Perovskite Microwire Crystals Encapsulated by Nano‐Grating Structured Small Molecular Film for Polarization‐Sensitive and Highly Stable Photodetectors

Perovskites have emerged as promising materials for high‐performance photodetectors owing to their strong optical absorption, high carrier mobility, and long carrier diffusion lengths. However, their intrinsic instability remains a major obstacle to practical applications. Here, MAPbI 3 microwires are encapsulated with a nano‐grating structured 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8BTBT) film. The hydrophobic nano‐grating layer markedly enhances stability, enabling the device to retain 94.0% of its initial photocurrent after 80 days in air. Benefiting from improved light harvesting and carrier transport, the device achieves a responsivity of 1.35 × 10 4 A W −1 and a detectivity of 4.85 × 10 11 Jones. Moreover, the combined anisotropy of the MAPbI 3 microwire arrays and the C8BTBT nano‐grating yields strong polarization sensitivity with a dichroic ratio ( I max / I min ) of 1.87.