Highly flexible and stable perovskite/microbead hybrid photodetectors with improved interfacial light trapping

Organic-inorganic halide perovskites are considered as a core material in optoelectronics. Particularly, perovskite-based photodetectors are promising devices for sensing and imaging applications. Their two-terminal structure provides advantages in terms of fabrication, mechanical flexibility, and reproducibility. However, due to their low responsivity, they require high driving voltages (>5 V). Here, we propose a simple procedure for the design of high-performance, low-power, and flexible perovskite photodetectors by employing an assembled polymeric microbead monolayer. A large-area photonic crystal comprising transfer-printed polystyrene (PS) beads on poly(methylmethacrylate) (PMMA)/perovskite layers confines the electromagnetic field in perovskite. The significant increase in the photoluminescence characteristics of perovskite improves the responsivity, detectivity, and noise equivalent power to over 8.5 times. The polarization-insensitive light absorption of perovskite by the PS bead layer promotes excellent omnidirectionality with respect to the incident light at different angles. Furthermore, the mechanical durability of the flexible devices at a submillimeter bending radius (0.2 mm) is significantly improved by employing PMMA/PS layers. The resulting device performance exhibits excellent retention of 81.5% after 20 bending cycles. The proposed approach in the design of versatile micro-optical structures on perovskite paves the way in realizing highly deformable and efficient perovskite-based optoelectronics.