Effect of the rigidity of an organic interlayer on the nonradiative recombination and exciton dissociation in hybrid Dion–Jacobson 2D lead iodide perovskites

Abstract

Two-dimensional (2D) hybrid halide perovskites offer tremendous potential in optoelectronics, yet their efficiency has not rivaled that of their three-dimensional (3D) counterparts. This study explores the tuning of 2D perovskite rigidity by varying organic ions and their hydrogen bonding modes to influence nonradiative recombination. Specifically, within the Dion–Jacobson 2D perovskites, the (3AMP)(FA)Pb₂I₇ structure exhibits superior hydrogen bonding symmetry between the 3AMP⁺ organic cation and inorganic octahedron, producing a well-organized, robust perovskite lattice. This contrasts with the asymmetric hydrogen connection mode observed in the 4AMP⁺ based system, which leads to a significant lattice distortion with a soft 2D structure. The higher rigidity and structural regularity of the 3AMP⁺ based 2D perovskite contribute to reducing the defect formation probabilities during perovskite crystallization, as well as mitigating the electron–phonon coupling strength via restraining lattice vibrations. In addition, the 3AMP-based system exhibits an ideal distribution of charges between the conduction band minimum (CBM) and valence band maximum (VBM), which facilitates efficient exciton dissociation. These synergies diminish the nonradiative recombination in 3AMP-based 2D perovskite films, outperforming the 4AMP-based systems in photovoltaic efficiency. Our findings pave the way for a more informed design and selection of 2D organic cations, steering the development of high-performance 2D PSCs.