Improving the stability and decreasing the trap state density of mixed-cation perovskite solar cells through compositional engineering†,Sustainable Energy & Fuels

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Improving the stability and decreasing the trap state density of mixed-cation perovskite solar cells through compositional engineering†
Sustainable Energy & Fuels ( IF 5.0 ) Pub Date : 2018-04-17 00:00:00 , DOI: 10.1039/c8se00127h
Kianoosh Poorkazem _{1,

2,

3,

4} , Timothy L. Kelly _{1,

2,

3,

4}

Affiliation

In order to become a commercially viable technology, perovskite solar cells will require both high efficiencies and long-term stability. Many of the highest efficiency devices reported to date have used complex perovskite formulations synthesized from PbI₂, formamidinium iodide, PbBr₂, and CH₃NH₃Br; the addition of a small amount of CsI to this composition can further improve the device efficiency. Unfortunately, previous work has also shown that the methylammonium cation can not only make the perovskite more hygroscopic, it also renders it susceptible to photochemical decomposition; additionally, mixed-halide perovskite compositions have been shown to suffer from a phenomenon known as halide segregation. Here we show that both PbBr₂ and CH₃NH₃Br can be omitted from Cs-containing perovskite devices with little change in device efficiency. We also show that replacing these components with PbI₂ and guanidinium iodide leads to a decrease in the trap state density and an increase in the open-circuit voltage. Importantly, the mixed-cation perovskite shows improved moisture resistance and photochemical stability in both thin films and devices.

中文翻译：

通过组成工程提高混合阳离子钙钛矿太阳能电池的稳定性并降低其陷阱态密度†

为了成为商业上可行的技术，钙钛矿太阳能电池将需要高效率和长期稳定性。许多迄今报道的最高的效率装置的已使用从合成碘化铅复合钙钛矿配制剂₂，甲脒，碘化PbBr ₂，和CH ₃ NH ₃溴; 向该组合物中添加少量的CsI可以进一步提高器件效率。不幸的是，先前的研究还表明，甲基铵阳离子不仅可以使钙钛矿具有更大的吸湿性，而且还使其易于光化学分解。另外，已经显示出混合卤化物钙钛矿组合物遭受称为卤化物偏析的现象。在这里，我们显示两种PbBr含Cs的钙钛矿型器件可以省略CH₂和CH₃ NH₃ Br，而器件效率几乎没有变化。我们还表明，用PbI₂和碘化胍代替这些组分会导致陷阱态密度的降低和开路电压的增加。重要的是，混合阳离子钙钛矿在薄膜和器件中均显示出改进的耐湿性和光化学稳定性。

更新日期：2018-04-17

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