## 4 Conclusions  
In summary, we successfully synthesized 2D layered Bi\({}_{2}\)O\({}_{2}\)Se samples using low-pressure chemical vapor deposition and demonstrated a broadband and high-performance infrared photodetector based on the hybrid structure of high-mobility 2D Bi\({}_{2}\)O\({}_{2}\)Se and PbS QDs. The fast photoresponse (rise/fall time) of the hybrid photodetector reached 0.15/0.651 s (compared to 0.63/1.27 s for bare Bi\({}_{2}\)O\({}_{2}\)Se), attributed to the rapid photogenerated carrier separation at the formed type-II interface. Compared to few-layer Bi\({}_{2}\)O\({}_{2}\)Se photodetectors, the hybrid photodetector expanded its photoresponse range to near 1350 nm. The responsivity (R) of the hybrid photodetector within 1000 nm was nearly 20 times higher than that of few-layer Bi\({}_{2}\)O\({}_{2}\)Se (reaching 14.89 A/W at 450 nm). The construction of the PbS quantum dots and Bi\({}_{2}\)O\({}_{2}\)Se heterojunction further validates the feasibility of the theoretical approach of combining photosensitive materials with channel materials. By utilizing the high light response of the photosensitive material, incident photons are efficiently converted into photogenerated electrons, and the high-speed charge transfer of the channel material allows photogenerated carriers to cycle multiple times within their lifetime, achieving high gain. This device structure holds broad prospects for future applications in the field of photodetection, offering wide spectral response range, high responsivity, miniaturization, and portability. To further enhance the optoelectronic performance of the hybrid heterojunction, future research should focus on the intrinsic properties of 2D materials and the surface defects of QDs. Improving the preparation and surface treatment processes of QDs and 2D materials will broaden the spectral response range and enhance the device's performance.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14135914/s1](https://www.mdpi.com/article/10.3390/app14135914/s1)]([https://www.mdpi.com/article/10.3390/app14135914/s1](https://www.mdpi.com/article/10.3390/app14135914/s1)), Figure S1. OM images of Bi\({}_{2}\)O\({}_{2}\)Se growth at different substrate temperatures. Figure S2. I-V curves of the bare Bi\({}_{2}\)O\({}_{2}\)Se under different wavelengths. Figure S3. Bare Bi\({}_{2}\)O\({}_{2}\)Se device and its optoelectronic detection performance. Figure S4. Optoelectronic performance of the bare PbS device.  
Conceptualization, B.Z.; material preparation, B.Z.; data curation, B.Z. and W.L.; writing--original draft preparation, B.Z.; writing--review and editing, Z.W., Y.X. and Y.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Natural Science Foundation of China (No. 12204198).  
Not applicable.  
Figure 5: Schematic of the mechanism for the PbS QDs/Bi\({}_{2}\)O\({}_{2}\)Se hybrid photodetector. (**a**) Photogenerated carrier flow diagram of the hybrid photodetector at V\({}_{\text{ds}}\) = 1 V. (**b**) Diagram of non-radiative energy transfer in PbS QDs and defect capture of carriers in Bi\({}_{2}\)O\({}_{2}\)Se.  
Data Availability Statement: The original contributions presented in the study are included in the article and Supplementary Materials, further inquiries can be directed to the corresponding authors.  
The authors declare no conflicts of interest.