Triangular Micro‐Grating via Femtosecond Laser Direct Writing toward High‐Performance Polarization‐Sensitive Perovskite Photodetectors

Abstract Thanks to attractive properties, such as defect tolerance, broad bandgap tunability, high quantum yields, and large absorption coefficient, perovskites have emerged as a star material in the past decade. Meanwhile, optical nano/microstructures made of perovskites offer a facile and efficient strategy to improve light‐harvesting performance and sensitivity of polarization. However, there is no low‐cost, high‐accuracy, and reproducibility technique for large‐scale fabrication of perovskite nano/microstructures. Here, femtosecond laser direct writing technique is introduced to fabricate FAPbI₃ perovskite micro‐grating. Based on precise spatial and power control of femtosecond laser, micro‐grating with different structure parameters (period and depth) can be processed and investigated. Triangular micro‐grating of perovskite exhibits excellent emission properties (up to 67 times enhancement) owing to low reflectance and high absorption intensity. Strikingly, the outstanding performance of perovskite triangle grating photodetectors is obtained. The responsivity and detectivity reach 11.7 A W⁻¹ and 7.8 × 10¹² Jones, which are ≈3 and 12 times larger than the control devices; they also exhibit lower noise and decent polarization sensitivity. Taking the advantages of low cost, high accuracy, and reproducibility, the femtosecond laser direct writing technique endows perovskite materials with micro‐photonic concept and remarkably enhances the devices’ performance.