Chiral Metal Halide Perovskites: Focus on Lead-Free Materials and Structure-Property Correlations

Abstract

Hybrid organic-inorganic perovskites (HOIPs) are promising materials in several fields related to electronics, offering long carrier-diffusion lengths, high absorption coefficients, tunable band gaps, and long spin lifetimes. Recently, chiral perovskites have attracted huge interest thanks to the possibility of further widening the applications of HOIPs. Chiral materials, being intrinsically non-centrosymmetric, display several attractive physicochemical properties, including circular dichroism, circularly polarized photoluminescence, nonlinear optics, ferroelectricity, and spin-related effects. Recent studies have shown that chirality can be transferred from the chiral organic ligands into the inorganic perovskite framework, resulting in materials combining the advantages of both chirality and perovskite superior optoelectronic characteristics. As for HOIPs for photovoltaics, strong interest is currently devoted towards the development of lead-free chiral perovskites to overcome any toxicity issue. While considering the basic and general features of chiral HOIPs, this review mainly focuses on lead-free materials. It highlights the first attempts to understand the correlation between the crystal structure characteristics and the chirality-induced functional properties in lead and lead-free chiral perovskites.

Keywords: chiral materials; metal halide perovskites; optical properties; structure of solids.

Figure 1

Structure of Chiral Perovskites: (a) 1D structure; (b) 2D structure; (c) 3D structure. Reprinted with permission from Ref. [4]. 2021, Wiley.

Figure 2

(a) Structure of (R-MPEA)₂SnBr₆; (b) SHG measurement; (c) UV-Vis and (d) CD spectra. Reprinted with permission from Ref. [17]. 2021, Wiley.

Figure 3

(a) Structure of (R/rac-MBA)₄Bi₂I₁₀; (b) UV-Vis spectra; (c) CD spectra. Reprinted with permission from Ref. [18]. 2022, American Chemical Society.

Figure 4

(a) Structure of (R/S-MBA)₄Bi₂Br₁₀; (b) UV-Vis and CD spectra of (R/S-MBA)₄Bi₂Br₁₀; (c) UV-Vis and CD spectra of R/S-MPA)₂BiBr₅. Reprinted with permission from Ref. [19]. 2023, Wiley.

Figure 5

Structure of [R-β-MPA]₄AgBiI₈ where BiI₆ octahedra, purple; AgI₆ octahedra, blue. Reprinted with permission from Ref. [20]. 2021, Wiley.

Figure 6

(a) CD spectra; (b) UV-Vis spectra. Reprinted with permission from Ref. [20]. 2021, Wiley.

Figure 7

(a–f) Evolution of ferroelastic domains under the variation of temperature for [R-EQ]PbI₃ with the scale bar of 100 μm. Reprinted with permission from Ref. [21]. 2022, American Chemical Society.

Figure 8

Structure of (R/S-MBA)₂PbI₄. Reprinted with permission from Ref. [23]. 2019, American Chemical Society.

Figure 9

Normalized absorption (a) and steady-state PL spectra (b) of (R-MBA)₂PbI₄, (S-MBA)₂PbI₄, and (rac-MBA)₂PbI₄ microplates obtained by mechanical exfoliation. (c) CD spectra of (R-, S-, and rac-MBA)₂PbI₄ films. Reprinted with permission from Ref. [23]. 2019, American Chemical Society.

Figure 10

(a) Structure of [(R)-1-(4-F)PEA]₄[Sb₂Cl₁₀]; (b) UV-Vis spectra of all compounds. Reprinted with permission from Ref. [24]. 2020, American Chemical Society.

Figure 11

Structure of compounds (R/S/rac-MBA)₂SnI₄ [25]. Reprinted with permission from Ref. [25]. 2020, American Chemical Society.

Figure 12

(a) CD spectra of (R/S/rac-MBA)₂SnI₄; (b) CD spectra of (R/S/rac-MBA)₂Pb_1−XSn_xI₄. Reprinted with permission from Ref. [25]. 2020, American Chemical Society.

Figure 13

UV–vis–NIR absorption spectra (a) and CD spectra (b) of (R-MPEA)₂CuCl₄, (S-MPEA)₂CuCl₄, and (rac-MPEA)₂CuCl₄. Reprinted with permission from Ref. [26]. 2020, American Chemical Society.

Figure 14

CD spectra of the R- (blue), S- (red), and rac- (black) fabricated HOIPs films including (MBA)₂PbI₄, (FMBA)₂PbI₄, (ClMBA)₂PbI₄ (BrMBA)₂PbI₄, and (IMBA)₂PbI₄ series. Reprinted with permission from Ref. [28]. 2021, Wiley.