摘要
Two-dimensional(2D) ZnO nanosheet arrays were prepared via vanadium(V)-doping assisted hydrothermal method, and then the nanosheet was successfully converted to a nanorod-on-nanosheet ZnO hierarchical structure by treating with Na_2S solution and subsequent hydrothermal reaction. Hierarchical films with different nanorod growth time(1–8h) were prepared and their photovoltaic properties were also investigated after electrodeposition of CdSe quantum dots. For the hierarchical nanorod-on-nanosheet ZnO films, increasing the ZnO nanorod growth time can enormously enlarge the length of branched nanorods and light-scattering ability, resulting in better light-harvesting efficiency and higher photo-generated electron concentration, which leads to higher short-circuit current density(J_(sc)) and open-circuit voltage(V_(oc)). However,further increasing nanorod growth time to 8h leads to the over-dense coverage of nanorods, which is harmful for light-harvesting efficiency and leads to severe electron recombination, eventually diminishes the power conversion efficiency(PCE). With the optimized nanorod modification and Cu_2S counter electrode, the PCE reaches a maximum value of 4.26%, which to the best of our knowledge, is among the highest PCE record for CdSe sensitized solar cells based on ZnO photoanodes.
本文首先以水热反应法获得了掺钒的ZnO纳米片薄层,然后通过Na_2S处理和进一步的水热反应在纳米片表面生长出ZnO纳米棒分支结构,以此获得了一种新颖独特的ZnO纳米片-纳米棒三维分等级结构.ZnO纳米棒分支结构的引入,有效地提高了光阳极薄膜的漫反射性能.随后利用电沉积法沉积CdSe量子点研究了其光电化学性能,基于分等级结构光阳极的CdSe量子点敏化太阳电池(QDSSC)的短路电流密度、开路电压以及最终的光电转换效率都比ZnO纳米片光阳极有了显著提升.详细分析了不同的ZnO纳米棒分支生长时间(1,2,4,6和8 h)对器件光电性能的影响.测试结果显示,ZnO纳米棒生长时间为6h所得的分等级样品获得了最高的光电转换效率,在与Cu_2S对电极组装成QDSSC时效率达到了4.26%.
基金
supported by the National Natural Science Foundation of China(51472274)
the Programof Guangzhou Science and Technology(2014J4100016 and 201504010031)
the Pearl River S&T Nova Program of Guangzhou(2014J2200025)
the Natural Science Foundation of Guangdong Province(S2013030013474)
