Title: Phase Transitions, Dielectric Response, and Nonlinear Optical Properties of Aziridinium Lead Halide Perovskites
Authors: M. Mączka, M. Ptak, A. Gągor, J.K. Zaręba, X. Liang, S. Balčiu̅nas, O.A. Semenikhin, O.I. Kucheriv, I.A. Gural’skiy, S. Shova, A. Walsh, J. Banys, M. Šimėnas
Journal: Chemistry of Materials
DOI: 10.1021/acs.chemmater.3c02200

The most current outcomes of Prof. Mączka’s collaboration are presented in this publication. A whole international team is working on hybrid organic-inorganic 3D perovskites, which are potential candidates for solar cells, light-emitting diodes, photodetectors, and laser applications. The research focuses on the development and characterization of novel 3D perovskites based on aziridinium cation (AZR+) – AZRPbX3 (X=Cl, Br, I). This is just the fourth known cation capable of generating three-dimensional structures with the lead-halide framework.
The quality performance of perovskite-like material is controlled by its structural and dynamic properties, phase transition character, and stability. As a result, a multitechnique experimental and theoretical approach was used in this work to determine the primary features associated with the phase transitions in the AZRPbX3 family. According to the structural investigations, all three analogues undergo an order-disorder phase transition, and the high-temperature cubic perovskite structure is retained down to 132-162 K, depending on the halide ion. Below that temperature, AZR+ cations freeze abruptly, as validated by dielectric and phonon studies as well as molecular dynamics simulations. Corresponding dielectric permittivity values are expected to provide efficient screening of the photogenerated carriers and defect sites in devices employing these materials. Despite the fact that all studied halides are centrosymmetric, a strong two- or three-photon excited luminescence was observed. The optical data also indicated that AZRPbBr3 and AZRPbI3 have substantial nonlinear optical absorption, making these perovskites promising candidates for NLO applications.

Highlights:
- A new class of 3D halide perovskites has been discovered
- Phase transition mechanisms have been characterized
- The molecular dynamics of aziridinium cations has been described
- The utility of optoelectronic applications has been evaluated