Fabrication of morphology-controlled and highly-crystallized perovskite microwires for long-term stable photodetectors

In this work, highly crystallized and lengths up to a centimeter organic-inorganic hybrid perovskite CH₃NH₃PbI₃ (MAPbI₃) microwires (MWs) have been prepared via a solution-based blade coating and slow solvent evaporation method. And a two-step growth mechanism was proposed to explain the formation and growth of the MAPbI₃ MWs. Further, the as-prepared MWs were used to fabricate photodetectors and their photoresponse characteristics were tested and detailedly analyzed. The results reveal that the devices presented stable and repeatable photocurrent responses. A high on/off photocurrent ratio of 0.84 × 10⁴, a photoresponsivity of 0.04 A/W, a specific detectivity of 0.6 × 10¹² Jones, and a fast response speed of 178/173 μs were realized in the prepared MAPbI₃ photodetectors. More importantly, even without encapsulation, the proposed photodetectors demonstrate remarkable operation stability, above 80% of the photocurrent has been retained after a long running time (50,000 s, 45–55% humidity). After 60 days storage without encapsulation in air ambient, the proposed photodetectors can be efficiently sustained, demonstrating a strong ability to resist the water and oxygen degradation, greatly superior to reference photodetectors constructed with MAPbI₃ thin films. This work opens up an exciting opportunity for using MAPbI₃ MWs for high-performance and low-cost photodetectors applications.