Improving Performance of Dye-Sensitized Solar Cell by Multi-Emission Effect of Phosphors.

Generally, the N-719 dye, used in dye-sensitized solar cells (DSSCs), only absorbs visible light in the wavelength range from 400 to 700 nm. Consequently, most of the ultraviolet and infrared rays from the sun are not utilized by this dye. However, ultraviolet and infrared rays can be converted to visible light by upconversion luminescence. Such visible light can then be reabsorbed by the dye, allowing for a larger range of solar irradiation to be utilized in DSSCs. Phosphor (ZnGa2O4, Y2O3:Er(3+)), acting as a luminescence medium, was added to the TiO2 electrode of DSSCs, and owing to the effect of upconversion, it increased their photocurrent density and efficiency. Phosphor (ZnGa2O4, Y2O3:Er(3+)) co-doped TiO2 electrode cells showed better performance than phosphor-free cells. In fact, the highest efficiency observed for a DSSC containing five phosphor layers was 7.03% with a short-circuit current density (Jsc) of 15.62 mA/cm2, an open circuit voltage (Voc) of 0.661 V, and a fill factor (FF) of 68.17%.

An energy efficient distance-aware routing algorithm with multiple mobile sinks for wireless sensor networks.

Traffic patterns in wireless sensor networks (WSNs) usually follow a many-to-one model. Sensor nodes close to static sinks will deplete their limited energy more rapidly than other sensors, since they will have more data to forward during multihop transmission. This will cause network partition, isolated nodes and much shortened network lifetime. Thus, how to balance energy consumption for sensor nodes is an important research issue. In recent years, exploiting sink mobility technology in WSNs has attracted much research attention because it can not only improve energy efficiency, but prolong network lifetime. In this paper, we propose an energy efficient distance-aware routing algorithm with multiple mobile sink for WSNs, where sink nodes will move with a certain speed along the network boundary to collect monitored data. We study the influence of multiple mobile sink nodes on energy consumption and network lifetime, and we mainly focus on the selection of mobile sink node number and the selection of parking positions, as well as their impact on performance metrics above. We can see that both mobile sink node number and the selection of parking position have important influence on network performance. Simulation results show that our proposed routing algorithm has better performance than traditional routing ones in terms of energy consumption.