High-Responsivity Vis–NIR Photodetector Based on a Ag₂S/CsPbBr₃ Heterojunction

Abstract

Quantum dots (QDs) have gained significant interest in optoelectronic devices due to their excellent properties. Single-QD materials limit the high performance of photodetectors (PDs). The performance of PDs is enhanced by combining two dissimilar materials to form a heterostructure. The high responsivity vis–NIR photodetector based on a Ag2S/CsPbBr3 heterojunction is presented in this work. Using CsPbBr3 QDs as the first absorption layer and Ag2S QDs as the second absorption layer, a bipolar carrier transporting channel was built. This layered arrangement can absorb light most effectively. The formation of a heterojunction promoted charge transfer and reduced the recombination of carriers, thus improving the performance of devices. The responsivity (R) is 11.3 A/W, and the specific detectivity (D*) is 3.55 × 1010 Jones for the Ag2S/CsPbBr3 PD under 405 nm irradiation. Meanwhile, the Ag2S/CsPbBr3 heterojunction can absorb 350–1040 nm light, indicating that the device has a wide spectral detection capability (vis–NIR). The response time of the PD is 31/34 ms under 532 nm irradiation. This work provides a feasible way for high responsivity and zero-dimensional heterojunction photodetectors.