fig4

Figure 4. The free energy calculations for perovskite phase segregation. (A-C) The excitation intensity-dependent free energy variation at 300 K with different light intensities (η = 1/9, 1/3, 1/2); (D) The predicted phase diagram along with different light intensities at 300 K. The binodal and spinodal lines and regions are shown in blue and red, respectively. The light intensities are illustrated by greyscale shaded areas (~2-sun, 10-sun).