Molecular behavior of zero-dimensional perovskites

• Published in: Science advances Vol. 3; no. 12; p. e1701793
• Main Authors: Yin, Jun, Maity, Partha, De Bastiani, Michele, Dursun, Ibrahim, Bakr, Osman M., Brédas, Jean-Luc, Mohammed, Omar F.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01.12.2017
• Subjects: Physical Sciences; Physics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.1701793

Researchers provide new insights into the formation of small polarons in zero-dimensional perovskites. Low-dimensional perovskites offer a rare opportunity to investigate lattice dynamics and charge carrier behavior in bulk quantum-confined solids, in addition to them being the leading materials in optoelectronic applications. In particular, zero-dimensional (0D) inorganic perovskites of the Cs 4 PbX 6 (X = Cl, Br, or I) kind have crystal structures with isolated lead halide octahedra [PbX 6 ] 4− surrounded by Cs + cations, allowing the 0D crystals to exhibit the intrinsic properties of an individual octahedron. Using both experimental and theoretical approaches, we studied the electronic and optical properties of the prototypical 0D perovskite Cs 4 PbBr 6 . Our results underline that this 0D perovskite behaves akin to a molecule, demonstrating low electrical conductivity and mobility as well as large polaron binding energy. Density functional theory calculations and transient absorption measurements of Cs 4 PbBr 6 perovskite films reveal the polaron band absorption and strong polaron localization features of the material. A short polaron lifetime of ~2 ps is observed in femtosecond transient absorption experiments, which can be attributed to the fast lattice relaxation of the octahedra and the weak interactions among them.