<i>(Keynote)</i> Colloidal Quantum Dot Image Sensors with Detection Beyond 2000nm

Imaging further into the short-wave infrared region past 1700nm, and then further than 2000nm, opens up new application opportunities where distinct spectral signatures emerge, there is less solar interference, and few imaging technologies exist currently. Lead sulfide (PbS) colloidal quantum dots (CQDs) have size-dependent tunable bandgaps that extend from the near infrared to its bulk bandgap (0.41eV, ~3000nm), and are compatible with cost-efficient and readily scalable manufacturing processes. Here, we further extend the wavelength range of Emberion’s CQD image sensors, our VS20 camera, whose current sensitivity ends at 2000nm. PbS CQDs with varied bandgaps are incorporated into imagers and sensors and we find that there is a monotonic dependence of open-circuit voltage (Voc) with absorber bandgap as expected. We however notice transition points in the bandgap-Voc curve. This may relate to (i) shape changes in the quantum dot which affects surface passivation with respect to changes in crystal surface plane profiles or (ii) trap depth transitions. We also describe the temperature-dependent behaviour of devices with varied absorber bandgaps, from room temperature to cryogenic temperatures, as well, specifically looking at temperatures achievable by thermoelectric cooling in the range of -60°C to -10°C. We conclude by presenting selected application cases showcasing high-speed imaging past 2000nm including differentiation of materials, imaging under solar conditions and detection of eSWIR lasers. We also discuss prospects of maintaining performance of sub-2000nm detection in &gt;2000nm imagers and schemes for multiband detection.