RESEARCH ARTICLE

In-situ organic cation evolution driven sequential crystal transformation in hybrid metal halides

School of Materials Science and Engineering, Tianjin Key Laboratory of Metal and Molecular Materials Chemistry, Frontiers Science Center for New Organic Matter, Academy for Advanced Interdisciplinary Studies, Nankai University, Tianjin 300350, China

^* Corresponding author (email: This email address is being protected from spambots. You need JavaScript enabled to view it. )

Received: 26 January 2026
Revised: 27 February 2026
Accepted: 7 March 2026

Abstract

The properties of organic-inorganic hybrid metal halides (OIHMHs) strongly hinge on their crystal structures. However, structural diversity regulation based on organic-cation design or external stimuli is hindered by the limited diversity of available cations and the random structural changes. Here, we utilize in-situ sequentially generated organic cations from a stepwise reaction between dimethyl sulfoxide (DMSO) and acetone to drive a continuous and unidirectional single-crystal-to-single-crystal transformation in OIHMHs, enabling well-defined and predictable structural evolution. The intermediate dimethyl(2-oxopropyl)sulfonium and product trimethylsulfonium cations are sequentially generated and incorporated into the crystal lattice, giving rise to three types of structurally correlated OIHMHs in both Bi- and Sb-based systems. The resulting OIHMH materials preserve the inorganic photoactive unit while exhibiting systematic changes in their physicochemical properties, revealing a dynamic cooperative mechanism between evolving organic cations and the adaptive inorganic octahedral framework. This work demonstrates the feasibility of intermediate cations generated by organic reactions to serve as an underutilized A-site organic cation resource. Such an organic reaction-driven and inorganic framework-mediated strategy establishes a dynamic paradigm for structural evolution, opening a promising avenue toward precise structural modulations and diversified functionalities of OIHMH materials.