In this paper, we report the significant effects of dye loading conditions on the overall light conversion efficiency of zinc oxide (ZnO) film electrodes in dye-sensitized solar cells. A comparison of the ZnO film electrodes was also made with TiO 2 film electrodes prepared with similar dye loading conditions. It was found that using a higher and lower dye concentration requires a shorter and longer immersion time, respectively, for optimal sensitization of ZnO to obtain maximum efficiencies. A similar trend was found for the TiO 2 film electrode as well; however, smaller differences in the overall light conversion efficiencies were observed with varying dye concentration and immersion time. It was found that the chemical stability was an issue for the ZnO film electrodes but was not pertinent for the TiO 2 film electrodes. The film quality and structure of the ZnO film differed after prolonged immersion in high dye concentration, where the formation of N3 dye and Zn 2+ aggregates and/or the deterioration of the ZnO colloidal spheres and nanoparticles on the surface may have occurred. On the other hand, the film quality and structure of the TiO 2 film was not appreciably affected by prolonged immersion in high dye concentration, where the nanoparticle structure was not affected.

Since the advent of dye-sensitized solar cells (DSCs), which have achieved $11% of power conversion efficiency (PCE) in TiO 2 -based photoelectrodes, a lot of efforts have been devoted to make low-cost, light-weight, high-performance photovoltaic devices. [1][2][3] Nanostructured metal oxides are one of key factors in determining the PCE of DSCs, because the nanostructured networks provide a huge surface area to accommodate a large quantity of dye molecules that relate to the light harvesting of a photoelectrode in DSCs.ZnO is a good alternative of TiO 2 because it has a similar band gap but higher electron mobility than TiO 2 . [4][5][6][7] The mobility of ZnO is about 115-155 cm 2 V À1 s À1, much higher than that of TiO 2 , $10 À5 cm 2 V À1 s À1. Recently, DSCs with photoelectrodes made of submicrometer-sized aggregates of ZnO nanocrystallites demonstrated a PCE of 5.4% due to much enhanced light scattering without compromising the surface area for dye molecule adsorption. [8][9][10] A porous structured ZnO aggregates of nanocrystallites were thought to be helpful to retain their high surface area. Although this PCE is still lower than that of TiO 2 DSCs, it doubled the PCE of ZnO nanocrystallite DSCs.Atomic layer deposition (ALD) has been used to introduce extremely thin and conformal coating due to its unique self-limiting nature and low growth temperature; lots of semiconductor materials like TiO 2 , ZnO, SnO, and Al 2 O 3 can be grown by ALD. [11][12][13] In this study, we utilized ALD to deposit ultrathin TiO 2 layer on the porous structure of ZnO aggregates and demonstrated much enhanced PCE of ZnO DSC with photoelectrodes made of submicrometer-sized aggregates of ZnO nanocrystallites.As illustrated schematically in Figure 1a-c, TiO 2 ultrathin layer deposited by ALD would form a complete and conformal coverage on the surface and even inside pores of ZnO that would otherwise be exposed to dye electrolyte during the dye loading. Consequently, all the dye molecules would adsorb onto the surface of TiO 2 coating. Such an ultrathin and conformal ALD coating would not change the morphology the underline ZnO structures as shown in Figure 1e and 1f. The coating of TiO 2 layer on the surface of ZnO by ALD is presumably so thin that would not affect any detectable change in the morphology by means of scanning electron microscopy (SEM). Brunauer Emmett Teller (BET) results demonstrate that micropores inside each aggregate still remain after ALD, indicating that the porous structure of ZnO is preserved. As shown in Table 1, the slight decrease in the size and volume of the micropore was observed due to the introduction of ALD-TiO 2 layer. In addition, the connections between adjacent ZnO nanocrystallites would retain to ensure a favorable electron motion through ZnO (as suggested in Fig. 1d). Such structure would improve the surface stability with enhanced dye loading on the ZnO surface, while retains the advantage of high electron mobility in ZnO.It is reported that the growth rate of TiO 2 at the substrate tempera...

We developed decision rule sets for Lipid Data Analyzer (LDA; http://genome.tugraz.at/lda2), enabling automated and reliable annotation of lipid species and their molecular structures in high-throughput data from chromatography-coupled tandem mass spectrometry. Platform independence was proven in various mass spectrometric experiments, comprising low- and high-resolution instruments and several collision energies. We propose that this independence and the capability to identify novel lipid molecular species render current state-of-the-art lipid libraries now obsolete.

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Photoelectrode made of nanocable structure of ZnO nanorods (NR) coated with TiO(2) nanosheets (NSs) was investigated for CdS/CdSe quantum dot co-sensitized solar cells. ZnO NRs prepared solution reaction at 60 °C served as the backbone for direct electron transport in view of the single crystallinity of the ZnO NRs and the high electron mobility of ZnO semiconductor. Anatase TiO(2) NSs with the thickness of ∼10 nm and the length of ∼100 nm were assembled onto the surface of ZnO NRs via a solvothermal method. It was found that the thin shell of TiO(2) might have remarkable influence on the quantum dot sensitized solar cells (QDSCs) through (a) increasing the surface area of ZnO NRs to allow for adsorbing more quantum dots (QDs), which led to high short current density, (b) forming an energy barrier that hindered the electrons in the ZnO from being back to the electrolyte and QDs, and thus, reduced the charge recombination rate, resulting in prolonged electron lifetime and enhanced open voltage. In comparison with the case of ZnO NRs, the short-circuit current density, open-circuit voltage, fill factor and charge recombination resistance of ZnO/TiO(2) nanocable photoelectrode increase by 3%, 44%, 48% and 220%, respectively. As a result, a power conversion efficiency of 2.7% of QDSCs with core-shell structural nanocable photoelectrode has been obtained, which is as much as 230% of that of 1.2% obtained for ZnO NR photoelectrode.