Unraveling All‐Inorganic CsPbI 3 and CsPbI 2 Br Perovskite Thin Films Formation – Black Phase Stabilization by Cs 2 PbCl 2 I 2 Addition and Flash‐Annealing

Edouard Breniaux (1) , Pascal Dufour (1) , Sophie Guillemet-Fritsch (1) , Christophe Tenailleau (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Phase formation and transformation of 3D inorganic halide perovskites CsPbI3 and CsPbI2Br were investigated by in-situ X-ray diffraction (XRD) in nitrogen or air from 30 °C up to 320 °C. Thin films were obtained by spin-coating of a liquid solution of salt precursors dissolved in DMSO under normal conditions. XRD data analysis, by using the Le Bail method, evidenced for the first time, to our knowledge, the spontaneous crystallization of black orthorhombic γ phase at ambient temperature, for both 3D perovskite phases. For once, this black γ phase could be studied upon heating. It transforms to the black tetragonal β and cubic α phases. The reverse transitions were also evidenced upon cooling. The influence of the all-inorganic 2D Cs2PbI2Cl2 material addition over the black phase stability was unprecedently analyzed by in-situ XRD. The mixture of the 3D and 2D phases, or mix [3D+2D], exhibits an improved stability of the black phase compared to the single 3D phase, and tends to induce highly oriented thin films and increased compactness, probably due to chemical insertion or anchoring. Finally, flash-annealed thin films at various temperatures (RT

Mots clés: Cs2PbCl2I2; Halide perovskites; In-situ X-ray diffraction; Thin films; CsPbI3 and CsPbI2Br

Domaines: Sciences de l'ingénieur [physics]; Chimie

Edouard Breniaux, Pascal Dufour, Sophie Guillemet-Fritsch, Christophe Tenailleau. Unraveling All‐Inorganic CsPbI 3 and CsPbI 2 Br Perovskite Thin Films Formation – Black Phase Stabilization by Cs 2 PbCl 2 I 2 Addition and Flash‐Annealing. European Journal of Inorganic Chemistry, 2021, 2021 (30), pp.3059-3073. ⟨10.1002/ejic.202100304⟩. ⟨hal-03851384⟩