Organic cation directed hybrid lead halides of zero-dimensional to two-dimensional structures with tunable photoluminescence properties

Abstract

Recently, organic–inorganic hybrid lead halides have been explored as photoluminescent (PL) materials with flexible structural tunabilities and high photoluminescence quantum efficiencies, which can be modified by the structure regulating functions of organic cations. Here, by adopting different saturated organic cations as structure directing agents (SDAs), a series of organic–inorganic hybrid lead halides have been solvothermally synthesized and characterized with different structural types. Compound [(CH₃)₂NH₂]₂[H₂DABCO]₂Pb₃I₁₂ (1, DABCO = 1,4-diazabicyclo[2.2.2]-octane) features a linear zero-dimensional (0D) [Pb₃I₁₂]⁶⁻ trimer, and [(Me)₆-en]₂Pb₃I₁₀ (2) and [H₂N-Prpipz]₂Pb₃Br₁₀ (3) contain two different types of one-dimensional (1D) [Pb₃X₁₀]⁴⁻ chains based on the C₃-symterric [Pb₃X₁₁] trimer and [PbX₆] unit, respectively. In the structures of H[(Me)₂-DABCO]Pb₃I₉ (4) and H[(Me)₄-pipz]Pb₃I₉ (5, pipz = piperazine), the C₃-symmetric [Pb₃I₁₁] trimers are interlinked to form the same two-dimensional (2D) corrugated [Pb₃I₉]³⁻ layers. Under the excitation of UV irradiation, these hybrid lead halides exhibit tunable luminescence properties from yellow, orange to red emissions with the largest Stokes shift of 335 nm. The PL nature is also investigated based on temperature-dependent PL emission, time-resolved PL and theoretical calculations, etc. These hybrid lead halides provide new types of structural models to probe into the PL properties and understand the underlying structure–property relationship.