Precise Control of the Oxidation State of PbS Quantum Dots Using Rapid Thermal Annealing for Infrared Photodetectors

Jin, Junyoung; Kyhm, Jihoon; Hwang, Do Kyung; Lee, Kyeong Seok; Seong, Tae Yeon; Hwang, Gyu Weon

doi:10.1021/acsanm.0c02712

Cited by 15 publications

(9 citation statements)

References 30 publications

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“…The effect of annealing on the photocurrent of devices may come from two main sources: one is the absorbance of films; the second is the oxidation degree of films. , The UV–vis spectra of PbS QDs-EDT films with different annealing temperatures are shown in Figure b. With the increase of annealing temperature, the absorbance of the device in the near-infrared region decreases to some extent, which may be due to the weakening of the quantum confinement caused by the diffusion process (necking or fusing) of nanocrystals. , In addition, annealing in air has an oxidizing effect on the PbS QDs-EDT films, especially on EDT ligands . Oxidation of EDT ligands forms a new interface between PbS and EDT which acts as a deep trap and charge extraction barrier, affecting the carrier mobility of films .…”

Section: Resultsmentioning

confidence: 99%

“…With the increase of annealing temperature, the absorbance of the device in the near-infrared region decreases to some extent, which may be due to the weakening of the quantum confinement caused by the diffusion process (necking or fusing) of nanocrystals. 36,37 In addition, annealing in air has an oxidizing effect on the PbS QDs-EDT films, especially on EDT ligands. 38 Oxidation of EDT ligands forms a new interface between PbS and EDT which acts as a deep trap and charge extraction barrier, affecting the carrier mobility of films.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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High-Performance Photodetector with a-IGZO/PbS Quantum Dots Heterojunction

et al. 2023

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Low cost, high absorption coefficient, tunable band gap, and compatibility with flexible devices make lead sulfide (PbS) quantum dots (QDs) based photoconductors promising candidates for next-generation near-infrared (NIR) photodetectors. However, the detection performance of PbS QDs-based photoconductors still needs to be further improved, because there is a trade-off among the responsivity/detectivity/bandwidth in the device development process, that is, it is difficult to improve the three parameters simultaneously. Inspired by the design idea of sensitized phototransistor, a kind of amorphous indium gallium zinc oxide (a-IGZO)/PbS QDs heterojunction photoconductor is reported in this paper. The most prominent feature of this work is that a-IGZO, like a photocurrent “amplifier”, increases the photocurrent by several orders of magnitude without generating additional noise, and thus improves the sensitivity and responsiveness of the device. Compared with the initial pure PbS QDs-based photoconductor, the heterojunction device is able to increase the photocurrent by 3000 times together with a low dark current, and improve the response speed of the device with the help of interface-assisted carrier separation and recombination. In the NIR band, the device exhibits an exciting performance with a detectivity of 1.53 × 1013 Jones, a responsivity of 19070 mA/W and a decay time of 0.39 ms, respectively. By applying the a-IGZO/PbS QDs heterojunction to paper-based devices, a flexible device with bending resistance can be obtained, and the detection performance of the device does not deteriorate after 1000 times of bending.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

High-Performance Photodetector with a-IGZO/PbS Quantum Dots Heterojunction

et al. 2023

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“…[87] Treatment with halide ligands such as cetyltrimethylammonium bromide (CTAB), tetrabutylammonium iodide (TBAI), and PbI 2 would be more effective than organic ligands. [34,[88][89][90] In 2011, Tang et al used inorganic ligands to effectively passivate the surface states of QDs for the first time to achieve high quality QD films. [34] They first introduced cadmiumtetradecyl phosphonic acid (Cd-TDPA) complex to the surface of PbS QDs, and then introduced Br − with CTAB to adhere to the surface cations (Figure 4c).…”

Section: Passivation Of Inorganic Ligandmentioning

confidence: 99%

Section: The Passivation Of Surface Defects and The Enhancements Of C...mentioning

confidence: 99%

Short‐Wave Infrared Photodetectors and Imaging Sensors Based on Lead Chalcogenide Colloidal Quantum Dots

Cai

et al. 2022

Advanced Optical Materials

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Lead chalcogenide quantum dots (QDs) are one of the next generations of ideal narrow bandgap infrared semiconductors, due to their succinct solution processing, low‐cost fabrication, size‐tunable infrared bandgap, and excellent optoelectronic properties. Tremendous efforts including synthesis methods, surface ligand engineering, and device architecture engineering, drastically contribute to the significant improvement of the performance of the photodetectors based on QDs. In recent years, with the rapid development of consumer electronics, short‐wave infrared (SWIR) imaging sensors are in urgent demand. Thanks to the flexible manipulation of the QD thin film deposition process, a variety of QD‐based imaging technologies have been studied, including single‐pixel imaging sensors, integrated imaging sensors with readout circuit, and upconversion imaging sensors, which can effectively reduce the cost of SWIR imaging sensors and promote the commercial application in the consumer electronics. Herein, recent advances of QD‐based photodetectors and imaging sensors are summarized, emphatically focusing on the synthesis of QDs, surface ligand engineering, device architecture engineering, and imaging technology.

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“…Generally, the reported annealing methods were performed on the CQD film. However, the film annealing process is not only sensitive to atmospheric conditions but may also cause necking and sintering of particles. , Most importantly, the passivating ligands are desorbed from the CQDs during the film annealing process, which leads to the formation of vacancies and defects. − Therefore, finding a controlled method to maintain the strengths and avoid the weaknesses of this annealing process remains an important but challenging task.…”

Section: Introductionmentioning

confidence: 99%

Solution Annealing Induces Surface Chemical Reconstruction for High-Efficiency PbS Quantum Dot Solar Cells

Liu

et al. 2022

ACS Appl. Mater. Interfaces

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Colloidal quantum dots (CQDs) have a large specific surface area and a complex surface structure. Their properties in diverse optoelectronic applications are largely determined by their surface chemistry. Therefore, it is essential to investigate the surface chemistry of CQDs for improving device performance. Herein, we realized an efficient surface chemistry optimization of lead sulfide (PbS) CQDs for photovoltaics by annealing the CQD solution with concentrated lead halide ligands after the conventional solution-phase ligand exchange. During the annealing process, the colloidal solution was used to transfer heat and create a secondary reaction environment, promoting the desorption of electrically insulating oleate ligands as well as the trap-related surface groups (Pb-hydroxyl and oxidized Pb species). This was accompanied by the binding of more conductive lead halide ligands on the CQD surface, eventually achieving a more complete ligand exchange. Furthermore, this strategy also minimized CQD polydispersity and decreased aggregation caused by conventional solution-phase ligand exchange, thereby contributing to yielding CQD films with twofold enhanced carrier mobility and twofold reduced trap-state density compared with those of the control. Based on these merits, the fabricated PbS CQD solar cells showed high efficiency of 11% under ambient conditions. Our strategy opens a novel and effective avenue to obtain highefficiency CQD solar cells with diverse band gaps, providing meaningful guidance for controlling ligand reactivity and realizing subtly purified CQDs.

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Precise Control of the Oxidation State of PbS Quantum Dots Using Rapid Thermal Annealing for Infrared Photodetectors

Cited by 15 publications

References 30 publications

High-Performance Photodetector with a-IGZO/PbS Quantum Dots Heterojunction

High-Performance Photodetector with a-IGZO/PbS Quantum Dots Heterojunction

Short‐Wave Infrared Photodetectors and Imaging Sensors Based on Lead Chalcogenide Colloidal Quantum Dots

Solution Annealing Induces Surface Chemical Reconstruction for High-Efficiency PbS Quantum Dot Solar Cells

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