Probing local structural disorder and its stabilizing effect in doped CsPbI3 perovskite using in situ XAFS

Here, we aim to improve the black phase stability of CsPbI3 at ambient conditions without compromising the optoelectronic properties by controlled doping-induced lattice strain. Incorporation of the dopant can occur via two pathways: by substitution with the B-site metal or by occupation of interstitial sites/grain boundary in the lattice. Depending on the incorporation type, the cationic/anionic charge state and occupancy would be modified to neutralize the overall system, leading to distinct changes in the lattice and band structures creating measurable structural and optical signatures. For the doping case it is important to know where the dopant is sitting and how it is helping to reduce the spontaneous strain, which call for systematic local atomic structure and electronic state characterization of Cs and I atom in series of Bi3+ doped CsPbI3 to investigate the underlying operation and phase degradation mechanisms. Therefore, high resolution XAFS is mandatory for all the systems.