Self‐Powered n‐SnO 2 /p‐CuZnS Core–Shell Microwire UV Photodetector with Optimized Performance

Herein, a single‐crystal SnO 2 microwire photodetector (PD) is demonstrated with a fast response speed owing to a low concentration of point defects. However, the presence of surface defects (e.g., oxygen vacancies) still limits its optoelectronic performance. To further improve the photoresponse of such device, a core–shell p–n junction is constructed by simply coating a new p‐type transparent conductive (CuS) 0.35 :(ZnS) 0.65 nanocomposite film (CuZnS) on n‐type SnO 2 microwire. As a result, not only the surface of SnO 2 is modified, but also a space charge depletion region is formed at the interface, leading to an enhanced on‐off ratio of ≈1.3 × 10 3 and a faster speed of 45 µs/1.17 ms (rise time/decay time) in comparison with the plain SnO 2 microwire PD (on‐off ratio of 30, response speed of ≈100 µs/1.5 ms). Besides, the n‐SnO 2 /p‐CuZnS core–shell microwire could steadily work as a self‐powered UV PD, with a maximum responsivity of 1.6 mA W −1 (at 0 V) and detectivity of 5.41 × 10 11 Jones (at 0.05 V) toward 315 nm, which suggests its great potentials as a high‐performance self‐powered UV photodetector.