Carbon Quantum Dot-Based Field-Effect Transistors and Their Ligand Length-Dependent Carrier Mobility

Kwon, Woosung; Do, Sungan; Won, Dong Chan; Rhee, Shi‐Woo

doi:10.1021/am3023898

Cited by 49 publications

(32 citation statements)

References 40 publications

(84 reference statements)

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“…The physical reason behind such high‐speed response in our photodiode is not only due to the energy alignment in our device as we have discussed above, but also due to appropriate selection of QD surface termination ligands . When we compare our device's optical response with QDs that have MPA and OA terminations, respectively, we can see that the optical response speed is twofold slower in OA‐terminated QDs (Figure S4, Supporting Information), with rising and falling times calculated as 77.6 ± 8.54 and 100 ± 14.70 ns, respectively.…”

Section: Resultsmentioning

confidence: 80%

High‐Speed Colloidal Quantum Dot Photodiodes via Accelerating Charge Separation at Metal–Oxide Interface

Jeong

Kyhm

Kyu

et al. 2019

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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,...

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Section: Resultsmentioning

confidence: 80%

High‐Speed Colloidal Quantum Dot Photodiodes via Accelerating Charge Separation at Metal–Oxide Interface

Jeong

Kyhm

Kyu

et al. 2019

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“…Except for above discussed devices, CDs or GQDs with appropriate band gap and conductivity can compensate for the disadvantages of graphene to fabricate field effect transistors (FETs). Actually, FETs have been studied by Kwon et al via solution method, effects of doping and ligand length on the performance of FETs are studied . We are expecting more researches about FETs based on CDs and GQDs for electrochemical and biological sensing.…”

Section: Discussionmentioning

confidence: 99%

Carbon and Graphene Quantum Dots for Optoelectronic and Energy Devices: A Review

Rui

Song

et al. 2015

Adv Funct Materials

1,121

666

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4929wileyonlinelibrary.com organic dyes and luminescent inorganic quantum dots. In 2010, Pan et al. successfully cut graphene sheets into blue luminescent graphene quantum dots via hydrothermal route, pushing the research of luminescent carbon materials to a climax. [ 10 ] Before that, much work has been done in the fi eld of bioimaging and optical sensing [11][12][13] while little research can be found in the optoelectronic devices or energy related applications. Since 2010, attempts on multiple applications, such as photovoltaic devices, [14][15][16][17][18] light emitting diodes, [19][20][21][22] photodetectors, [ 23,24 ] photocatalysis, [ 25 ] and lithium ion batteries, [ 26,27 ] were made. CDs and GQDs are gradually emerging in these areas and improving the performance of some kinds of devices with facile methods and low cost.Actually, GQDs can be recognized as one kind of CDs, which usually possess better crystallinity than its cousins. [ 28,29 ] In spite of the controversies on the origin of luminescence due to the excitation-dependent behavior, CDs and GQDs are expected to lead to low cost solar cells and organic LEDs (OLEDs) [ 16 ] and even can improve the performance of supercapacitors [ 27 ] and lithium ion batteries (LIBs) greatly. [ 26 ] Both of them have been synthesized with various methods, including top-down and bottom-up approaches. We are not going to talk about this because some reviews have concluded them. [30][31][32] In this Feature Article, we would like to update the latest researches about the applications of CDs and GQDs in optoelectronic devices and energy related devices, as shown in Figure 1 . Besides, there are no specifi c reviews that focus on the applications of CDs and GQDs in optoelectronic devices up to date though they have been studied for several years. In the next section, we will make a brief introduction of the microstructure and optical properties of these luminescent carbon materials. Section 3 covers the multiple applications of these interesting materials. We will focus on the application for optoelectronic and energy-related devices and make a brief introduction of other applications. In Section 4, we give a perspective for CDs and GQDs, including potential applications and possible development trend. In view of several excellent reviews focusing on different aspects of CDs and GQDs, such as their synthesis, biological applications, [ 30 ] photoluminescent properties and environmental applications, we hope this article will provide valuable insights for the current statues of CDs and GQDs research in optoelectronics and energy and stimulate new ideas and further research on their potential applications. Carbon and Graphene Quantum Dots for Optoelectronic and Energy

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“…We have also studied electronic properties of CQDs and found that trap states caused by surface defects of CQDs take part in electronic conduction . Several reports have shown the prospective electrical behavior of carbon quantum dots but still more studies are required for an adequate understanding of its’ electronic nature …”

Section: Introductionmentioning

confidence: 99%

Study of Electrical Charge Storage in Polymer‐Carbon Quantum Dot Composite

et al. 2017

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Novel carbon quantum dots (CQDs) with unexplored potential, are interesting nanomaterials for electronic investigations. Formation of surface defect sites in these Q-dots is a consequence of combinations of various carbon hybridizations. In this work nanocomposites of CQDs with an electronically inert polymer, poly vinyl alcohol (PVA), have been electrically characterized. The electronic properties were observed to be tunable by compositions of component materials. A detail conduction mechanism of charge storage within composites' layer has been worked out. The dielectric properties of composites are observed to be dependent on morphologies developed from segregation of CQDs within composites. The composites possess improved dielectric properties compared to individual component materials. Simulation of the dielectric properties reveals that the nanocomposites actually derive qualities of its' component materials.

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Carbon Quantum Dot-Based Field-Effect Transistors and Their Ligand Length-Dependent Carrier Mobility

Cited by 49 publications

References 40 publications

High‐Speed Colloidal Quantum Dot Photodiodes via Accelerating Charge Separation at Metal–Oxide Interface

High‐Speed Colloidal Quantum Dot Photodiodes via Accelerating Charge Separation at Metal–Oxide Interface

Carbon and Graphene Quantum Dots for Optoelectronic and Energy Devices: A Review

Study of Electrical Charge Storage in Polymer‐Carbon Quantum Dot Composite

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