Next-Generation Self-Powered\nPhotodetectors using 2D Bismuth\nOxide Selenide Crystals

The concept of self-powered\nphotodetectors has attracted significant\nattention due to their versatile applications in areas such as intelligent\nsystems and hazardous substance detection. Among these, <i>p–n</i> junction and Schottky junction photodetectors are the most widely\nstudied types; however, their fabrication processes are often complex\nand costly. To overcome these challenges, we focused on the emerging\nself-powered, ultrasensitive photodetector platform based on photoelectrochemical\n(PEC) principles. This platform leverages the unique properties of\nthe emerging material bismuth oxide selenide (Bi<sub>2</sub>O<sub>2</sub>Se), which features a wide bandgap (∼2 eV) and a high\nabsorption coefficient. We utilized chemical exfoliation to obtain\nthin layers of Bi<sub>2</sub>O<sub>2</sub>Se, enabling highly efficient\nphotodetection. The device characterization demonstrated impressive\nperformance metrics, including a responsivity of 97.1 μA W<sup>–1</sup> and a specific detectivity of 2 × 10<sup>8</sup> cm Hz <sup>1/2</sup> W<sup>–1</sup>. The PEC photodetector\nalso exhibits broad-spectrum sensitivity, from blue to infrared wavelengths,\nand features an ultrafast response time of ∼82 ms and a recovery\ntime of ∼86 ms, highlighting its practical potential. Moreover,\nthese self-powered photodetectors show excellent stability in electrochemical\nenvironments, positioning them promising candidates for integration\ninto future high-efficiency devices.