This paper reports results of a study on the impact that the synthesis method and the replacement of the methylammonium (MA) cation by the formamidinium (FA) cation have on both morphology and degradation of MAPbI₃ (MAPI) films when these are exposed to environmental conditions.

This study was conducted with samples deposited using different routes based on growth methods both in solution and thermal evaporation, including one step spin coating and two-steps new growth routes where in a first step a layer of PbI₂ is deposited by conventional evaporation and then a second layer of MAI (methylammonium iodide) is deposited by dipping and CSS (close spaced sublimation) methods respectively.

The study revealed that the stability of MAPI films is significantly improved when are deposited using the two-steps synthesis routes. Evidence was found explaining that this behavior could be attributed to the fact that this type of MAPI films, grow with large grain sizes and low density of native and structural defects, characteristics that lead to a reduction of the ionic migration initiated in grain boundaries regions, where the degradation process generally begins.

本文报道了以下研究结果：合成方法和甲酰胺（FA）阳离子代替甲基铵（MA）阳离子对暴露于环境中的MAPbI ₃（MAPI）膜的形态和降解都有影响条件。

这项研究是根据溶液和热蒸发中的生长方法，采用不同途径沉积的样品进行的，包括一步旋涂和两步新生长途径，第一步是通过常规蒸发沉积一层PbI ₂，然后通过浸涂和CSS（近距离升华）方法分别沉积第二层MAI（甲基碘化铵）。

研究表明，使用两步合成路线进行沉积时，MAPI膜的稳定性得到了显着改善。证据表明，这种行为可归因于以下事实：这种MAPI膜的生长具有较大的晶粒尺寸，且原生和结构缺陷的密度较低，其特征是导致晶界区域中离子迁移的减少，通常开始降解的地方。