Improved open-circuit voltage in polymer/oxide-nanoarray hybrid solar cells by formation of homogeneous metal oxide core/shell structures.
Improved open-circuit voltage in polymer/oxide-nanoarray hybrid solar cells by formation of homogeneous metal oxide core/shell structures.
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DOI：
10.1021/am400281s
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发表时间：
2013-04
影响因子：
9.5
通讯作者：
Fan Wu;Q. Cui;Zeliang Qiu;Changwen Liu;Hui Zhang;W. Shen;Mingtai Wang
中科院分区：
文献类型：
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作者：
Fan Wu;Q. Cui;Zeliang Qiu;Changwen Liu;Hui Zhang;W. Shen;Mingtai Wang
将金属氧化物（氧化物-NAs）的垂直对齐的纳米棒/纳米线阵列与聚合物结合可以产生具有理想的本体异质结架构的高效混合太阳能电池。然而，聚合物/氧化物-NAs太阳能电池仍然遭受相当低（通常<0.4V）的开路电压（Voc）。在这里，我们展示了，第一次，一种新的策略，以提高Voc的聚合物/氧化物-NAs太阳能电池形成均匀的核/壳结构，并揭示其中所涉及的内在原理。采用水热-溶剂热相结合的方法制备了以单晶纳米棒为核、以相应的金属氧化物量子点聚集层为壳的均匀核壳结构的金属氧化物纳米阵列，壳层厚度（L）可以通过在纳米棒上生长量子点的溶剂热反应时间来控制。核/壳形成显著地将器件Voc提高至约100。0.7-0.8 V，取决于L。基于稳态和动态测量，以及空间电荷限制电流方法的模拟，发现Voc的提高源于壳层生长后光生电子和空穴之间的迁移率差减小而引起的界面偶极场使芯中的导带边缘上移，对于较高的Voc，这增加了核中光生电子的准费米能级与聚合物中空穴的准费米能级之间的能量差。我们的研究结果表明，增加Voc的核/壳策略似乎不依赖于金属氧化物的种类。
Incorporation of vertically aligned nanorod/nanowire arrays of metal oxide (oxide-NAs) with a polymer can produce efficient hybrid solar cells with an ideal bulk-heterojunction architecture. However, polymer/oxide-NAs solar cells still suffer from a rather low (normally, < 0.4 V) open-circuit voltage (Voc). Here we demonstrate, for the first time, a novel strategy to improve the Voc in polymer/oxide-NAs solar cells by formation of homogeneous core/shell structures and reveal the intrinsic principles involved therein. A feasible hydrothermal-solvothermal combined method is developed for preparing homogeneous core/shell nanoarrays of metal oxides with a single-crystalline nanorod as core and the aggregation layer of corresponding metal oxide quantum dots (QDs) as shell, and the shell thickness (L) is easily controlled by the solvothermal reaction time for growing QDs on the nanorod. The core/shell formation dramatically improves the device Voc up to ca. 0.7-0.8 V depending on L. Based on steady-state and dynamic measurements, as well as modeling by space-charge-limited current method, it is found that the improved Voc originates from the up-shifted conduction band edge in the core by the interfacial dipole field resulting from the decreased mobility difference between photogenerated electrons and holes after the shell growth, which increases the energy difference between the quasi-Fermi levels of photogenerated electrons in the core and holes in the polymer for a higher Voc. Our results indicate that increasing Voc by the core/shell strategy seems not to be dependent on the kinds of metal oxides.