Overcoming Electrode‐Induced Losses in Organic Solar Cells by Tailoring a Quasi‐Ohmic Contact to Fullerenes via Solution‐Processed Alkali Hydroxide Layers
Overcoming Electrode‐Induced Losses in Organic Solar Cells by Tailoring a Quasi‐Ohmic Contact to Fullerenes via Solution‐Processed Alkali Hydroxide Layers
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DOI：
10.1002/aenm.201502195
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发表时间：
2016-05
影响因子：
27.8
通讯作者：
Hong Zhang;R. C. Shallcross;Ning Li;T. Stubhan;Yi Hou;Wei Chen;T. Ameri;M. Turbiez;N. Armstrong-N
中科院分区：
文献类型：
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作者：
Hong Zhang;R. C. Shallcross;Ning Li;T. Stubhan;Yi Hou;Wei Chen;T. Ameri;M. Turbiez;N. Armstrong-N
结果表明，在n型金属氧化物（铝氧化锌，AZO和氧化锌，ZnO）层上，通过溶液处理的氢氧化碱（AOH）中间层促进准欧姆接触的形成，可以显著提高倒置有机太阳能电池的性能。AOHs显著降低了金属氧化物的功函数，并被进一步证明能有效钝化这些金属氧化物中的缺陷态。研究了这些电子收集接触与原型电子受体（C60）的界面能量学，揭示了AOH修饰的AZO接触在费米能和C60最高占据分子轨道之间存在一个大的界面偶极子和一个新的界面态。这些新的界面间隙状态是基态电子从金属氢氧化物功能化的AZO接触转移到被吸附分子的结果，这些分子被假设与接触发生了电子杂化。这些界面状态一直延伸到费米能量，提供了一个高氮掺杂（类似金属）的界面分子层。此外，在具有AOH界面的器件中不再观察到强烈的“光浸泡”效应。
It is shown that the performance of inverted organic solar cells can be significantly improved by facilitating the formation of a quasi‐ohmic contact via solution‐processed alkali hydroxide (AOH) interlayers on top of n‐type metal oxide (aluminum zinc oxide, AZO, and zinc oxide, ZnO) layers. AOHs significantly reduce the work function of metal oxides, and are further proven to effectively passivate defect states in these metal oxides. The interfacial energetics of these electron collecting contacts with a prototypical electron acceptor (C60) are investigated to reveal the presence of a large interface dipole and a new interface state between the Fermi energy and the C60 highest occupied molecular orbital for AOH‐modified AZO contacts. These novel interfacial gap states are a result of ground‐state electron transfer from the metal hydroxide‐functionalized AZO contact to the adsorbed molecules, which are hypothesized to be electronically hybridized with the contact. These interface states tail all the way to the Fermi energy, providing for a highly n‐doped (metal‐like) interfacial molecular layer. Furthermore, the strong “light‐soaking” effect is no longer observed in devices with a AOH interface.