Page - 163 - in Photovoltaic Materials and Electronic Devices

EfficiencyEnhancementofDye-Sensitized SolarCells’PerformancewithZnO NanorodsGrownbyLow-Temperature HydrothermalReaction Fang-ILai, Jui-FuYangandShou-YiKuo Abstract: In this study, aligned zinc oxide (ZnO) nanorods (NRs) with various lengths (1.5–5µm) were deposited on ZnO:Al (AZO)-coated glass substrates by usingasolutionphasedepositionmethod; theseNRswerepreparedforapplication as working electrodes to increase the photovoltaic conversion efficiency of solar cells. The results were observed in detail by using X-ray diffraction, field-emission scanning electron microscopy, UV-visible spectrophotometry, electrochemical impedance spectroscopy, incident photo-to-current conversion efficiency, and solar simulation. The results indicated that when the lengths of the ZnO NRs increased, theadsorptionofD-719dyesthroughtheZnONRsincreasedalongwithenhancing the short-circuit photocurrent and open-circuit voltage of the cell. An optimal power conversion efficiency of 0.64% was obtained in a dye-sensitized solar cell (DSSC) containing the ZnO NR with a length of 5µm. The objective of this study wasto facilitate thedevelopmentofaZnO-basedDSSC. Reprinted from Materials. Cite as: Lai, F.-I.; Yang, J.-F.; Kuo, S.-Y. Efficiency Enhancement of Dye-Sensitized Solar Cells’ Performance with ZnO Nanorods GrownbyLow-TemperatureHydrothermalReaction.Materials2015,8, 8860–8867. 1. Introduction Dye-sensitized solar cells (DSSC) belong to the third generation of solar cells. Due their low-cost materials and low-cost technologies, they are the promising replacement for conventional silicon-based solar cells [1]. The highest single-cell conversion efficiency of 13% is comparable to the Si cells [2]. Generally, TiO2 nanoparticlefilmscoatedontofluorine-dopedtinoxide(FTO)layersaremadeasthe photoelectrodeinDSSCsbecauseof theirsuitablechemicalaffinityandsurfacearea for dye adsorption as well as their proper energy band promising charge transfer between the electrolytes and dye [3,4]. However, the one problem of DSSCs is that notallofthephotogeneratedelectronscanarriveatthecollectingelectrode,because electron transport within the nanoparticle network takes place via a series of hops to adjacent particles, and the energy damage that occurs during charge transport processes results in conversion efficiency. This trapping process results in the transport becoming slow, and an increase in scattering, which greatly increases the 163