Building Blocks of Hybrid Perovskites: A Photoluminescence Study of Lead-Iodide Solution Species.

ABSTRACT: In this work, we present a detailed investigation of the optical properties of hybrid perovskite building blocks, [PbI_2+n ]^n- , that form in solutions of CH₃ NH₃ PbI₃ and PbI₂ . The absorbance, photoluminescence (PL) and photoluminescence excitation (PLE) spectra of CH₃ NH₃ PbI₃ and PbI₂ solutions were measured in various solvents and a broad concentration range. Both CH₃ NH₃ PbI₃ and PbI₂ solutions exhibit absorption features attributed to [PbI₃ ]^1- and [PbI₄ ]^2- complexes. Therefore, we propose a new mechanism for the formation of polymeric polyiodide plumbates in solutions of pristine PbI₂ . For the first time, we show that the [PbI_2+n ]^n- species in both solutions of CH₃ NH₃ PbI₃ and PbI₂ exhibit a photoluminescence peak at about 760?nm. Our findings prove that the spectroscopic properties of both CH₃ NH₃ PbI₃ and PbI₂ solutions are dominated by coordination complexes between Pb²⁺ and I^- . Finally, the impact of these complexes on the properties of solid-state perovskite semiconductors is discussed in terms of defect formation and defect tolerance.

SUBMITTER: Shargaieva O 

PROVIDER: S-EPMC7702157 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature