Colloidal quantum dot photodetectors with 10-ns response time and 80% quantum efficiency at 1,550 nm

The complex optical index of PbS nanocrystal thin films and their use for short wave infrared sensor design

“…Several reports in the literature already provide those types of diode stacks operated from 1200 to 1550 nm with impressive external quantum efficiency reaching 80%. 10,14 Further improvement requires a deep understanding of the current device performance to reveal the current bottlenecks and where future efforts must be focused. Here, we investigate the optical part of the device.…”

Suppressing the Dark Current in Quantum Dot Infrared Photodetectors by Controlling Carrier Statistics

“…[1][2][3] To date, PbS QD infrared photodetectors have been developed with various devices such as phototransistors, [4][5][6] photocon ductors, [7][8][9][10] and photodiodes (PDs). [3,[11][12][13][14][15][16][17][18] In particular, recent studies have focused on PbS quantum dot photodiode (QDPD) structures because of their high energy conversion efficiency [18][19][20] and high response speed. [11,21,22] To achieve high performance PbS QDPDs, many studies have been conducted to improve the photon-electron conversion efficiency in the devices based on n + n-p architec ture-for example, with ZnO thin films serving as the electron transport layer (ETL), halidepassivated PbS CQD (PbS halide) thin films as the active layer, and ethanedithiol (EDT)passivated PbS (PbS EDT) CQD thin films as the hole transport layer (HTL).…”

“…[3,[11][12][13][14][15][16][17][18] In particular, recent studies have focused on PbS quantum dot photodiode (QDPD) structures because of their high energy conversion efficiency [18][19][20] and high response speed. [11,21,22] To achieve high performance PbS QDPDs, many studies have been conducted to improve the photon-electron conversion efficiency in the devices based on n + n-p architec ture-for example, with ZnO thin films serving as the electron transport layer (ETL), halidepassivated PbS CQD (PbS halide) thin films as the active layer, and ethanedithiol (EDT)passivated PbS (PbS EDT) CQD thin films as the hole transport layer (HTL). Exten sive studies have been conducted to improve light absorbance by utilizing the microcavity effect of oxide/metal/oxide multi layers, [23] plasmonic effect of metal nanostructures, [24,25] and blade coating which increases the active layer thickness.…”

“…, where R is the spectral responsivity, A is the photosensitive device area, Δf is the detection bandwidth, and i noise is the noise current in the device area. [11,34] Because the noise current is mostly governed by the dark current under an applied bias, it is important to suppress the dark current.…”

Colloidal Quantum Dot Image Sensors: Technology and Marketplace Opportunities

“…Photodiodes hold promise in accessing faster response times and leveraging progress on CQD passivation toward high mobilities, and device-area miniaturization recently has led to simultaneous achievement of high external quantum efficiency in excess of 70 percent in the SWIR, high detectivity of 10 12 Jones, and response time in the order of 10 ns. 19,20 The lower dielectric constant of InAs allows for even faster response times, down to 300 ps for photodiodes with the exciton peak at 940 nm. 21 These results are a significant milestone, as they expand the use of CQD infrared photodetectors to applications demanding speeds beyond video frame rate imaging, such as industrial inspection and LiDAR.…”