Fig. 3: Mitigating cycled lattice strain through Ph-Se-Cl modification.
From: Strain regulation retards natural operation decay of perovskite solar cells
a, X-ray diffraction of the wet perovskite films (before annealing) with different amounts of Ph-Se-Cl. b, The peak ratio of α-FAPbI3/PbI2 and intermediate phase/PbI2. c, High-resolution transmission electron microscopy images of the pero-Ph-Se-Cl film. Parameters d represents the interplanar spacing. d, Structural refinement (La Bail method) of the integrated GIWAXS profile recorded from the pero-Ph-Se-Cl films. e, Normalized (Nor.) lattice parameters and calculated spontaneous strain of FAPbI3 and the pero-Ph-Se-Cl samples. Parameters εtet and εorth respectively represent the degenerate tetragonal and orthorhombic symmetry-adapted strains which emerge during the phase transitions. Parameters a, b, and c are the normalized lattice parameters of the perovskite; a0 is estimated by taking the cube root of the normalized unit cell volume. f,g, Integrated profiles obtained from in situ GIWAXS maps of the pero-Ph-Se-Cl films (f, the first cycle; g, the second cycle). h, Evolution of the unit cell volume and the peak broadening parameters for the pero-Ph-Se-Cl samples during the in situ GIWAXS measurements.
