Picoperovskites: The Smallest Conceivable Isolated Halide Perovskite Structures Formed within Carbon Nanotubes

Halide perovskite structures are revolutionizing the design of optoelectronic materials, including solar cells, light-emitting diodes, and photovoltaics when formed at the quantum scale. Four isolated sub-nanometer, or picoscale, halide perovskite structures formed inside approximate to 1.2-1.6 nm single-walled carbon nanotubes (SWCNTs) by melt insertion from CsPbBr3 and lead-free CsSnI3 are reported. Three directly relate to the ABX(3) perovskite archetype while a fourth is a perovskite-like lamellar structure with alternating Cs-4 and polyhedral Sn4Ix layers. In approximate to 1.4 nm-diameter SWCNTs, CsPbBr3 forms (Cs3PbBr5)-Br-II nanowires, one ABX(3) unit cell in cross section with the Pb2+ oxidation state maintained by ordered Cs+ vacancies. Within approximate to 1.2 nm-diameter SWCNTs, CsPbBr3 and CsSnI3 form inorganic-polymer-like bilayer structures, one-fourth of an ABX(3) unit cell in cross section with systematically reproduced ABX(3) stoichiometry. Producing these smallest halide perovskite structures at their absolute synthetic cross-sectional limit enables quantum confinement effects with first-principles calculations demonstrating bandgap widening compared to corresponding bulk structural forms.

Automated summary

Halide perovskite structures formed at the quantum scale are revolutionizing optoelectronic materials design, such as solar cells and light-emitting diodes. Four sub-nanometer halide perovskite structures were successfully created inside single-walled carbon nanotubes, demonstrating unique properties and bandgap widening compared to bulk forms. These structures show promise in the development of advanced optoelectronic devices.