Recent progress on flexible inorganic single-crystalline functional oxide films for advanced electronics

The broad spectrum of physical properties in functional oxide materials has attracted intensive research interest in recent years. In particular, freestanding thin films of single-crystalline functional oxides, as flexible and isolated forms of two-dimensional (2D) geometries, are expected to have great potential in integration with flexible and semiconductor devices. Here, we review the progress made in recent years in fabricating freestanding single-crystalline functional oxide films via chemical release methods and exfoliation methods. These freestanding films are mechanically flexible and thus allow the intrinsic effect of mechanical strain to be investigated. Using the engineering bending procedure, tuning the physical properties of these flexible oxide films has been realized. The currently made progress in studying the freestanding oxide films is expected to stimulate extensive research, from fundamental physics of two-dimensional materials to applications in advanced electronics.