The Role of Connectivity on Electronic Properties of Lead Iodide Perovskite-Derived Compounds.

ABSTRACT: We use a layered solution crystal growth method to synthesize high-quality single crystals of two different benzylammonium lead iodide perovskite-like organic/inorganic hybrids. The well-known (C₆H₅CH₂NH₃)₂PbI₄ phase is obtained in the form of bright orange platelets, with a structure comprised of single ?100?-terminated sheets of corner-sharing PbI₆ octahedra separated by bilayers of the organic cations. The presence of water during synthesis leads to formation of a novel minority phase that crystallizes in the form of nearly transparent, light yellow bar-shaped crystals. This phase adopts the monoclinic space group P2₁/n and incorporates water molecules, with structural formula (C₆H₅CH₂NH₃)₄Pb₅I₁₄·2H₂O. The crystal structure consists of ribbons of edge-sharing PbI₆ octahedra separated by the organic cations. Density functional theory calculations including spin-orbit coupling show that these edge-sharing PbI₆ octahedra cause the band gap to increase with respect to corner-sharing PbI₆ octahedra in (C₆H₅CH₂NH₃)₂PbI₄. To gain systematic insight, we model the effect of the connectivity of PbI₆ octahedra on the band gap in idealized lead iodide perovskite-derived compounds. We find that increasing the connectivity from corner-, via edge-, to face-sharing causes a significant increase in the band gap. This provides a new mechanism to tailor the optical properties in organic/inorganic hybrid compounds.

SUBMITTER: Kamminga ME 

PROVIDER: S-EPMC5516709 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature