventional melt quenching technique. The structural properties of these prepared glasses are investigated by XRD and FTIR spectroscopy. The XRD patterns confirm the amorphous nature and the absence of any crystallinity in the investigated glasses. The FTIR result shows that there is a conversion between the trigonal [BO3] to tetrahedral [BO4] units, depending on the amount of extra-added sulfur. This result can interpret the composition dependence of the electrical activation energy of the glasses. The study of electrical properties indicates that the investigated glasses are thermally activated in the temperature range of 360-340 K, due to the ionic conduction. The dependences of the optical bandgap and the Urbach energy on the sulfur content reveal the structural role of sulfur as a reducing agent. The most important feature of these glasses is that they exhibit the photoconductivity phenomena with high photosensitivity, which makes them suitable for applications of solar cells. The photoconductivity of the investigated glasses comes from the electron hopping between Mo5+ and Mo6+ ions, which can be motivated by addition of sulfur. Finally, the differential lifetime can be calculated using the transient photoconductivity measurements.