Extending Polarization Detection to the Infrared Region via Sb₂Se₃ Nanowires/PbS Quantum Dots Heterojunctions

Polarization-sensitive infrared photodetectors find broad use in military and industrial fields and thus have emerged as a research hotspot in recent years. Owing to the intrinsic asymmetric structure, Sb₂Se₃ nanowires hold significant application in polarization detection. However, constrained by bandgap width, their polarization detection wavelength is limited to below 1000 nm. In this work, Sb₂Se₃ nanowires (NWs)/PbS quantum dots (QDs) heterojunctions were fabricated, with the carrier transport efficiency at the heterojunction interface enhanced via long-to-short-chain ligand exchange. Compared with pure Sb₂Se₃ NW-based photodetectors (PDs), the Sb₂Se₃ NWs/PbS QDs heterojunction-based counterparts not only have their detection wavelength extended to 1.55 μm but, more notably, their polarization detection wavelength is also extended to 1.55 μm. The photodetector exhibits responsivities (R_λ) of 1.12 A/W and 0.86 A/W for 1.31 and 1.55 μm incident lasers, with measured dichroic ratios of 1.38 and 1.58, respectively, for the polarized light at these two wavelengths. The ultraviolet photoelectron spectroscopy (UPS) analysis reveals that the separation of photogenerated carriers at the heterojunction interface enhances the absorption of infrared polarized light by the defect energy levels in Sb₂Se₃ NWs, thereby extending the polarized photoresponse wavelength of the heterojunction to 1.55 μm. Moreover, by employing convolution kernels constructed from the infrared polarization R_λ of the Sb₂Se₃/PbS heterojunction-based PD, the artificial neural network (ANN) can effectively extract feature information, reduce redundant data and noise, and facilitate image recognition. These outstanding polarization detection performances demonstrate that extending the polarization detection wavelength to the infrared region via QDs coupling is an innovative and reliable approach with promising prospects for further applications.