Kalu, Constance , Idorenyin Markson , Enyenihi, Henry Johnson (2018). Determination of Refractivity Gradient and Modified Refractivity Gradient for Cross River State. International Journal of Sustainable Energy and Environmental Research, 7(2): 53-64. DOI: 10.18488/journal.13.2018.72.53.64
In this paper, determination of refractivity gradient and modified refractivity gradient for Cross River state was carried out. The year 2013 Radiosonde meteorological data from Nigerian Meteorological Agency (NIMET) was used. Refractivity, modified refractivity, refractivity gradient and modified refractivity gradient were computed. The results showed that in the year 2013, Cross River state had maximum modified refractivity gradient (dM/dz) of 114.9 (M -units/Km) and it occurred in December whereas the minimum modified refractivity gradient (dM/dz) on 81.9 (M–units/Km) and it occurred in October . Also, in the year 2013, the maximum refractivity gradient (dN/dz) was -42.1 (N-units/Km) and it occurred in December whereas the minimum refractivity gradient (dN/dz) was -75.1 (N-units/Km) and it occurred in October. The standard refractivity gradient of -39 N-units and standard modified refractivity gradient of 118 M-units occurred in December at altitude of 103 meters. In all the months the atmospheric condition was in the normal state except in the month of October where superrefraction occurred.
This study is one of very few studies which have investigated the modified refractivity gradient for Cross River state. Available related studies on Cross River State were mainly on refractivity gradient.
Efficiency Enhancement in Plasmonic Dye-Sensitized Solar Cell Employing High Performance TiO2 Photoanode Doped with Silver Nanoparticles
Nazia Nasr , Muhammad Hassan Sayyad , Hytham Elbohy , Qiquan Qiao (2018). Efficiency Enhancement in Plasmonic Dye-Sensitized Solar Cell Employing High Performance TiO2 Photoanode Doped with Silver Nanoparticles. International Journal of Sustainable Energy and Environmental Research, 7(2): 44-52. DOI: 10.18488/journal.13.2018.72.44.52
High performance TiO2 photoanodes undoped and doped with silver nanoparticels of size about 15 nm were fabricated. Employing these electrodes dye-sensitized solar cells (DSSCs) were fabricated using N719 dye as sensitizer and iodide-triodide as redox couple. Current-voltage measurements were performed under the illumination of 100 mW cm-2 (AM 1.5). The electrical parameters of the fabricated cells were extracted from the current-voltage data that include open-circuit voltage, short-circuit current, shunt resistance, series resistance, fill-factor, ideality factor and solar energy-to-electricity conversion efficiency. The comparison of parameters revealed improvement in both the photovoltaic and electrical parameters of the plasmonic cell. The conversion efficiency measured for the reference cell without Ag NPs in TiO2 was 7.43 %, whereas the efficiency of plasmonic device with TiO2:Ag NPs was 9.26 %, resulting an overall efficiency improvement of 23% with Ag NPs. The increased performance of the plasmonic DSSC can be assigned to the improvement of its photovoltaic and electrical parameters. The improved short-circuit photocurrent density appears to be boosted due the enhanced light harvesting capability of the photoanode caused by the localized surface plasmon resonance effect induced in Ag nanoparticles. While, the rise in Voc can be credited to the upward shift of Fermi level of TiO2 due to the dopping of Ag nanoparticles in TiO2 network.
This study is based on one of the few attempts on photoanode engineering employing plasmonic effect for developing higher efficiency DSSCs. The comparison with the existing data has revealed significant improvement in the photovoltaic and electrical properties of the plasmonic device. This study has reported that Ag nanoparticles hold a unique plasmonic effect employing which performance parameters of the DSSC are improved much greater as compared to other metallic nanoparticles.