Lead iodide and cesium lead halide perovskite highly oriented films deposited by spin coating

Spin-coated films are usually polycrystalline or amorphous, while some special materials such as lead iodide (PbI2) and inorganic perovskite could be deposited onto a variety of single-crystal substrates by spin coating obtaining highly oriented films. Herein, we report an effective method for depositing highly textured PbI2 and CsPbI2Br films—via spin coating. An unexpected high-quality PbI2 film with uniform out-plane orientation of the {001} plane was deposited on the gallium nitride substrate, which was benefited from heterogeneous nucleation measured by high-resolution x-ray diffraction (XRD) and Raman mapping. Furthermore, the α-phase CsPbI2Br highly oriented film was deposited on single-crystal (100) silicon with only the (200) plane for the first time. Compressive stress was found both in PbI2 film and in CsPbI2Br film via XRD, Raman spectra, and photoluminescence spectroscopy. Density functional theory calculations were performed to confirm that CsPbI2Br had a tetragonal structure rather than an orthogonal structure.