Hybrid halide perovskites have clearly made a spectacular appearance in the field of solar absorber materials [1]. With solar cell efficiencies steeply rising, there are some important shortcomings, notably their stability, lead content and fundamental understanding.
Applying advanced X-ray characterization methods like X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) it is possible, to shed light on the static and dynamic structure of hybrid halide perovskites as well as the early stage of their growth in solution, contributing to a better understanding of the fundamental materials properties.
The presentation will focus on
(i)    The temperature dependent phase behaviour of halide perovskites in the system MAPbX₃ – FAPbX₃ – CsPbX₃ (MA-methylammonium-[CH₃NH₃]⁺, FA-formamidinium-[CHN₂H₄]⁺ and X=I, Br) was revealed by in-situ temperature dependent XRD. 
(ii)    Employing high resolution anomalous single crystal X-ray diffraction, we elucidate as to whether MAPbI₃, the signature compound of the hybride halide perovskite materials’ class, is centrosymmetric or not [3]. This question is of great importance as it has tremendous implications on its physical properties [4].
(iii)    Despite hybrid halide perovskites’ popularity, the growth mechanism of such crystals in solution is still unknown. We applied SAXS to investigate precursor solutions of different hybride halide perovskites in different common solvents used to synthesize thin films.
(iv)    We applied combined temperature-dependent synchrotron-XRD and Pb-L3 edge extended X-ray absorption fine structure (EXAFS) to analyze the anharmonicity of the lead−halide bond in chloride-substituted MAPbI₃ [5].
With this overview of applying different synchroton X-ray based analytical methods for an in-depth investigation of fundamental properties of hybride halide perovskites, the power as well as the complementartity of the techniques will be demonstrated.
[1] e.g. M. A Green, A. Ho-Baillie and H. J. Snaith, Nat. Photonics, 2014, 8, 506.
[2] F. Lehmann et al., RSC Adv., 2019, 9, 11151.
[3] J. Breternitz et al., Angew. Chem. Int. Ed., 2020, 59, 424.
[4] e.g. K. Frohna et al., Nature Commun., 2018, 9, 1829.
[5] G. Schuck et al., J. Phys. Chem. C, 2022, 126, 5388.