Ultrasensitive Colloidal Quantum-Dot Upconverters for Extended Short-Wave Infrared

Abstract

Infrared-to-visible upconverters converting low-energy infrared to higher-energy visible light without bringing in complicated readout integrated circuits have triggered enormous excitement. However, existing upconverters suffer from limited sensing wavelengths, low photon-to-photon (p–p) efficiency, and high minimum detectable infrared power. Here, we reported the colloidal quantum-dot (CQD) upconverters with unprecedented performance. By using HgTe CQDs as the sensing layer, the operation spectral ranges of the upconverters are, for the first time, extended to short-wave infrared. More importantly, the resistance-area products of the HgTe CQD photodetectors are carefully optimized by interface engineering to match with the visible light-emitting diodes so that the quantum efficiency and sensitivity of upconverters can be maximized. The integrated upconverters demonstrate a high p–p efficiency of nearly 30% and a low detection limit down to 20 μW cm–2.

Band-engineered dual-band visible and short-wave infrared photodetector with metal chalcogenide colloidal quantum dots

“…S3, ESI †). 41 The dark current density of the ZnO/HgTe/Ag 2 Te devices is significantly reduced by nearly eight times (Fig. S3, ESI †).…”

Color‐Tunable Organic Light‐Emitting Displays for Interactive Multi‐Signal Visualization

“…[ 1–7 ] By integrating sensors and light‐emitting diodes (LEDs) with human‐readable output, intelligent interactive optoelectronic devices can visualize invisible signals such as optical, electrical, magnetic, chemical, and thermal to the visible displays. [ 4,5,8–15,16,17 ] Such devices not only simultaneously detect external stimuli and visualize the signal but also directly or using intermediate tools indirectly interact with users. For example, integrated photodetectors and LED devices can directly visualize external optical signals.…”

“…The emitted visible light properties can be changed according to the signal intensity, which can interact with the users through a light pen without contact. [ 2,8,9 ] Besides, wearable optoelectronic devices composed of flexible LEDs and sensors sensing temperature or electrocardiogram can be conformally integrated into human skin and real‐time continuously visualize human physiological information, which has broad applications for healthcare products, especially during the current outbreak. [ 10,17 ]…”

Mercury telluride colloidal quantum-dot focal plane array with planar p-n junctions enabled by in situ electric field–activated doping

“…In addition, the resolution of infrared imagers is improved because the pixel pitch is only determined by the readout circuit array (25). Furthermore, the bandgaps of CQDs are easily tunable and size dependent, which widely ranges from near-infrared (NIR, ~1 μm) to short-wave infrared (SWIR, 1 to 3 μm), to mid-wave infrared (MWIR, 3 to 5 μm), to even long-wave infrared (LWIR, 8 to 12 μm) (26)(27)(28).…”