Controllable deposition of organic metal halide perovskite films with wafer-scale uniformity by single source flash evaporation

Conventional solution-processing techniques such as the spin-coating method have been used successfully to reveal excellent properties of organic-inorganic halide perovskites (OHPs) for optoelectronic devices such as solar cell and light-emitting diode, but it is essential to explore other deposition techniques compatible with large-scale production. Single-source flash evaporation technique, in which a single source of materials of interest is rapidly heated to be deposited in a few seconds, is one of the candidate techniques for large-scale thin film deposition of OHPs. In this work, we investigated the reliability and controllability of the single-source flash evaporation technique for methylammonium lead iodide (MAPbI₃) perovskite. In-depth statistical analysis was employed to demonstrate that the MAPbI₃ films prepared via the flash evaporation have an ultrasmooth surface and uniform thickness throughout the 4-inch wafer scale. We also show that the thickness and grain size of the MAPbI₃ film can be controlled by adjusting the amount of the source and number of deposition steps. Finally, the excellent large-area uniformity of the physical properties of the deposited thin films can be transferred to the uniformity in the device performance of MAPbI₃ photodetectors prepared by flash evaporation which exhibited the responsivity of 0.2 A/W and detectivity of 3.82 × 10¹¹ Jones.