This study presents a high-performance photodetector based on HgTe colloidal quantum dots (CQDs) capable of detecting infrared wavelengths up to 18 μm. The researchers developed a re-growth method and ionic doping to enhance the photodetection properties of HgTe CQDs. The photodetectors achieved a responsivity of 0.3 A/W at 18 μm and 0.13 A/W at 10 μm, with specific detectivities of 6.6 × 10⁸ Jones and 2.3 × 10⁹ Jones, respectively, at 80 K. These results demonstrate the potential of CQDs for long-wavelength infrared photodetection, which is crucial for applications in environmental monitoring, gas sensing, and hazard detection. The study also highlights the advantages of CQDs over traditional epitaxial growth methods, including lower cost and better scalability. The CQD photodetectors showed excellent stability and performance, with detectivity remaining above 2 × 10⁹ Jones after four months of exposure to air. The results indicate that proper ligand modification is essential for achieving high mobility and long carrier lifetime, which are critical for efficient photodetection. This work represents a significant step toward understanding the limitations of CQD photodetection in the infrared range.This study presents a high-performance photodetector based on HgTe colloidal quantum dots (CQDs) capable of detecting infrared wavelengths up to 18 μm. The researchers developed a re-growth method and ionic doping to enhance the photodetection properties of HgTe CQDs. The photodetectors achieved a responsivity of 0.3 A/W at 18 μm and 0.13 A/W at 10 μm, with specific detectivities of 6.6 × 10⁸ Jones and 2.3 × 10⁹ Jones, respectively, at 80 K. These results demonstrate the potential of CQDs for long-wavelength infrared photodetection, which is crucial for applications in environmental monitoring, gas sensing, and hazard detection. The study also highlights the advantages of CQDs over traditional epitaxial growth methods, including lower cost and better scalability. The CQD photodetectors showed excellent stability and performance, with detectivity remaining above 2 × 10⁹ Jones after four months of exposure to air. The results indicate that proper ligand modification is essential for achieving high mobility and long carrier lifetime, which are critical for efficient photodetection. This work represents a significant step toward understanding the limitations of CQD photodetection in the infrared range.