Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles
Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles
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DOI：
10.1021/acsami.5b04695
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发表时间：
2015-09-16
影响因子：
9.5
通讯作者：
Tsang, Sai-Wing
中科院分区：
文献类型：
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作者：
Cheng, Yuanhang;Yang, Qing-Dan;Tsang, Sai-Wing
溶液处理的氧化锌（ZnO）纳米颗粒（NPs）具有优异的电子传输性能和低温工艺，是替代二氧化钛（TiO 2）作为电子传输层以在柔性衬底上开发高效钙钛矿太阳能电池的可行候选物。然而，报道的使用ZnO-NP的高性能钙钛矿太阳能电池的数量仍然有限。在这里，我们报告了详细的调查的化学和晶体生长的CH 3 NH3 PbI 3钙钛矿ZnO-NP薄膜。我们发现，钙钛矿薄膜会严重分解成PbI 2热退火后裸露的ZnO-NP表面上。X射线光电子能谱（XPS）结果表明，ZnO纳米粒子表面的羟基加速了钙钛矿薄膜的分解。为了减少分解，我们在ZnO-NP和钙钛矿层之间引入缓冲层。我们发现，常用的缓冲层与小分子[6，6]-苯基-C61-丁酸甲酯（PC61 BM）可以减缓，但不能完全避免分解。另一方面，使用聚（乙烯亚胺）（PEI）的聚合物缓冲层可以有效地分离ZnO-NP和钙钛矿，这允许通过热退火形成更大的晶体。用PEI代替PC61 BM作为缓冲层，钙钛矿光伏电池的功率转换效率从6.4%显著提高到10.2%。
Solution processed zinc oxide (ZnO) nanopartides (NPs) with excellent electron transport properties and a low-temperature process is a viable candidate to replace titanium dioxide (TiO2) as electron transport layer to develop high-efficiency perovskite solar cells on flexible substrates. However, the number of reported high-performance perovskite solar cells using ZnO-NPs is still limited. Here we report a detailed investigation on the chemistry and crystal growth of CH3NH3PbI3 perovskite on ZnO-NP thin films. We find that the perovskite films would severely decompose into PbI2 upon thermal annealing on the bare ZnO-NP surface. X-ray photoelectron spectroscopy (XPS) results show that the hydroxide groups on the ZnO-NP surface accelerate the decomposition of the perovskite films. To reduce the decomposition, we introduce a buffer layer in between the ZnO-NPs and perovskite layers. We find that a commonly used buffer layer with small molecule [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) can slow down but cannot completely avoid the decomposition. On the other hand, a polymeric buffer layer using poly(ethylenimine) (PEI) can effectively separate the ZnO-NPs and perovskite, which allows larger crystal formation with thermal annealing. The power conversion efficiencies of perovskite photovoltaic cells are significantly increased from 6.4% to 10.2% by replacing PC61BM with PEI as the buffer layer.