Hybrid Double Perovskite Derived Halides Based on Bi and Alkali Metals (K, Rb): Diverse Structures, Tunable Optical Properties and Second Harmonic Generation Responses

Abstract

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.

In/Bi-based Direct- and Indirect-Gap Hybrid Double-Perovskite-Derived 1D Halides with Near-Unity Quantum Yield via Sb3+ Doping

“…The optical band gaps, determined by extrapolating the absorbing edge to the linear part, are 4.5 eV for (Mor) 2 KInCl 6 , 3.6 eV for (Mor) 2 KInBr 6 , 3.3 eV for (Mor) 2 KBiCl 6 , 3.0 eV for (Mor) 2 KBiBr 6 , 4.9 eV for (Mor) 2 NaInCl 6 , and 3.7 eV for (Mor) 2 NaInBr 6 (Figure a–c and Table ). These band gaps are comparable with other reported materials, such as (PMA) 3 InBr 6 (3.78 eV), (PBA) 4 InBr 7 ·H 2 O (4.05 eV, (PBA) + = C 6 H 5 (CH 2 ) 4 NH 3 + ), (PBA) 4 BiBr 7 ·H 2 O (3.52 eV), and [(ArNH 3 ) 3 (BiBr 6 )] (2.92 eV, Ar = 2,6-diisopropylphenyl). − Comparing (Mor) 2 NaInBr 6 vs (Mor) 2 KInBr 6 , they have very similar band gaps, which indicate that the A -site metal and the structural connectivity have little effect on the band gaps . However, in the case of (Mor) 2 NaInCl 6 vs (Mor) 2 KInCl 6 , the difference in the band gap is pronounced (∼0.5 eV), which hints that the chlorides are more sensitive in terms of structure and composition.…”

“…The phase purity was confirmed via powder X-ray diffraction (PXRD) for the same features of the samples and simulation results (Figures S1–S3). We have previously reported the structure of (Mor) 2 KBiBr 6 , whereas the other structures are all new and are first reported here. These compounds have unique 1D structures constituted by [K X 4 O 2 ] and [ BX 6 ] octahedron units.…”

“…Morpholine was chosen as the organic cationic ligand because of its structure containing an oxygen atom for coordination with the alkali metal, and the nitrogen on the ring could be protonated for charge balance. The sp 3 oxygen atoms in organic cationic ligands, such as ethanolammonium (EA) and methyl-2-hydroxyethylammonium (MEA), have been shown to participate in the constitution of the metal halide octahedra and generate large distortions . Single-crystal X-ray diffraction (SCXRD) analyses revealed that the (Mor) 2 K BX 6 ( X = Cl, Br) are isostructural and crystallize in the monoclinic space group C 2/ c , whereas (Mor) 2 NaInCl 6 and (Mor) 2 NaInBr 6 crystallize in the monoclinic space group P 2/ c and P 2 1 / c , respectively (detailed crystallographic data are given in Tables S1–S3).…”

Phase Transitions and Dynamics in Mixed Three- and Low-Dimensional Lead Halide Perovskites

“…The mixing effects and the dielectric response are also significantly understudied in the related lead-free families of hybrid materials such as tin halides, ,, antimony halides, , bismuth halides, − tellurium halides, and double (e.g., Ag/Bi) perovskites. − Many of these compounds undergo structural phase transitions related to the ordering-disordering phenomena and ferroelectric properties. Thus, one can expect a formation of similar frustrated phases in these materials upon mixing.…”

Extended Honeycomb Metal Chloride with Tunable Antiferromagnetic Correlations

“…Metal-halide perovskites have garnered significant interest as a versatile class of semiconductors due to their chemical tunability and superior photophysical properties. − However, persistent concern regarding lead toxicity has prompted researchers to explore lead-free alternatives. Several lead-free metal-halide perovskites have emerged as promising candidates, including vacancy-ordered double perovskite (A 2 MX 6 , e.g., A = Cs + , K + ; M = Sn 4+ and Te 4+ ; X = halide ions), , double perovskite (A 2 M I M III X 6 , e.g., A = Cs + , Rb + ; M I = Ag + and Na + ; M III = Bi 3+ , Sb 3+ , and In 3+ ; X = halide ions), − and vacancy-ordered triple perovskite (A 3 M 2 X 9 , e.g., A = K + , Cs + ; M = Bi 3+ and Sb 3+ ; X = halide ions). − However, most of the current research is focused on nonmagnetic systems. In comparison to the extensively studied optoelectronic properties, the investigation of magnetic properties remains relatively limited. − Introducing transition metals into perovskite structures represents a promising approach for altering optoelectronic properties and introducing cooperative magnetism. , …”