X-ray diffraction of photovoltaic perovskites: Principles and applications

Abstract

Solar cells based on organic–inorganic hybrid perovskite materials have emerged as the most efficient next-generation thin-film solar cells within just a decade of research and show great promise for commercialization. As control of the thin-film microstructure of the perovskite layer is a key factor enabling high photovoltaic efficiency, good stability, and successful up-scaling of high-quality perovskite thin films for commercialization, a reliable and accurate characterization of the thin-film microstructure is paramount. X-ray diffraction (XRD)-based techniques, including conventional laboratory-based XRD and synchrotron-based grazing-incidence wide-angle x-ray scattering, are widely used to probe the microstructure of photovoltaic perovskite thin films. Nevertheless, it is common for these XRD experiments to be poorly executed and diffraction data to be improperly interpreted. This review focuses on principles of XRD techniques and their application for the characterization of the perovskite thin-film microstructure. Fundamentals of XRD techniques are presented with a strong emphasis on best practices in data collection and analysis. Approaches for the reliable and accurate extraction of microstructural information from diffraction data are discussed, including the need for simulating diffraction patterns. Applications of XRD techniques in characterizing perovskite thin films are demonstrated for both three-dimensional and layered hybrid perovskites, covering various microstructural aspects including phase identification and quantification, texture analysis, microstrain, and macrostrain as well as in situ and operando characterization. The additional subtleties and complexities associated with the XRD characterization of layered hybrid perovskites due to a more complex thin-film microstructure are discussed. Common mistakes and pitfalls that lead to misinterpretation of diffraction data are also highlighted.

Nano-optical designs for high-efficiency monolithic perovskite–silicon tandem solar cells

“…2g ). It is known that the impact of crystallite orientation on the carrier dynamics of layered perovskite is crucial; however, this relation has been the subject of controversy for three-dimensional perovskite 41 . There are both research reports claiming that the improved crystallite orientation contributes to improved optoelectronic properties 33 , 42 , 43 , and those claiming that there is no clear correlation 44 .…”

Rationalizing the Effect of Polymer-Controlled Growth of Perovskite Single Crystals on Optoelectronic Properties

“…The PEG- and PS-based SCs showed peaks at 27.67 and 27.74° corresponding to (004) facet, 27.96 and 28.03° corresponding to (220) facet, 24 and 23.05° corresponding to (211) facet, and 39.95 and 40.02° corresponding to (224) facet, respectively. The results suggest that these SCs have high phase purity and the polymers do not influence the perovskite phase . To check the crystallinity of the as-grown crystals, we calculated the full width at half-maximum (fwhm) of these peaks (Figure b).…”

“…The results suggest that these SCs have high phase purity and the polymers do not influence the perovskite phase. 39 To check the crystallinity of the as-grown crystals, we calculated the full width at half-maximum (fwhm) of these peaks ( Figure 1 b). The fwhm of the (224) diffraction peak is found to be 0.1378 for MAPbI 3 , which is higher than that of PEG-assisted SCs (0.0780) and PS-assisted SCs (0.0787).…”

Spontaneous Formation of a Ligand-Based 2D Capping Layer on the Surface of Quasi-2D Perovskite Films

“…The crystal symmetry of these two directions leads to the identical appearance of simulated GI-WAXS patterns (Figure S6). For small- n 2D RPPs, BA 2 MA 2 Pb 3 I 10 ( n = 3) was selected for the GI-WAXS pattern simulation. In contrast to the large- n RPPs, the GI-WAXS patterns of the <010> horizontally (<010> direction normal to the substrate) and vertically (<101> normal to the substrate) oriented small- n RPP films are quite different from each other.…”