Self limiting atomic layer deposition of Al2O3 on perovskite surfaces: a reality?

The feasibility of self-saturated atomic layer deposition of Al2O3 on an organolead halide perovskite (MAPbI3-xClx) surface through a well known trimethylaluminium (TMA)-water (H2O) chemistry is studied. Though the sequential dosages of reactants form films on the perovskite surfaces, a self saturated growth is never observed. Self-saturation leads to the degradation of the material. Both experimental and density functional theory calculations are carried out for complete understanding of the growth mechanism of self-limiting Al2O3 on the perovskite surface.