Fig. 1. In-situ XRD spectrum of MAPbI3 under different temperature condition (a) phasetransition from tetragonal to cubic at 25~35℃, (b)phase separation PbI2/MAI at 125~135℃, (c) peak deconvolution of the cubic structure (100) spectrum at 135~140℃, and (d) peak deconvolution of the tetragonal structure (200) spectrum at 28~28.5℃.
Fig. 2. EELS spectrum measured by electron current value (a) EELS spectrum of 0.2, 0.5, 1.0, 5.0, and 10.0 nA screen current, (b) plasmon peak shift of about 2.8 eV in the low loss region, and (c) temperature change of calculated by average electron energy loss value, specimen properties and TEM condition.
Fig. 3. Effect of MAPbI3 structure on electron current and specimen temperature (a), (d) the high-resolution TEM images and the FFT patterns in the process of phase change from tetragonal to cubic at 31.95℃, (b), (e) cubic to trigonal at 128.5℃, and (c), (f) change of phase of PbI2 ring pattern density at 150℃.