Optical and Structural Properties of Perovskite Films Prepared with Two-Step Spin-Coating Method

Perovskite materials have become great research interest due to their superior properties for high power conversion efficiency (PCE) solar cells. Recently, a PCE above 18% is already achieved using perovskite methylamonium lead iodide (CH3NH3PbI3, MAPbI(3)) as active material. High quality crystal of perovskite film as active material is very crucial to be controlled for obtaining high PCE with high environmentally stable solar cells. Spin-coating and dip-coating methods are commonly used to prepare perovskite films for solar cells. However, not all lead(II) iodide PbI2 can be completely converted into perovskite which cause low PCE and deteriorate the stability of solar cells. Therefore, a suitable and simple method for obtaining high quality crystal MAPbI(3) film is highly needed. Herein, we report our current study on the optical, structural and morphological properties of perovskite CH3NH3PbI3 films prepared by use of two-step spin coating method. By using this method, no PbI2 peak is observed in the XRD pattern of perovskite film which proves that all PbI2 was fully converted into perovskite CH3NH3PbI3.