(Invited) Vacuum Deposition and Crystal Growth of Organolead Halide Perovskite

Abstract

Perovskite solar cells are developing very rapidly and have attracted much attention because of their high power-conversion efficiencies (PCE). Fabrication control of perovskite crystal is important because the reproducibility of the device performance is important issue for perovskite solar cells. We have been focusing on vacuum deposition for the precise control of the fabrication of perovskite. We demonstrated that laser deposition method is useful for the precise deposition-rate control of methylamine iodide[1], where its high vapor pressure makes it difficult to control its deposition rate by conventional deposition method. By taking the advantage of deposition control, we focused on the crystal growth and crystal-growth analysis of perovskite. In this paper, the technical aspects of laser deposition method will be addressed, followed by fabrication of perovskite solar cells [1], epitaxial growth [2] and growth dynamics analysis using laser deposition method.Firstly, we implemented laser deposition for the deposition of perovskite, where the source materials (PbI2, CH3NH3I) were heated with the IR continuous-wave laser. The PID control system was implemented to adjust the deposition rate and the stabilized evaporation rate was achieved. Perovskite solar cells were constructed using the cell structure of ITO/PEDOT:PSS/NiOx/PCDTBT/CH3NH3PbI3/PCBM/BCP/Al and power conversion efficiency of 16% was obtained.Next, we attempted epitaxial growth of CH3NH3PbI3 on (1 0 0) oriented rubrene single crystals to obtain highly ordered perovskite crystal. We succeeded in the epitaxial growth of perovskite both by a co-deposition method and an alternative deposition method. The precise crystal orientation and crystallization dynamics were analyzed using grazing incident wide angle X-ray scattering (GIWAXS) at a synchrotron radiation facility (SPring-8, BL46XU).