High stability visible-light photoresponse of flexible heterostructures based on LaCoO3 epitaxial films

Abstract

The research of high-speed photodetector and high-speed optical receiver garners significant attention due to their indispensable properties in many fields including high-temperature event monitoring, security, and ad hoc network wireless communication. Inorganic perovskite oxides LaCoO3 films showcase an extensive prospect in this area owing to their remarkable photoconductive effect. Up to present, however, LaCoO3 films are mostly grown on rigid instead of flexible substrates, greatly limiting their applications to wearable optoelectronic sensors. In this work, we fabricated some flexible LaCoO3 thin films to study their photoresponse. By inserting SrTiO3 and BaTiO3 as buffer layers, we find that LaCoO3 thin films could epitaxially grow on the fluorphlogopite surface and show a stable photoresponse to visible-light. Nevertheless, we also found that the epitaxial strain and the content of surface-adsorbed oxygen could impact the photoconductivity. The mechanical strain generated by bending the fluorphlogopite substrate has been confirmed to has a tunable effect on the photoresponse. Moreover, with the fatigue tests of 105 bending cycles, the flexible LaCoO3 thin films maintain a good photoresponse without any essentially weakening, proving a superior mechanical durability and stability. This work not only indicates the feasibility of the LaCoO3 films applied for flexible photodetectors but also opens a path for other perovskite films applications for flexible substrate.