Tracking the formation of methylammonium lead triiodide perovskite
Tracking the formation of methylammonium lead triiodide perovskite
复制标题
追踪甲基铵三碘化铅钙钛矿的形成
DOI：
10.1063/1.4928662
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发表时间：
2015-08-10
影响因子：
4
通讯作者：
Duhm, Steffen
中科院分区：
文献类型：
--
作者：
Liu, Lijia;McLeod, John A.;Duhm, Steffen
利用原位X射线光电子能谱（XPS）研究了碘化铅（PbI2）薄膜上热蒸发甲基碘化铵（CH3NH3I）的连续沉积过程中，钙钛矿相甲基铵三碘化铅（CH3NH3PbI3）的形成机理。这种沉积方法模拟了器件制造中常用的"两步"合成方法。我们发现，几个竞争过程中发生的钙钛矿CH3NH3PbI3的形成。我们最重要的发现是，在气相沉积的CH3NH3I到PbI2上，至少有两个碳物种存在于所得材料中，而只有一个氮物种存在。这表明CH 3 NH3 I在向钙钛矿相转变的过程中可以解离，并且一些所得分子可以掺入钙钛矿中。评估了用CH3部分取代CH3NH3的效果，电子结构计算表明，CH3缺陷会影响钙钛矿太阳能电池的光伏性能。因此，在评估使用典型方法合成的有机金属三卤化物太阳能电池的性能时，并非APbI3钙钛矿中的所有A位点都被CH3NH3占据的可能性是重要的考虑因素。
The formation mechanism of perovskite methylammonium lead triiodide (CH3NH3PbI3) was studied with in situ X-ray photoelectron spectroscopy (XPS) on successive depositions of thermally evaporated methylammonium iodide (CH3NH3I) on a lead iodide (PbI2) film. This deposition method mimics the “two-step” synthesis method commonly used in device fabrication. We find that several competing processes occur during the formation of perovskite CH3NH3PbI3. Our most important finding is that during vapour deposition of CH3NH3I onto PbI2, at least two carbon species are present in the resulting material, while only one nitrogen species is present. This suggests that CH3NH3I can dissociate during the transition to a perovskite phase, and some of the resulting molecules can be incorporated into the perovskite. The effect of partial CH3NH3 substitution with CH3 was evaluated, and electronic structure calculations show that CH3 defects would impact the photovoltaic performance in perovskite solar cells. The possibility that not all A sites in the APbI3 perovskite are occupied by CH3NH3 is therefore an important consideration when evaluating the performance of organometallic trihalide solar cells synthesized using typical approaches.