Research progress of applications of freestanding single crystal oxide thin film

Flexible electronics are of great interest to researchers because of their wide applications such as information storage, energy harvesting and wearable device. To realize extraordinary functionalities, freestanding single crystal oxide thin film is applied due to its super elasticity, easy-to-transfer, and outstanding ferro/electric/magnetic properties. Owing to state-of-art synthesis methods, functional oxide film of various materials can be obtained in freestanding phase, which eliminates the restrictions from growth substrate and can be transferal to other flexible layers. In this paper, we firstly introduce wet etching and mechanical exfoliation methods applied to prepare freestanding single crystal oxide thin film, then review their applications in ferroelectric memory, piezoelectric energy harvester, dielectric energy storage, correlated oxide interface, and novel freestanding oxide structure. Summary of recent research progress and future outlooks are finally discussed.