industrial robots, or building managements. With the IoT's intrinsic nature of individual machines observing their surroundings and communicating the status with one another, [1] one of the key challenges in the field becomes the sensors. Accordingly, many different sensors such as thermal, [2] piezoelectric, [3] or strain sensors [2,4] have been researched and developed in diverse fields. Among the various sensors, we focus on high-speed optical sensor for obtaining both fast-and high-resolution imaging using colloidal quantum dots (QDs) as light sensing material.Colloidal QDs, semiconductor nanocrystals with size-dependent tunable bandgap, [5][6][7][8][9] are considered as a promising material for future device applications such as transparent [10][11][12] or flexible/stretchable opto-electronics. [13,14] For their low manufacturing cost, large-area applicability, solution processability, [8] and spectral tunability through quantum size effect, QD-based devices have achieved rapid development among a wide variety of emerging optics and electronic technologies [5,6] over the last decade.One of the efforts on developing QD-based devices has been on investigating well-performing QD-based photodiodes. [9,[15][16][17] In recent years, the understanding of the underlying physics in the operation of QD photodiodes, specifically the factors that limit their performance, has been greatly improved. [9,[15][16][17] However, it has been difficult to improve the response speed of QD-based opto-electronic detectors due to the poor transport properties of the QDs arising from geometrical and physical properties such as interparticle spacings, [5,6,9] quantum confinement effect that induces strong coupling between the photogenerated electron-hole pair to the QDs, [7,18,19] and coreshell structure of the QDs which excited charge carriers must tunnel through to the electrodes because the quantum well structure for confinement behaves as electrical intervening factor. [20][21][22] Some recent studies of QD-based opto-electronic detectors have suggested that the speed of the device can be improved by introducing the Schottky barrier between QD film and electrode layer, effectively bending the electronic bands at the interface. [9,17,[23][24][25] Oertel et al. [9] and Clifford et al. [17] demonstrated fast response of QD-based photodiodes by forming a Schottky barrier at the interface between QD film and metal contact. They demonstrated a fast response speed with electron drift by With ever-growing technological demands in the imaging sensor industry for autonomous driving and augmented reality, developing sensors that can satisfy not only image resolution but also the response speed becomes more challenging. Herein, the focus is on developing a high-speed photosensor capable of obtaining high-resolution, high-speed imaging with colloidal quantum dots (QDs) as the photosensitive material. In detail, high-speed QD photodiodes are demonstrated with rising and falling times of τ r = 28.8 ± 8.34 ns and τ f = 40 ± 9.81 ns, respectively,...
Near-infrared (NIR) photoswitching transistors have been fabricated using a hybrid structure of zinc oxide (ZnO) and quantum-dots (QDs). The ZnO active layer was prepared using a solution process, while colloidal QDs were inserted between a silicon dioxide (SiO 2 ) gate insulator and a ZnO active layer. The small band gap QDs (1.59 eV) were used to absorb low-energy NIR photons, generate photo-excited carriers, and inject them into the conduction band of the ZnO film. The device with the interfacial QDs induced photocurrents upon exposure to 780 nm-wavelength light. The photoresponsivity of the ZnO/QD device was 0.06 mA W À1 , while that of the device without QDs was 1.7 Â 10 À5 mA W À1 , which indicated that the small band gap QDs enabled a photo-induced current when exposed to NIR light. Furthermore, a photoinverter was prepared which was composed of a ZnO/QDs phototransistor and a load resistor. Photoswitching characteristics indicated that the photoinverter was well modulated by a periodic light signal of 780 nm in wavelength. The results demonstrate a useful way to fabricate NIR optoelectronics based on ZnO and QDs.Cite this: RSC Adv.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.