Potassium Ion Assisted Synthesis of Organic–Inorganic Hybrid Perovskite Nanobelts for Stable and Flexible Photodetectors

Low‐dimensional organic–inorganic hybrid perovskites with controllable morphologies are attractive for high‐performance optoelectronic devices. In particular, the 1D organic–inorganic hybrid perovskite nanowires/nanobelts are promising for flexible photodetectors due to high photoresponsivity and strain endurance capability. Herein, a novel and large‐scale synthesis of (C 4 H 9 NH 3 ) 2 PbBr 4 organic–inorganic hybrid perovskite nanobelt achieved by the potassium ions assisted controllable crystal growth during the precipitation process in solutions is reported. The obtained (C 4 H 9 NH 3 ) 2 PbBr 4 perovskite nanobelts exhibit high‐efficient photoluminescence and superior stability under ambient conditions. Furthermore, these nanobelts are used as photoresponsive materials to fabricate flexible photodetectors, which show much higher switching ratio than that of photodetectors based on (C 4 H 9 NH 3 ) 2 PbBr 4 microplatelets. Attractively, after repeated bending for 1000 times, the nanobelt‐based photodetector only shows less than 10% decay in switching ratio in contrast to at least 40% of switching ratio decay for the microplatelets‐based photodetector. The reported potassium ion assisted large‐scale synthesis of (C 4 H 9 NH 3 ) 2 PbBr 4 nanobelts paves a new avenue for the application of organic–inorganic hybrid perovskites in flexible optoelectronic devices.