Incorporating a monolayer of WS2 via interface engineering enhances the overall physical properties of a FAPbI3 perovskite based heterostructure. FAPbI3/WS2/TiO2/ITO and FAPbI3/TiO2/ITO heterostructures were analyzed by UV–Vis spectroscopy, x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The configuration with WS2 interlayer presents higher absorption in the visible region with a bandgap of ∼1.45 eV. WS2 also enhances the deposition process of FAPbI3, resulting in the formation of pure photoactive α-phase without the non-photoactive δ-phase or residual plumbates. The incorporation of the monolayer improves the crystalline structure of the FAPbI3, promoting a preferential growth in the [100] direction. The smooth surface of WS2 favors a homogeneous morphology and an increase in the grain size to ∼4.5 μm, the largest reported for similar structures. Furthermore, the work function obtained lets us propose an enhanced an adequate energy band alignment between FAPbI3 and the n-type layers for the electron flux to the cathode. Conductivity and IV curves show a better performance with WS2. These findings strongly suggest that the interfacial coupling of FAPbI3/WS2 could be a promising candidate in photovoltaic applications.

中文翻译：

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WS2 单层集成在基于 FAPbI3 的异质结构中


通过界面工程合并单层 WS2 可增强基于 FAPbI3 钙钛矿异质结构的整体物理性能。通过紫外-可见光谱、X射线衍射、扫描电子显微镜和原子力显微镜对FAPbI3/WS2/TiO2/ITO和FAPbI3/TiO2/ITO异质结构进行了分析。具有 WS2 中间层的结构在可见光区域具有更高的吸收率，带隙为 ∼1.45 eV。 WS2 还增强了 FAPbI3 的沉积过程，从而形成纯光活性 α 相，而没有非光活性 δ 相或残留铅酸盐。单层的引入改善了 FAPbI3 的晶体结构，促进了 [100] 方向的优先生长。 WS2 的光滑表面有利于均匀的形态，并且晶粒尺寸增加至~4.5 μm，这是相似结构中报道的最大尺寸。此外，所获得的功函数让我们建议在 FAPbI3 和 n 型层之间增强适当的能带对准，以实现到达阴极的电子通量。 WS2 的电导率和 IV 曲线显示出更好的性能。这些发现强烈表明 FAPbI3/WS2 的界面耦合可能是光伏应用中很有前途的候选者。