By Irene Hsiao
While the visible spectrum only comprises a narrow section of electromagnetic radiation, all matter emits heat. Detecting and visualizing heat signatures can reveal information usually imperceptible to the human eye for uses such as surveillance, scouting, astronomy, pollution monitoring, and autonomous vehicles. However, the wafer-grown bulk semiconducting materials typically used for thermal imaging have been prohibitively expensive to fabricate and process for applications outside of defense and research. Now, a pair of papers co-authored by graduate student Matthew Ackerman and postdoc Xin Tang of the Guyot-Sionnest lab demonstrate the use of inexpensive colloidal quantum dots for effective thermal detection. In "Fast and Sensitive Colloidal Quantum Dot Mid-Wave Infrared Photodetectors" (ACS Nano, 5 July 2018), they show that economical mercury telluride quantum dots can be used for thermal imaging at a speed and resolution comparable to costly crystalline materials such as mercury cadmium telluride and indium antimonide. In "Thermal Imaging with Plasmon Resonance Enhanced HgTe Colloidal Quantum Dot Photovoltaic Devices" (ACS Nano, 9 July 2018), they integrate their colloidal quantum dots with plasmonic structures to produce an improved device for midwave infrared detection.