Theoretical and Experimental Insights into Transition Metal Single-Atom Adsorption Effects on Perovskite Surfaces

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High Resolution Image Download MS PowerPoint Slide Perovskite thin films are promising optoelectronic materials because of their low-cost fabrication and high solar cell efficiencies; however, intrinsic defects threaten their stability and scalability by activating degradation pathways. Here, we combine density functional theory calculations with experimental characterization to study the adsorption of transition metals (TMs: Ni, Cu, Ag, Au) on pristine and defect-engineered MAPbI 3 (100) surfaces passivated with methylammonium (MA) cations. Our calculations indicate that subsurface TM substitution is energetically less favorable than surface adsorption, with strong TM–I bonding playing a key role in stabilizing the doped systems. This stability follows the trend Ni > Cu > Au > Ag, highlighting the relative preference of different TMs in interactions with the perovskite structure. Moreover, the presence of iodine vacancies and MA significantly alters both the energetics of adsorption and the electronic structure of the perovskite. Charge analysis demonstrates that Ag, Au, and Cu function as electron donors, resulting in a shift of the Fermi level toward the conduction band, which could enhance the charge transport properties of the material. Reductions in work functions after adsorption suggest that TMs not only enhance surface passivation, but also contribute to lowering electron-extraction barriers, with Cu showing the most pronounced effect in this regard. Complementary field emission scanning electron microscopy and energy-dispersive spectroscopy analyses of TM-coated MAPbI 3 substantiate these findings, revealing distinct metal distributions and demonstrating that Ni achieves the highest surface uniformity, consistent with our computed adsorption energies. These insights advance our understanding of TM-perovskite interactions and support future strategies aimed at enhancing both the stability and performance of perovskite-based photovoltaic devices.