Ultrahigh-performance photodetectors based on low-dimensional Cs₂AgBiBr₆/CdS heterojunction

Lead-free double perovskite Cs₂AgBiBr₆ has garnered increasing attention in photoelectric applications owing to its good stability and excellent photoelectric properties. However, the poor carrier transport in Cs₂AgBiBr₆ thin films constraints their further application in photodetection. To overcome this issue, we have developed an innovative low-dimensional Cs₂AgBiBr₆/CdS heterojunction photodetector with substantially improved performance. The device achieved a high responsivity of 6.66 × 10³ A/W, an outstanding specific detectivity of 2.10 × 10¹⁴ Jones, and an impressive external quantum efficiency of 1.88 × 10⁶ %. Additionally, the on/off current ratio of the heterojunction device reached an impressive 6.18 × 10⁷. These key parameters are significantly better than those of most previously reported Cs₂AgBiBr₆-based photodetectors. Furthermore, scanning photocurrent mapping and band arrangement analysis were performed to elucidate the mechanism of photocurrent generation and transport in the low-dimensional Cs₂AgBiBr₆/CdS heterojunction photodetectors. This study highlights the outstanding performance of Cs₂AgBiBr₆/CdS heterojunction and provides a simple and effective strategy for developing high-performance Cs₂AgBiBr₆-based photodetectors.