Improving the performance of ultra-flexible perovskite photodetectors through cation engineering

High performance ultra-flexible lightweight perovskite photodetectors have promising applications on a variety of substrates, including those used on unmanned aerial vehicles. Herein, we report on a facile method to improve the performance of perovskite photodetectors on flexible ultrathin (50 μm) polyimide substrates by tuning the composition with different ratios of cations. In the presence of lead thiocyanate, the introduction of a certain amount of formamidinium could sufficiently enhance the quality of methylammonium lead triiodide perovskite film, with prolonged carrier lifetime. A perovskite photodetector with a response time of ton = 89 ms and toff = 47 ms is achieved with a very simple device architecture. In addition, our flexible photodetectors maintain good performance after rigorous folding and bending, demonstrating excellent mechanical properties, which could be very useful for a variety of applications.