Structural phase transition, electrical and semiconducting properties in a lead‐free 2D hybrid perovskite‐like compound: [Cl‐(CH 2 ) 2 ‐NH 3 ] 2 [CuCl 4 ]

Structural Features in Some Layered Hybrid Copper Chloride Perovskites: ACuCl4 or A2CuCl4

We present three new hybrid copper(II) chloride layered perovskites of generic composition ACuCl₄ or A₂CuCl₄, which exhibit three distinct structure types. (m-PdH₂)CuCl₄ (m-PdH₂²⁺ = protonated m-phenylenediamine) adopts a Dion-Jacobson (DJ)-like layered perovskite structure type and exhibits a very large axial thermal contraction effect upon heating, as revealed via variable-temperature synchrotron X-ray powder diffraction (SXRD). This can be attributed to the contraction of an interlayer block, via a slight repositioning of the m-PdH₂²⁺ moiety. (3-AbaH)₂CuCl₄ (3-AbaH⁺ = protonated 3-aminobenzoic acid) and (4-AbaH)₂CuCl₄ (4-AbaH⁺ = protonated 4-aminobenzoic acid) possess the same generic formula as Ruddlesden-Popper (RP) layered perovskites, A₂BX₄, but adopt different structures. (4-AbaH)₂CuCl₄ adopts a near-staggered structure type, whereas (3-AbaH)₂CuCl₄ adopts a near-eclipsed structure type, which resembles the DJ rather than the RP family. (3-AbaH)₂CuCl₄ also displays static disorder of the [CuCl₄]_∞ layers. The crystal structures of each are discussed in terms of the differing nature of the templating molecular species, and these are compared to related layered perovskites. Preliminary magnetic measurements are reported, suggesting dominant ferromagnetic interactions.

A Review on Lead-Free Hybrid Halide Perovskites as Light Absorbers for Photovoltaic Applications Based on Their Structural, Optical, and Morphological Properties

Despite the advancement made by the scientific community in the evolving photovoltaic technologies, including the achievement of a 29.1% power conversion efficiency of perovskite solar cells over the past two decades, there are still numerous challenges facing the advancement of lead-based halide perovskite absorbers for perovskite photovoltaic applications. Among the numerous challenges, the major concern is centered around the toxicity of the emerging lead-based halide perovskite absorbers, thereby leading to drawbacks for their pragmatic application and commercialization. Hence, the replacement of lead in the perovskite material with non-hazardous metal has become the central focus for the actualization of hybrid perovskite technology. This review focuses on lead-free hybrid halide perovskites as light absorbers with emphasis on how their chemical compositions influence optical properties, morphological properties, and to a certain extent, the stability of these perovskite materials.