A Strategy toward New Low‐Dimensional Hybrid Halide Perovskites with Anionic Spacers

Abstract

Recently, the organic-inorganic halide perovskite (OIHP) materials have received enormous attention due to their unique performances demonstrated in photovoltaic and optoelectronic devices. [1] The perovskite solar cells employing OIHP as absorber with planer structure have demonstrated the certified power conversion efficiency over 23.3%. [2] Holding this great promise, along with their solutionprocessable feature, the research on OIHP materials has been extended to the nanoscale. Both OIHP and all-inorganic halide perovskite (AIHP) nanocrystals (NCs) stand out as a new class of fluorescent light-emitting materials, showing strong quantum confinement effect. [3] Therefore, it is highly expected that the perovskite-based NCs may allow us to fabricate devices with unique photophysical, electronic, and charge transport performances in contrast to their bulk form. [4] The crystallographic dimensionality of the halide perovskite materials can be regulated by adjusting the connection patterns of the PbX 6 octahedron. Taking Cs-based AIHP as an example, the dimensionality can be modulated among 0D, [5] 1D, [6] 2D, [7] and 3D. [8] Compared with the 3D halide perovskite, the low-dimensional counterpart displays abundant structural diversity and functionality not only in halide perovskite but also in the oxide perovskite. [9] It results in improved performance by combining their merits in physiochemical and optoelectronic properties. [10] So far, various organic/inorganic cationic molecules, including ammonium, [11] amidinium, [12] imidazolium, [13] phosphonium, [14] etc., have been used as periodic spacers or ligands to inhibit the formation of 3D perovskite structure by replacing the A-site ions (e.g., Cs + , CH 3 NH 3 + , and HC(NH) 2+ ). In addition, Gemini-type bifunctional molecules with two ionic terminal groups serving as linkers between layers, such as diamine, [15] amino acid, [16] etc., have also been reported to obtain the layered 2D perovskite with extra functionalities. Recently, the 2D Pb 2 X 2 (HDA) (X = F, Cl, and Br) reported by Fei and coworkers indicates that Pb 2+ and halide ions can form a [PbX] − inorganic layer between the organic anionic spacers. [17] However, there have been limited investigations on organic anions serving as the spacers to construct low-dimensional halide perovskite.The low-dimensional halide perovskites have received enormous attention due to their unique photovoltaic and optoelectronic performances. Periodic spacers are used to inhibit the growth of 3D perovskite and fabricate a 2D counterpart with layered structure, mostly based on organic/inorganic cations. Herein, by introducing organic anions (e.g., pentanedioic acid (PDA) and hexanedioic acid (HDA) simultaneously), leaf-shaped (Cs 3 Pb 2 Br 5 ) 2 (PDA-HDA) microplates with low-dimensional structure are synthesized. They also exhibit significant photoluminescence (PL) centered at 540 nm with a narrow emission peak. The synthesis of single crystals of Pb(PDA) and Pb(HDA) allows to further clarify the crystal struct...

Designing guanidine-based lead-free hybrid indium perovskites with highly efficient intrinsic broadband emissions

“…Recently, a series of lead-based OIMHs with intriguing photophysical properties and high luminescence stability has been reported. [1][2][3][4][5][6][7][8] The poor environmental stability and substantial toxicity of Pb 2+ ions in lead halide perovskites hinder their large-scale industrial and commercial utilization. In light of these challenges, the exploration of novel, environmentally friendly, highly efficient, and stable OIMH luminescent materials has become increasingly imperative.…”