Polarization‐Sensitive and Stable Near‐Infrared Photodetector Enabled by Up‐Conversion Integrated MAPbBr ₃ Microwires

Broadband photodetection with high sensitivity in the near‐infrared (NIR) range remains a bottleneck for traditional perovskite materials because of their intrinsic bandgap limitations. To address this issue and enable efficient NIR‐to‐visible photon conversion, we developed a MAPbBr 3 microwire crystal (MWC) photodetector incorporating up‐conversion particles (UCPs). This design extends the sensitivity of the device to 980 nm, achieving a responsivity (R) of 10.3 A/W, detectivity (D * ) of 2.6 × 10 11 Jones, and an external quantum efficiency (EQE) of 1310% under a bias voltage of 1 V. The photodetector retains 55% of its initial performance after 171 d of air exposure and 82% of its initial performance under 180° bending, demonstrating robust mechanical flexibility. In addition, it exhibits polarization sensitivity with I max /I min of 1.73. These results establish the UCP‐integrated MAPbBr 3 MWCs as a stable, flexible, and polarization‐sensitive platform for NIR photodetection and optoelectronic applications.