Unveiling the Interaction Between Fragments of ABX3 Halide Perovskite and Ti3C2F2 MXene Monolayer

Abstract

The promising potential of halide perovskites and two-dimensional (2D) MXenes enables the rational design of interfaces for optimized, next-generation, photovoltaic perovskite-based technologies. Building upon this premise, we investigate the interaction between fragments of halide perovskite and 2D MXene materials through ab initio simulations. The investigated fragments of ABX₃ perovskites cover ions (A⁺, B²⁺, and X⁻) beyond the neutral small molecules (AX and BX₂), whereas A⁺ = MA⁺, FA⁺, Cs⁺; B²⁺ = Pb²⁺; and X⁻ = Cl⁻, Br⁻, and I⁻. These fragments were adsorbed onto the Ti₃C₂F₂ MXene surface, considering diverse adsorption sites and initial molecular orientations, resulting in a configuration set of 216 arrangements. We identify the most stable adsorption configurations, showing that A⁺ cations bind strongly to the MXene with adsorption energies lower than −2.00 eV, typical of chemisorption. Halide anions X⁻ display intermediate interactions varying from −0.60 eV to −1.80 eV that scale with electronegativity, and both the cation B²⁺ and neutral fragments AX and BX₂ exhibit energies ranging from −0.50 eV to approximately −0.80 eV, demonstrating a relatively strong adsorption for all fragments. Moreover, significant distortions at the MXene bond lengths near the adsorption site were observed, with elongations exceeding 13% in some cases. The adsorption also alters molecular geometries, yielding mean relative errors surpassing 3.5% even for some neutral fragments, as in the cases of MACl and CsX. Quantitative discrepancies between adsorption and interaction energies reflect these deformations. Finally, we characterize the electronic properties, revealing that FA⁺, Pb²⁺, and I⁻ introduce states at the Fermi level, while other fragments such as MAX, FAX, and CsX add states near the Fermi level whose proximity systematically increases with the X⁻ halide species, following the order Cl⁻ < Br⁻ < I⁻. Thus, our simulation maps the interaction property according to the composition and highlights I⁻ and I⁻-based halide fragments as the most relevant species for modulating the electronic properties of MXene, and in this way, we unveil the interfacial interaction mechanisms, providing key insights for supporting future experimental efforts directed toward next-generation photovoltaic applications.