Double perovskites (DP) have attracted extensive attention due to their rich structures and wide application prospects in the field of optoelectronics. Here, we report 15 new Bi‐based double perovskite derived halides with the general formula of A2BBiX6 (A=organic cationic ligand, B=K or Rb, X=Br or I). These materials are synthesized using organic ligands to coordinate with metal ions with a sp3 oxygen, and diverse structure types have been obtained with distinct dimensionalities and connectivity modes. The optical band gaps of these phases can be tuned by changing the halide, the organic ligand and the alkali metal, varying from 2.0 to 2.9 eV. The bromide phases exhibit increasing photoluminescence (PL) intensity with decreasing temperature, while the PL intensity of iodide phases changes nonmonotonically with temperature. Because the majority of these phases are non‐centrosymmetric, second harmonic generation (SHG) responses are also measured for selected non‐centrosymmetric materials, showing different particle‐size‐dependent trends. Our findings give rise to a series of new structural types to the DP family, and provide a powerful synthetic handle for symmetry breaking.
The luminescence dissymmetry factor (g lum ) is used to quantify the level of CPL and defined as 2 × (I left − I right )/(I left + I right ), where I left and I right are the intensity of the left-and right-handed circularly polarized light, respectively. [13] The theoretical minimum and maximum value of |g lum | is 0 and 2, corresponding to non polarized and completely left/right-circularly polarized emissions, respectively. [14] Generally, typical CPL-active materials consist of two major moieties: chiral nonluminescent and achiral luminescent building blocks, which self-assemble into chiral structures. The chirality can be transferred from the chiral centers to the achiral components, leading to overall CPL emission. [1] In addition, the chiral materials can exhibit other intriguing properties, such as ferroelectricity, piezoelectricity, and pyroelectricity. [15] In an attempt to obtain high-performance CPL materials, great efforts have been made based on organic−inorganic hybrid metal halides combining chiral organic molecules. [16,17] For example, enantiomorphic chiral hybrids R/S-C 6 H 15 Cl 2 NO•SbCl 5 , exhibit intense emission with a photoluminescence quantum yield (PLQY) of 71.2% and CPL activity with a g lum of 2.5 × 10 −4 . [18] We reported 1D chain-like hybrid manganese bromides, (R/S-3-quinuclidinol)MnBr 3 , having a high g lum of 2.3 × 10 −2 and a PLQY of 50.2%. [19] 0D hybrid leadtin bromides, (RR/SS-C 6 N 2 H 16 ) 2 Pb 0.968 Sn 0.032 Br 6 •2H 2 O, was reported with a g lum of 3.0 × 10 −3 and a remarkable PLQY of 100%. [20] However, there are still few reported cases of highly efficient CPL-active hybrids, where quite a lot of them suffer from a low PLQY. [21,22] To consider technical applications, it is highly important to design and construct ideal hybrid metal halides with efficient left or right CPL and high PLQY.Among the hybrid metal halides, hybrid copper halides have particularly attracted tremendous attentions, for they possess highly diverse structures, [23] magnetic properties, [24,25] and efficient luminescence. [26][27][28][29][30][31] The combination of the inorganic copper(I) iodides with organic ligands/cations generates Chiral organic−inorganic hybrid metal halide materials have shown great potential for circularly polarized luminescence (CPL) related applications for their tunable structures and efficient emissions. Here, this work combines the highly emissive Cu 4 I 4 cubane cluster with chiral organic ligand R/S-3-quinuclidinol, to construct a new type of 1D Cu-I chains, namely Cu 4 I 4 (R/S-3-quinuclidinol) 3 , crystallizing in noncentrosymmetric monoclinic P2 1 space group. These enantiomorphic hybrids exhibit long-term stability and show bright yellow emission with a photoluminescence quantum yield (PLQY) close to 100%. Due to the successful chirality transfer from the chiral ligands to the inorganic backbone, the enantiomers show intriguing chiroptical properties, such as circular dichroism (CD) and CPL. The CPL dissymmetry factor (g lum ) is measured to be ≈4 × 10 −3 . Tim...
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