Quantum dot (QD) passive filters present a simple and low-cost strategy for the micromation of spectrometers. In this field, the consistency between ultranarrow band gap QD fabrication and the precise control of its absorption characteristics is the key-challenge to extend QD spectrometers into the long-wave infrared (LWIR) region. Here, we show the model-based, practically precise fabrication of HgSe QDs as well as their specific spectral responses. Both the theoretical and experimental models of the HgSe QDs r–λ are formulated, which reveals the variation of transmission spectrum with the size of HgSe QDs. Then, the HgSe QDs synthesis parameter–spectral response hyperplane model and neural network model were obtained by using traditional polynomial fitting and machine learning, respectively. We also demonstrate the model-based precise fabrication of HgSe QDs with transmission characteristic peaks within 14 μm. The further simulation also shows that the 255─element QD filter array has the signal-to-noise ratio up to 14.57 dB with detection resolution about 5 cm–1.
In this work, a long-wave infrared (LWIR) quantum dot (QD) spectrometer was constructed for the first time by integrating a 255-element HgSe QD filter array with an LWIR array detector. The filter array was fabricated using a combination inkjet printing strategy with eight types of T-dodecyl mercaptan-terminated HgSe QD inks. The stability and morphology of the QDs were improved by optimizing the purification methodology and ligand modification. Combined with the compressive-sensing-based least-squares linear regression (CS-LS) algorithm, the LWIR QD spectrometer achieved a spectral resolution of 5.4 cm–1 over a wide spectral range of 8 to 14 μm, enabling the detection of the chemical warfare agent simulant dimethyl methylphosphonate. This technology is expected to facilitate the development of smaller volumes and more accurate identification of various targets in the future. This paper offers an approach to fabricating low-cost LWIR spectrometers and promoting the scale-up applications of QD devices.