PNNL

Abstract

We have presented a detailed analysis of phase transition kinetics and binding energy states of solution processed methylammonium lead iodide (MAPbI3) thin films prepared at ambient conditions and annealed at different elevated temperatures. The processing temperature and environmental conditions predominantly control the crystal structure and surface morphology of MAPbI3 thin films. The structural transformation from tetragonal to cubic occurs at 60C for 30 minutes annealing time while 10 minutes annelaed films posses tetragonal structure. The transformed phase is greatly intact even at higher annealing temperature of 150 C and time of 2 hours. Existence of charge transfer interaction between Pb 4f and I 3d oxidation states is quantified by the XPS spin orbit spilitting.