Photonic Array Integrated Dual-Phase CsPbBr ₃ –CsPb ₂ Br ₅ Nanosheets for Enhanced Photodetection and Directional Light Emission Applications

Nanostructured photonic architectures enable precise control of light–matter interactions through field confinement and optical resonances, enabling high-performance optoelectronic devices. At the same time, metal halide perovskites have emerged as a promising photoactive material for these devices due to their excellent optoelectronic properties. In this perspective, we report a hybrid photonic perovskite platform by integrating dual-phase CsPbBr 3 –CsPb 2 Br 5 nanosheets with a TiO 2 -coated two-dimensional (2D) photonic array for enhanced photodetection and directional light emission. This configuration offers Guided Mode Resonance (GMR) enhanced optical absorption and electric-field confinement within the perovskite layer. The hybrid photodetector exhibits an enhanced photocurrent, increasing from 3 nA for the planar device to 40 nA for the array-integrated device at 405 nm laser excitation, resulting in a 1000% enhancement factor and a light-on/off ratio of around 10 3 . Additionally, the hybrid device exhibits a maximum responsivity of 25.0 mA/W and a detectivity of 6.0 × 10 9 Jones at the resonant GMR wavelengths, underscoring the effectiveness of guided-mode-assisted field confinement. Furthermore, the designed photonic array exhibits enhanced directional emission, a 10-fold increase in emission intensity, and a Purcell factor of 2.27 by coupling the spontaneous emission from CsPbBr 3 –CsPb 2 Br 5 excitons to the GMR modes supported by the array. These findings establish a scalable, low-loss strategy for integrating photonic-perovskite architectures into the development of advanced optoelectronic devices.