Crystal structures of perovskite halide compounds used for solar cells

Takeo Oku

doi:10.1515/rams-2020-0015

Abstract

AbstractThe crystal structures of various types of perovskite halide compounds were summarized and described. Atomic arrangements of these perovskite compounds can be investigated by X-ray diffraction and transmission electron microscopy. Based on the structural models of basic perovskite halides, X-ray and electron diffractions were calculated and discussed to compare with the experimental data. Other halides such as elemental substituted or cation ordered double perovskite compounds were also described. In addition to the ordinary 3-dimensional perovskites, low dimensional perovskites with 2-, 1-, or 0-dimensionalities were summarized. The structural stabilities of the perovskite halides could be investigated computing the tolerance and octahedral factors, which can be useful for the guideline of elemental substitution to improve the structures and properties, and several low toxic halides were proposed. For the device conformation, highly crystalline-orientated grains and dendritic structures can be formed and affected the photo-voltaic properties. The actual crystal structures of perovskite halides in the thin film configuration were studied by Rietveld analysis optimizing the atomic coordinates and occupancies with low residual factors. These results are useful for structure analysis of perovskite halide crystals, which are expected to be next-generation solar cell materials.

Highlights

One of the most serious problems in natural environment is global warming, which has been caused by generation of carbon dioxides (CO2)
The crystal structures of various types of perovskite halide compounds were summarized and described. Atomic arrangements of these perovskite compounds can be investigated by X-ray diffraction and transmission electron microscopy
The energy gap widens with lowering temperature from the first principle calculation, and the energy gaps were measured to be ~1.5 eV, which is close to the adequate energy gap value as that of solar cell materials

Summary

Introduction

One of the most serious problems in natural environment is global warming, which has been caused by generation of carbon dioxides (CO2). The energy gap widens with lowering temperature from the first principle calculation, and the energy gaps were measured to be ~1.5 eV, which is close to the adequate energy gap value as that of solar cell materials Both microstructures and crystal structures of the perovskite halide compounds can be investigated using XRD. Several TEM analysis studies on the perovskite halide compounds for solar cells have been reported, and the crystal structures and nanostructures were investigated by the structural images and electron diffraction patterns [118, 165, 166]. Since the MA2KBiCl6 has a rhombohedral symmetry, the diffraction patterns are completely different from other double perovskite halides with cubic symmetry Some of these double perovskite elpasolite compounds are expected to apply to Pb-free solar cells [199,200,201], and the energy gaps have been reported [187, 199].

C24 H35 S8 N4 PbI5

Findings

Conclusion