Year: 2026
Type: preprint
Abstract: Organic spacer mixing is a versatile strategy for tuning the structure and properties of two-dimensional layered halide perovskites (2DLHPs), yet the factors that govern the resulting mixing configuration remain poorly understood. Here we investigate mixtures of alkyl monoammonium Ruddlesden–Popper (RP) and alkyl diammonium Dion–Jacobson (DJ) 2DLHPs and identify three structural outcomes: alloying, phase separation, and superlattice formation. Across twenty spacer combinations, the interlayer-spacing mismatch between the parent perovskites largely determines the outcome, with small mismatch favoring alloys and large mismatch favoring phase separation. A superlattice phase with a period exceeding either parent, consistent with alternating RP and DJ layers, forms only at large mismatch and only for blends containing 1,4-butanediammonium (DC4). In situ absorption spectroscopy and single-crystal structure determination reveal that superlattice formation proceeds through a dimethylformamide (DMF)-containing intermediate in which DC4 and n-pentylammonium (C5) occupy distinct bridging and intercalated crystallographic sites, producing an ordered precursor that converts to the superlattice upon annealing. Structural mismatch and intermediate-phase chemistry together govern alloying, phase separation, and superlattice formation in mixed-spacer 2DLHPs.
Source: ChemRxiv
Institution: University of Utah
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214180089