Colloidal quantum dots (CQDs) are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared wavelengths. People may question about the upper limit on the CQD wavelength region. To date, although the CQD absorption already reaches terahertz, the practical photodetection wavelength is limited within mid-wave infrared. To figure out challenges on CQD photoresponse in longer wavelength, would reveal the ultimate property on these nanomaterials. What’s more, it motivates interest in bottom-up infrared photodetection with less than 10% cost compared with epitaxial growth semiconductor bulk. In this work, developing a re-growth method and ionic doping modification, we demonstrate photodetection up to 18 μm wavelength on HgTe CQD. At liquid nitrogen temperature, the responsivity reaches 0.3 A/W and 0.13 A/W, with specific detectivity 6.6 × 10⁸ Jones and 2.3 × 10⁹ Jones for 18 μm and 10 μm CQD photoconductors, respectively. This work is a step toward answering the general question on the CQD photodetection wavelength limitation.

胶体量子点 (CQD) 因其高通量溶液处理的可能性以及从紫外到红外波长的宽能隙可调性而受到光电器件的关注。人们可能会质疑CQD波长区域的上限。迄今为止，虽然CQD的吸收已经达到太赫兹，但实际的光电探测波长仅限于中波红外。找出较长波长下 CQD 光响应的挑战，将揭示这些纳米材料的最终特性。更重要的是，它激发了人们对自下而上红外光电检测的兴趣，与外延生长半导体体相比，其成本不到 10%。在这项工作中，我们开发了一种再生长方法和离子掺杂修饰，展示了 HgTe CQD 上高达 18 μm 波长的光电检测。在液氮温度下，响应度达到0.3 A/W和0.13 A/W，对于18 μm和10 μm CQD光电导体的比探测灵敏度分别为6.6 × 10 ⁸ Jones和2.3 × 10 ⁹ Jones。这项工作朝着回答有关 CQD 光电检测波长限制的一般问题迈出了一步。