Paper TF-MoA1
Probe the Reaction Chemistry during Atomic Layer Deposition onto CH₃NH₃PbI₃

Monday, October 30, 2017, 1:40 pm, Room 20

The rapid development of organic-inorganic hybrid halide perovskites, represented by CH₃NH₃PbI₃, based solar cells is one of the major scientific breakthroughs of recent years. It is superior optoelectronic properties inspired applications beyond solar cells, including LEDs, transistors, and sensors. Thin metal oxide coatings are promising electron extraction layer, moisture barrier, electron injection layer, electron blocking layer, and high-k dielectrics for semiconducting CH₃NH₃PbI₃. Atomic layer deposition (ALD) is a promising method to directly put these metal oxides onto CH₃NH₃PbI₃. The pure heterogeneous reaction mechanisms provide ALD the capability to deliver conformal films on substrates of complex morphology with sub-nanometer control of the composition and thickness of the film. On the other hand, the heterogeneous-reaction-driven film growth mode in ALD process demands a molecular level understanding of the heterogeneous reaction chemistry. In this presentation, we will show the surface reaction mechanisms of ALD oxide on CH₃NH₃PbI₃ by using a suite of in-situ and ex-situ analytic methods. Our results show that the heterogeneous reaction chemistries of ALD during the nucleation stage of ALD oxide on CH₃NH₃PbX₃ is complex. Based on these fundamental understandings, we will further show that one can control the formation of the oxide layer by ALD through the careful control of the ALD chemistry and process conditions.