Design and Characterization of Low-Dimensional Perovskites with Multiple-Ring Aromatic Cations

Metal halide perovskites have become promising next-generation semiconducting materials for many applications due to their prominent optoelectronic properties and ease of manufacturing. These materials are widely tailorable in composition, which allows the incorporation of various organic cations. Tuning the structure of the organic molecules can cause remarkable changes in the structural arrangement of halide perovskites resulting in the formation of two-dimensional (2D) layers, one-dimensional (1D) chains, or isolated zero-dimensional (0D) clusters and, as a consequence, the modification of the optoelectronic properties of the perovskite system. <br/>In recent works devoted to the low-dimensional metal halide perovskites, significant attention has been paid to the molecular engineering of the functionalized cations. This allows the design of a variety of new organic-inorganic hybrid materials, in which semiconducting organic and inorganic layers are assembled at the molecular scale. High structural distortion of the resulted low-dimensional perovskite structures induces electron-phonon coupling and enhances the self-trapped excitons (STEs) processes, resulting in an enhanced broadband emission [1,2]. In addition, it has been demonstrated that perovskites grown in a form of atomically thin sheets possess unique features compared to their bulk counterparts [3]. For example, hybrid perovskite sheets exhibit an unusual structural relaxation, which leads to a band gap shift. Consequently, the controllable synthesis of ultrathin perovskite sheets has gained a great research interest for implementation in high-performance optoelectronic devices.<br/>In this work, we fabricated several low-dimensional hybrid organic-inorganic metal halides, based on multiple-ring aromatic ammonium cations and lead iodide with a strong focus on structural and optoelectronic investigation. Examination of the influence of organic cations on the structural properties reveals that the number and position of amino groups at the aromatic ring affect the dimensionality of the perovskite, resulting in 2D and 1D corner- and face-sharing structures with different optical behaviors. Highly distorted 1D perovskites show broadband emissions originating from STEs. Theoretical results reveal, that the organic cations in the 1D compounds strongly contribute to the band structure resulting in strong orbitals hybridization. Using a facile and fast template-assisted crystallization method we have synthesized metal halide perovskite few-layer free-standing nanosheets with micron size containing the naphthalene diammonium-based linker. Varying the synthetic conditions, we can modulate the thickness and lateral sizes of the nanosheets, making them promising candidates for optoelectronic applications.<br/> <br/>[1] A. Mitrofanov et al. <i>J. Mater. Chem. C</i>, <b>2023</b>,11, 5024-5031<br/>[2] Z. Qi et al. <i>Inorg. Chem. </i><b>2021</b>, 60(20), 15136-15140<br/>[3] L. Dou et al. <i>Science</i> <b>2015</b>, 349, 6255