CsBr- and H₂O-Enhanced CsPbI₂Br for UV–NIR Dual-Mode Photodetector with High Responsivity

Ultraviolet–visible–near-infrared broad-band PDs have attracted great attention for imaging systems and optical communications. Previous UV–NIR PDs have mainly worked in a single band. UV–NIR dual-modal detectors, which maintain a greater light response through nonlinear light absorbance in the second mode, remain to be explored. Here, a CsPbI2Br dual-mode PD is reported for the first time. The light absorption, phase stability, and chemical stability of CsPbI2Br are enhanced by CsBr and H2O. The device shows (UV–vis)/NIR absorption through one-photon and two-photon absorption. The CsPbI2Br PD has excellent (UV–vis)/NIR dual-mode detection performance under ultraviolet (405 nm), visible (532 nm) and near-infrared (808 nm) illumination, respectively; the device has high responsivities of 160, 36, and 118 A/W, specific detectivities of 4.9 × 1011, 6.3 × 1010, and 2.1 × 1011 jones and response times of 5.5/6.8, 5.3/5.9, and 5.9/6.4 ms, respetively. This work provides a route for UV–NIR dual-mode detection and promotes the applications of these PDs in photoelectric devices for weak light and wide spectrum detection.