Scaling behavior and morphology evolution of CH3NH3PbI3 perovskite thin films grown by thermal evaporation

The growth dynamics of CH3NH3PbI3 (MAPbI3) perovskite thin films, deposited by thermal evaporation, has been investigated by atomic force microscope and height–height correlation function analysis. The unstable scaling behavior of initial perovskite films exhibiting the growth of islands, resulting in rougher film formation has been observed. After the formation of continuous film, the roughening has been characterized by analyzing the scaling exponent α ~ 0.70, growth exponent β = 0.79 ± 0.057, 1/z = 0.78 ± 0.038, and 2D fast Fourier transform. Anomalous scaling behavior of the MAPbI3 thin films and the formation of the rapid surface roughening are discovered. It is demonstrated that step-edge barrier induced mound growth may play the dominate role in the growth mechanism of MAPbI3 thin films on Si substrates. Further, the growth behavior of MAPbI3 film on ITO substrates is investigated as a comparison, and it reveals that the growth of MAPbI3 thin films is largely affected by the initial substrates underneath the growing films.