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

Abstract

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.

Complex Optical Index of HgTe Nanocrystal Infrared Thin Films and Its Use for Short Wave Infrared Photodiode Design

“…[50] The Maxwell equations are solved in each layer and interface conditions are applied to find the final solution of the whole structure. We consider incoming plane waves under normal 2.5 µs 2019 [45] FTO/HgTe4k-ink/HgTe:6k/Au PV 560 2.5 300 0.003 3 × 10 9 260 ns 2019 [42] Al 1.4 µs 2020 [40] Au/HgTe PC 2.2 ms 2020 [46] SiO 2 /P3HT:HgTe/Au PT 2.5 300 1 10 10 1.5 µs 2020 [47] Au/LaF 3 /HgTe/Graphene PT 200 2.6 220 0.006 10 9 7 µs 2020 [48] Au/HgTe/Au (nanogap) PC 300 2.5 200 1000 2 × 10 12 25 µs 2020 [49] FTO/Al-GMR/HgTe-ink/Ag www.advopticalmat.de incidence, either with transverse magnetic (TM) or transverse electric (TE) polarizations, that is, with magnetic field or electric field parallel with the slits of the gratings, respectively. In 1D simulations, the grating is supposed to be invariant along y direction, and repeated infinitely along x direction.…”

Lithium-Ion Glass Gating of HgTe Nanocrystal Film with Designed Light-Matter Coupling

“…At such wavelengths, NCs offer an interesting alternative to epitaxially grown semiconductors to design cost-effective devices [ 3 ]. This has led to the demonstration of efficient light-emitting devices [ 4 , 5 , 6 , 7 ] as well as effective light sensors [ 8 , 9 , 10 ], including focal plane arrays used to image near- and mid-IR light [ 11 , 12 ].…”