The irreversible phase transition by water incorporation, along with thermal decomposition, has long been thought to be the dominant degradation pathway to deteriorate electronic and optoelectronic properties of perovskite devices. However, comprehensive characterization and insightful understanding of beneficial effect of water incorporation remains scarce. Here, we capture the phase transformation of perovskite in situ from its precursor stage to the final film upon thermal annealing as a function of relative humidity (RH) by grazing-incident wide-angle X-ray scattering. Quantitative structural analyses show that a moderate water content (RH 40%) enhances the texture orientation of the perovskite. A consequence of the guided water-incorporated treatment is that the unencapsulated device, without any sophisticated instability-mitigation approaches, exhibits excellent tolerance to long-term, light soaking and high-temperature aging, retaining more than 80% of the peak power-conversion efficiency under constant 1-sun illumination or heating at 65°C for more than 1,000 h, respectively.

长期以来，人们一直认为通过掺入水而发生的不可逆相变以及热分解是使钙钛矿器件的电子和光电性能劣化的主要降解途径。然而，对水掺入的有益效果的全面表征和深入了解仍然匮乏。在这里，我们捕获了原位钙钛矿的相变通过掠入入射的广角X射线散射，将其从前体阶段到最终膜的温度进行热退火，以作为相对湿度（RH）的函数。定量结构分析表明，适度的水含量（相对湿度40％）可增强钙钛矿的质构取向。引导式水结合处理的结果是，未封装的设备无需任何复杂的不稳定性缓解方法，可表现出对长期，轻度浸泡和高温老化的出色耐受性，可保留超过80％的峰值功率转换在恒定的1阳光照射下或在65°C的温度下加热1000小时以上的效率分别较高。