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Facile Synthesis of Colloidal Lead Halide Perovskite Nanoplatelets via Ligand-Assisted Reprecipitation
Published on: October 1, 2019
13.1K
Pb:Sn Ratio-Driven Polytypism and Band Modulation in Photoresponsive Hexagonal Perovskitoids
Taylor E Wiggins1, Abdulaziz S R Bati1, Mikaël Kepenekian2
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Journal of the American Chemical Society
|June 6, 2025
Summary
Researchers explored mixed-metal hexagonal perovskitoids (APbSnI3) for enhanced stability and tunable optoelectronic properties. They discovered a new polytypic band modulation phenomenon, leading to stable photodiodes.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Optoelectronics
Background:
- Three-dimensional (3D) perovskites (AMX3) offer excellent optoelectronic properties but are limited by cation options and environmental instability.
- Hexagonal perovskitoids present opportunities for enhanced stability and structural diversity but face synthesis and performance challenges.
Purpose of the Study:
- To synthesize and characterize mixed-metal hexagonal perovskitoids (APb1-xSnxI3) with varying tin (Sn) content.
- To investigate the relationship between metal composition, structural evolution, and optoelectronic properties.
- To explore the potential of these materials in optoelectronic devices.
Main Methods:
- Synthesis of a homologous series of hexagonal perovskitoids (APb1-xSnxI3).
- Single-crystal X-ray diffraction (SCXRD) for structural identification (9R, 12R, 6H polytypes).
- Density functional theory (DFT) calculations for electronic structure and site preference.
- Optical spectroscopy and device fabrication (photodiodes).
Main Results:
- Identified three polytypes (9R, 12R, 6H) with increasing corner-sharing connectivity correlating with Sn content.
- Achieved tunable band gaps (1.87–2.51 eV) and observed polytypic band modulation, a combination of band bowing and structural transformation.
- Fabricated photodiodes with stable and pronounced photoresponses.
Conclusions:
- Mixed-metal hexagonal perovskitoids offer a tunable platform for optoelectronic applications.
- The discovered polytypic band modulation provides a new mechanism for tuning material properties.
- Alloying Pb and Sn in hexagonal perovskitoids unlocks a vast, underexplored phase space for materials design.
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