Flexible infrared electronic eyes for multispectral imaging with colloidal quantum dots

Flexible infrared detectors with multispectral imaging capability are attracting great interest with increasing demand for sensitive, low-cost and scalable devices that can distinguish coincident spectral information and achieve wide field of view, low aberrations, and simple imaging optics at the same time. However, the widespread use of such detectors is still limited by the high cost of epitaxial semiconductors like HgCdTe, InSb, and InGaAs. In contrast, the solution-processability, mechanical flexibility and wide spectral tunability of colloidal quantum dots (CQDs) have inspired various inexpensive, high-performance optoelectronic devices covering important atmospheric windows from short-wave infrared (SWIR, 1.5-2.5 μm) to mid-wave infrared (MWIR 3-5 μm). Here, a potential route leading to flexible infrared electronic eyes with multispectral imaging capability is demonstrated by exploring HgTe CQDs photovoltaic detectors. At room temperature, the HgTe CQDs detectors demonstrate detectivity D∗ up to 6 × 10¹⁰ Jones in SWIR and 6.5 × 10⁸ Jones in MWIR. At cryogenic temperature, the MWIR D∗ becomes BLIP and increases to 1 × 10¹¹ Jones. Besides high D∗, the HgTe CQDs detector shows fast response with rise time below 300 ns. By stacking CQDs with different energy gaps or coupling CQDs with tunable optical filters, dual-band and multi-band infrared detection can be achieved in wide spectral ranges. Finally, infrared images are captured with flexible HgTe CQDs detectors at varying bending curvatures, showing a practical approach to sensitive infrared electronic eyes beyond the visible range.