AVS 65th International Symposium & Exhibition
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA9
Strong Effect of Reaction Temperature on the Nucleation of Atomic Layer Deposition of Al2O3 on Methylamine Lead Perovskite

Monday, October 22, 2018, 4:00 pm, Room 104B

Session: IoT Session: Thin Films for Photovoltaics
Presenter: Xiaozhou Yu, University of Alabama
Authors: X. Yu, University of Alabama
H.M. Yan, University of Alabama
Q. Peng, University of Alabama
Correspondent: Click to Email
Hybrid perovskite solar cells have attracted tremendous attention due to the low cost and high-power conversion efficiency. The biggest barrier to its commercialization is the poor stability in the outdoor environment.Al2O3 atomic layer deposition (ALD) has shown great promise in improving the environmental stability of hybrid perovskites, however, the nucleation of ALD Al2O3 on perovskite has not yet been understood, especially the reaction between tri-methyl aluminum (TMA), a strong Lewis acid, and fresh hybrid perovskites. In our work, the growing behavior and surface reaction mechanism of Al2O3 ALD (Trimethyl Aluminum (TMA) and H2O chemistry) on CH3NH3PbI3 perovskite is studied systematically by in situquartz crystal microbalance(QCM) and in situquadrupole mass spectrometers (QMS).We find that the reaction temperature is the key parameter affecting the nucleation of Al2O3 ALD on CH3NH3PbI3. At 25°C, TMA can accumulate mass onto the surface of a fresh CH3NH3PbI3 substrate through substrate site-limited reactions. The surface passivation provided by TMA adsorption at 25°C improves the ambient stability of CH3NH3PbI3. In contrast, at 75°C, TMA etches CH3NH3PbI3 by the formation of volatile products, which will degrade CH3NH3PbI3 to PbI2.