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Title: Three-Dimensional Hybrid Perovskitoid Single Crystals Constructed with Di- and Monoammonium Cations for Light- Emission and Photodetection

Authors: M. Mączka*, D. Drozdowski, D. Stefańska, B. Popanda, V. Anilkumar, D. Prochowicz

Journal: Chemistry of Materials

DOI: 10.1021/acs.chemmater.6c01171

Hybrid lead halide perovskitoids with extended 3D connection modes have attracted a lot of attention for optoelectronic and photodetection applications, but up to now,

only one example comprising divalent and monovalent cations is known, i.e., MPDA₂FAPb₄Br₁₃ (MPDA = N-methylpropanediammonium, FA = formamidinium). In this article, Prof. Mączka with co-workers and collaborators from the Institute of Physical Chemistry PAS, reports the synthesis of three new analogues with formula MPDA₂APb₄Br₁₃ (A= methylammonium (MA), ethylammonium (EA), or dimethylammonium (DMA)). Structural and optical investigations revealed that all compounds crystallize in the monoclinic P2/m space group and exhibit both narrowband and broadband photoluminescence accompanied by pronounced thermochromism. The authors demonstrated that the intensity of the broadband emission increases with increasing octahedral distortion, establishing a structure-property relationship. Furthermore, a single-crystal photodetector fabricated from MPDA₂MAPb₄Br₁₃ operates at a remarkably low bias voltage of only 0.5 V while maintaining stable photocurrent over repeated illumination cycles, demonstrating excellent device reliability.

In summary, Prof. Mączka’s work expands the very small family of mixed-cation 3D hybrid perovskitoids by three new members and shows for the first time that the relaxed Goldschmidt tolerance rule is valid not only for 2D perovskites but also for 3D perovskitoids. It also demonstrates tunable optical properties, and strong potential for light-emitting and low-power photodetection applications.

Highlights:

• Synthesis of three new mixed-cation hybrid lead bromide 3D perovskitoids incorporating MA, EA, and DMA cations, adopting monoclinic P2/m symmetry, isostructural to known formamidinium based analog.
• Establishment of a structure-property correlation between broadband photoluminescence intensity and the degree of intraoctahedral distortion, particularly of corner-sharing PbBr₆ octahedra.
• Fabrication of a single-crystal MPDA₂MAPb₄Br₁₃ photodetector operating at a low bias voltage of 0.5 V while maintaining stable photocurrent during repeated operation.