The formamidinium lead iodide (FAPbI₃) perovskite has attracted immense research interest as it has much improved stability than methylammonium lead iodide (MAPbI₃) while still maintaining excellent optoelectronic properties. Compared to MAPbI₃, FAPbI₃ has shown an elevated decomposition temperature and a slower decomposition process and therefore it is considered as a more promising candidate for future high-efficiency and reliable optoelectronic devices. However, these excellent optoelectronic properties only exist in the alpha phase and this phase will spontaneously transform into an undesired delta phase with much poorer optoelectronic properties regardless of the environment. This is the main challenge for the application of the FAPbI₃ perovskite. Herein, we report a novel strategy to stabilize the cubic black phase of FAPbI₃ by using nanoengineering templates. Without further treatment, the black phase can be held over 7 months under ambient conditions and 8 days in an extreme environment with a Relative Humidity (RH) of 97%. A systematic study further reveals that this great improvement can be attributed to the spatial confinement in anodized alumina membrane (AAM) nanochannels, which prohibits the unwanted α-to-δ phase transition by restricting the expansion of NWs in the ab plane, and the excellent passivation against water molecule invasion. Meanwhile, we also demonstrate the potency of these NWs in practical applications by configuring them into photodetectors, which have shown reasonable response and excellent device stability.

中文翻译：

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通过在纳米多孔模板中进行空间受限的气相生长， 显着提高了FAPbI ₃纳米线的黑相稳定性†

甲酰碘化碘化铅（FAPbI ₃）钙钛矿吸引了巨大的研究兴趣，因为它比甲基铵碘化铅（MAPbI ₃）具有更高的稳定性，同时仍保持了优异的光电性能。与MAPbI ₃相比，FAPbI ₃已经显示出升高的分解温度和较慢的分解过程，因此，它被认为是未来高效和可靠的光电器件的更有希望的候选者。然而，这些优异的光电性能仅存在于α相中，并且无论环境如何，该相都会自发地转变为具有差得多的光电性能的不期望的δ相。这是应用FAPbI ₃钙钛矿的主要挑战。在此，我们报告了一种稳定FAPbI ₃立方黑相的新策略通过使用纳米工程模板。无需进一步处理，黑相可以在环境条件下保持7个月以上，在相对湿度（RH）为97％的极端环境中保持8天。一项系统的研究进一步表明，这一重大改进可归因于阳极氧化铝膜（AAM）纳米通道中的空间限制，它通过限制ab平面中NW的膨胀来阻止不希望的α到δ相转变，并且出色的钝化水分子入侵。同时，我们还通过将它们配置为光电探测器来证明这些NW在实际应用中的潜力，这些探测器显示出合理的响应和出色的器件稳定性。