Law Matt, Greene Lori E, Radenovic Aleksandra, Kuykendall Tevye, Liphardt Jan, Yang Peidong
Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA.
J Phys Chem B. 2006 Nov 16;110(45):22652-63. doi: 10.1021/jp0648644.
We describe the construction and performance of dye-sensitized solar cells (DSCs) based on arrays of ZnO nanowires coated with thin shells of amorphous Al(2)O(3) or anatase TiO(2) by atomic layer deposition. We find that alumina shells of all thicknesses act as insulating barriers that improve cell open-circuit voltage (V(OC)) only at the expense of a larger decrease in short-circuit current density (J(SC)). However, titania shells 10-25 nm in thickness cause a dramatic increase in V(OC) and fill factor with little current falloff, resulting in a substantial improvement in overall conversion efficiency, up to 2.25% under 100 mW cm(-2) AM 1.5 simulated sunlight. The superior performance of the ZnO-TiO(2) core-shell nanowire cells is a result of a radial surface field within each nanowire that decreases the rate of recombination in these devices. In a related set of experiments, we have found that TiO(2) blocking layers deposited underneath the nanowire films yield cells with reduced efficiency, in contrast to the beneficial use of blocking layers in some TiO(2) nanoparticle cells. Raising the efficiency of our nanowire DSCs above 2.5% depends on achieving higher dye loadings through an increase in nanowire array surface area.
我们描述了基于通过原子层沉积涂覆有无定形Al₂O₃或锐钛矿TiO₂薄壳的ZnO纳米线阵列的染料敏化太阳能电池（DSC）的构建和性能。我们发现，所有厚度的氧化铝壳都充当绝缘势垒，仅以更大幅度降低短路电流密度（J(SC)）为代价来提高电池开路电压（V(OC)）。然而，厚度为10 - 25 nm的二氧化钛壳会使V(OC)和填充因子显著增加，而电流几乎没有下降，从而使整体转换效率大幅提高，在100 mW cm⁻² AM 1.5模拟太阳光下高达2.25%。ZnO - TiO₂核壳纳米线电池的优异性能是由于每个纳米线内的径向表面场降低了这些器件中的复合速率。在一组相关实验中，我们发现与在一些TiO₂纳米颗粒电池中有益地使用阻挡层相反，在纳米线薄膜下方沉积的TiO₂阻挡层会使电池效率降低。将我们的纳米线DSC效率提高到2.5%以上取决于通过增加纳米线阵列表面积来实现更高的染料负载量。
