Toward the refrigeration applications in flexible electronics and wearable systems, we prepared a flexible NBTWFe EC film based on the mica substrate, as shown in Figure 1____. The whole cross-sectional structure is schematically illustrated in Figure 1____, where the LNO layer serves as bottom electrode and the NBTWFe is the functional layer. The mica substrate can be easily peeled off due to its weak bonding between aluminosilicate and potassium ions layers [a,b] so as to achieve an excellent flexibility. Vividly, the cross-sectional image was investigated by FESEM and is presented in Figure 1____. The NBTWFe film is relatively dense except for some notable pinholes due to the inevitable volatilization of organic substances during the film crystallization. The LNO electrode is found to be well grown on the mica with 150nm in thickness. The NBTWFe film is about 430nm. And the sharp interface between LNO and NBTWFe film indicates a high quality of the heterostructure. The AFM measurement was adopted in a 2 ́2mm 2 region to characterize the surface morphology of the NBTWFe thin film, as shown in Figure 1____. The film possesses a quite smooth surface with average surface roughness ____ of 6.41nm and root mean square roughness ____ of 8.32nm. Figure 1____ shows the XRD pattern of the NBTWFe film grown on LNO/Mica. Note that the film shows good crystallinity with both pure perovskite phase and a preferred ____-orientation.