Inductive Effect of Lewis Acidic Dopants on the Band Levels of Perovskite for a Photocatalytic Reaction.

Abstract

Band-edge modulation of halide perovskites as photoabsorbers plays significant roles in the application of photovoltaic and photochemical systems. Here, Lewis acidity of dopants (M) as the new descriptor of engineering the band-edge position of the perovskite is investigated in the gradiently doped perovskite along the core-to-surface (CsPbBr3-CsPb1-xMxBr3). Reducing M-bromide bond strength with an increase in hardness of acidic M increases the electron ability of basic Br, thus strengthening the Pb-Br orbital coupling in M-Pb-Br, noted as the inductive effect of dopants. Especially, the highly hard Lewis acidic Mg localized in the outer position of the perovskite induces the increase of work function and then shifts band edge upward along the core-to-surface of the perovskite. Thus, charge separation driven by the dopant-induced internal electric field induces the slow annihilation of the excited holes, improving the slow aromatic Csp3-H dissociation in the photocatalytic oxidation process by ∼211% (491.39 μmol g-1 h-1) enhancements, compared with undoped nanocrystals.