Enhanced responsivity of solution-processed perovskite heterojunction photodetector via combination of vertical type structure and optical fiber coupling

Solution-processed perovskite heterojunction photodetectors have attracted widespread attention due to their low-cost, large-area processing techniques; however, they still suffer from low responsivity. In this work, we propose and demonstrate a vertical type FA0.4MA0.6PbI3/Cu2O heterojunction photodetector integrated with a D-shaped optical fiber coupling scheme to enhance responsivity. Microstructural characterization reveals that Cu2O contributes to enhancing light absorption and accelerating photoexcited carrier transport. Compared with the planar type, the vertical type FA0.4MA0.6PbI3/Cu2O photodetector achieves an order-of-magnitude improvement in responsivity. Experimental results indicate that the vertical type FA0.4MA0.6PbI3/Cu2O optical fiber device has a high built-in electric field and a light–matter interaction, which facilitates photocarrier transport, separation, and collection. Additionally, under illumination of 21.3 μW 650 nm light at a bias voltage of −1.5 V, photodetectors based on the vertical type FA0.4MA0.6PbI3/Cu2O and D-shaped fiber exhibit superior photoelectric performance, including a high responsivity of 22.1 A/W, a maximum photocurrent of 15.1 μA, an external quantum efficiency of 4.22 × 103%, and a detectivity of 7 × 1010 Jones. The responsivity of vertical type FA0.4MA0.6PbI3/Cu2O optical fiber integrated photodetector is not only superior to that of the planar type device in this work but also exceeds that of the recently reported solution-processed perovskite heterojunction photodetector. The research results provide a feasible strategy for designing the solution-processed perovskite heterojunctions for low-cost, high-performance photonic devices.