Large Photogain in Multicolor Nanocrystal Photodetector Arrays Enabling Room-Temperature Detection of Targets above 100 °c

Colloidal nanocrystals (NCs) are often described as solution processable semiconductors. However, many state of the art devices use them in the same manner as bulk semiconductors by fabricating conventional device structures using vacuum deposition techniques. Here we show that colloidal NCs can be deployed in an array of planar photodetectors produced using a simple method of patterned spray coating to achieve room-temperature detection of targets at 100 °C. HgTe nanocrystals are synthesized with varying band gaps to produce arrays of multicolor detectors operating in the mid-infrared (MIR). We demonstrate a 15-pixel active imaging system that consists of a polymer substrate and up to four 4-color pixels. The performance of these devices at room temperature is enhanced by a low intensity photogain effect at 5 V bias that permits a maximum EQE of 1900 ± 300% for a pixel with a 3.3 μm bandgap. This device permits detection of an object only 75 °C warmer than the detector in a noisy environment, acting as a proof of concept for room-temperature NC devices that are able to image objects at around 100 °C. We further show that the gain is sensitive to the total incident flux and the device bias, suggesting a trap-assisted mechanism. Finally, it is shown that solution patterned NC fabrication methods can deliver adequate reproducibility between pixels to enable production of an imaging plane of multiple pixels with a 15-pixel device and deliver some degree of spatial resolution.