Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
Nanoscale. 2019 Mar 28;11(13):5989-5997. doi: 10.1039/c8nr10267h.
Formamidinium lead iodide (FAPbI3) is one of the most extensively studied perovskite materials due to its narrow band gap and high absorption coefficient, which makes it highly suitable for optoelectronic applications. Deposition of a solution containing lead iodide (PbI2) and formamidinium iodide (FAI) or sequential deposition of PbI2 and FAI usually leads to the formation of films with a poor morphology and an unstable crystal structure that readily crystallize into two different polymorphs: the photoinactive yellow phase and the photoactive black phase. In this work, 2D 2-phenylethylammonium lead iodide (PEA2PbI4) thin films are deposited by a scalable doctor-blade coating technique and used as a growth template for the high-quality 3D FAPbI3 perovskite thin films which are obtained by organic cation exchange. We report the structural, morphological and optical properties of these converted 3D FAPbI3 perovskite films which we compare to the directly deposited 3D FAPbI3 films. The converted FAPbI3 thin films are compact, smooth, and highly oriented and exhibit better structural stability in comparison with the directly deposited 3D films. These results not only underscore the importance of the employed deposition techniques in fabricating highly crystalline and stable perovskite thin films but also provide a strategy to easily obtain very compact perovskite layers using doctor-blade coating.
碘化甲脒铅（FAPbI3）是研究最广泛的钙钛矿材料之一，因为其具有窄带隙和高吸收系数，使其非常适合光电应用。沉积含有碘化铅（PbI2）和甲脒碘（FAI）的溶液或顺序沉积 PbI2 和 FAI 通常会导致形成形貌较差且晶体结构不稳定的薄膜，容易结晶成两种不同的多晶型物：非活性的黄色相和活性的黑色相。在这项工作中，通过可扩展的刮刀涂布技术沉积二维 2-苯乙基碘化铵（PEA2PbI4）薄膜，并用作高质量 3D FAPbI3 钙钛矿薄膜的生长模板，该薄膜通过有机阳离子交换获得。我们报告了这些转化的 3D FAPbI3 钙钛矿薄膜的结构、形貌和光学性质，并将其与直接沉积的 3D FAPbI3 薄膜进行了比较。与直接沉积的 3D 薄膜相比，转化的 FAPbI3 薄膜更致密、更光滑、更取向，并且具有更好的结构稳定性。这些结果不仅强调了所采用的沉积技术在制备高结晶度和稳定的钙钛矿薄膜方面的重要性，而且还提供了一种使用刮刀涂布轻松获得非常致密钙钛矿层的策略。
