共查询到20条相似文献，搜索用时 15 毫秒
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Martin J. Sweetman Shane M. Hickey Doug A. Brooks John D. Hayball Sally E. Plush 《Advanced functional materials》2019,29(14)
Due to the favorable properties of graphene quantum dots (GQDs), there has been a rapid development of sensors, devices, and composite materials, which incorporate this 0D nanomaterial. GQDs provide a means to instill superior optical, electronic, mechanical, and adsorptive properties to various platforms and have found use as biosensors, photovoltaic devices, polymer composites, and drug delivery vehicles. One of the key factors to successfully integrating GQD technology is the intelligent choice of synthetic chemical pathways to fabricate, modify, and instill functionality in the developed platform. GQDs are decorated with a variety of functional groups that are amenable to traditional synthetic chemistry transformations; however, the technology for post‐synthetic modifications is only in its infancy. Herein, a comprehensive analysis of the chemistry available for modifying GQDs is provided; starting from methods for GQD fabrication and synthetic chemical pathways for producing functional GQDs, to the advantages, disadvantages, and challenges of specific chemistries, and finally techniques for the appropriate characterization of these functional materials. This review is meant for researchers considering entering the GQD field, as well as those more experienced, providing a practical guide on how to prepare, modify, and characterize GQDs for a broad range of applications. 相似文献
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Arundithi Ananthanarayanan Xuewan Wang Parimal Routh Barindra Sana Sierin Lim Dong‐Hwan Kim Kok‐Hwa Lim Jun Li Peng Chen 《Advanced functional materials》2014,24(20):3021-3026
Owing to their small size, biocompatibility, unique and tunable photoluminescence, and physicochemical properties, graphene quantum dots (GQDs) are an emerging class of zero‐dimensional materials promising a wide spectrum of novel applications in bio‐imaging, optical, and electrochemical sensors, energy devices, and so forth. Their widespread use, however, is largely limited by the current lack of high yield synthesis methods of high‐quality GQDs. In this contribution, a facile method to electrochemically exfoliate GQDs from three‐dimensional graphene grown by chemical vapor deposition (CVD) is reported. Furthermore, the use of such GQDs for sensitive and specific detection of ferric ions is demonstrated. 相似文献
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《Advanced functional materials》2018,28(40)
Memristors as electronic artificial synapses have attracted increasing attention in neuromorphic computing. Emulation of both “learning” and “forgetting” processes requires a bidirectional progressive adjustment of memristor conductance, which is a challenge for cutting‐edge artificial intelligence. In this work, a memristor device with a structure of Ag/Zr0.5Hf0.5O2:graphene oxide quantum dots/Ag is presented with the feature of bidirectional progressive conductance tuning. The conductance of proposed memristor is adjusted through voltage pulse number, amplitude, and width. A series of voltage pulses with an amplitude of 0.6 V and a width of 30 ns is enough to modulate conductance. The impacts of pulses with different parameters on conductance modulation are investigated, and the potential relationship between pulse amplitude and energy is revealed. Furthermore, it is proved that the pulse with low energy can realize the almost linear conductance regulation, which is beneficial to improve the accuracy of pattern recognition. The bidirectional progressive conduction modulation mimics various plastic synapses, such as spike‐timing‐dependent plasticity and paired‐pulse facilitation. This progressive conduction tuning mechanism might be attributed to the coexistence of tunneling effect and extrinsic electrochemical metallization effect. This work provides one way for memristor to attain attractive features such as bidirectional tuning, low‐power consumption, and fast speed switching that is in urgent demand for further evolution of neuromorphic chips. 相似文献
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Ling‐Ling Li Kun‐Ping Liu Guo‐Hai Yang Chun‐Ming Wang Jian‐Rong Zhang Jun‐Jie Zhu 《Advanced functional materials》2011,21(5):869-878
A novel strategy is reported for the fabrication of poly(diallyldimethylammonium chloride) (PDDA)‐protected graphene–CdSe (P‐GR‐CdSe) composites. An advanced electrogenerated chemiluminescence (ECL) immunosensor is proposed for the sensitive detection of human IgG (HIgG) by using the as‐prepared P‐GR‐CdSe composites. The P‐GR‐CdSe composite film shows high ECL intensity, good electronic conductivity, fast response, and satisfactory stability, all of which holds great promise for the fabrication of ECL biosensors with improved sensitivity. After two successive steps of amplification via the conjugation of PDDA and gold nanoparticles (GNPs) in the film, high ECL intensity is observed. The ECL immunosensor has an extremely sensitive response to HIgG in a linear range of 0.02–2000 pg mL?1 with a detection limit of 0.005 pg mL?1. The proposed sensor exhibits high specificity, good reproducibility, and long‐term stability, and may become a promising technique for protein detection. 相似文献
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Patrick Felbier Jihua Yang Jens Theis Richard William Liptak Andrew Wagner Axel Lorke Gerd Bacher Uwe Kortshagen 《Advanced functional materials》2014,24(14):1988-1993
Nonthermal plasmas allow the preparation of ligand‐free quantum dots combining high production rates with superior crystalline quality and luminescence properties. Here, ZnO quantum dots are produced in a radiofrequency capacitively‐coupled plasma, exhibiting size dependent photoluminescent quantum yields up to 60% after air exposure—the highest reported to date for any compound semiconductor quantum dots prepared in the gas phase. Systematic studies indicate the importance of the surface for the observed luminescence behavior. The high luminescent quantum yields in the visible range of the spectrum and the ligand‐free, scalable synthesis make these quantum dots good candidates for light emitting applications. 相似文献
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Bong Lee Klara Gries Alina R. Valimukhametova Ryan L. McKinney Roberto Gonzalez-Rodriguez Ugur C. Topkiran Jeffery Coffer Giridhar R. Akkaraju Anton V. Naumov 《Advanced functional materials》2023,33(48):2305506
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas9 (CRISPR associated protein 9) is a programmable gene editing tool with a promising potential for cancer gene therapy. This therapeutic function is enabled in the present study via the non-covalent delivery of CRISPR ribonucleic protein (RNP) by cationic glucosamine/PEI-derived graphene quantum dots (PEI-GQDs) that aid in overcoming physiological barriers and tracking genes of interest. PEI-GQD/RNP complex targeting the tumor protein 53 (TP53) gene mutation overexpressed in ∽50% of cancers successfully produces its double-stranded breaks in solution and in prostate cancer (PC-3) cells. Restoring this cancer “suicide” gene can promote cellular repair pathways and lead to cancer cell apoptosis. Its repair to the healthy form performed by simultaneous PEI-GQD delivery of CRISPR RNP and a gene repair template leads to a successful therapeutic outcome: 40% apoptotic cancer cell death, while having no effect on non-cancerous (HeK293) cells. The translocation of PEI-GQD/RNP complex into PC-3 cell cytoplasm is tracked via GQD intrinsic fluorescence, while enhanced green fluorescent protein (EGFP)-tagged RNP is detected in the cell nucleus, showing the successful detachment of the gene editing tool upon internalization. Using GQDs as non-viral delivery and imaging agents for CRISPR-Cas9 RNP sets the stage for image-guided cancer-specific gene therapy. 相似文献
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Xiaoming Li Muchen Rui Jizhong Song Zihan Shen Haibo Zeng 《Advanced functional materials》2015,25(31):4929-4947
As new members of carbon material family, carbon and graphene quantum dots (CDs, GQDs) have attracted tremendous attentions for their potentials for biological, optoelectronic, and energy related applications. Among these applications, bio‐imaging has been intensively studied, but optoelectronic and energy devices are rapidly rising. In this Feature Article, recent exciting progresses on CD‐ and GQD‐based optoelectronic and energy devices, such as light emitting diodes (LEDs), solar cells (SCs), photodetctors (PDs), photocatalysis, batteries, and supercapacitors are highlighted. The recent understanding on their microstructure and optical properties are briefly introduced in the first part. Some important progresses on optoelectronic and energy devices are then addressed as the main part of this Feature Article. Finally, a brief outlook is given, pointing out that CDs and GQDs could play more important roles in communication‐ and energy‐functional devices in the near future. 相似文献
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Golam Haider Prathik Roy Chia‐Wei Chiang Wei‐Chun Tan Yi‐Rou Liou Huan‐Tsung Chang Chi‐Te Liang Wei‐Heng Shih Yang‐Fang Chen 《Advanced functional materials》2016,26(4):620-628
Hybrid quantum dot–graphene photodetectors have recently attracted substantial interest because of their remarkable performance and low power consumption. However, the performance of the device greatly depends on the interfacial states and photogenerated screening field. As a consequence, the sensitivity is limited and the response time is relatively slow. In order to circumvent these challenges, herein, a composite graphene and graphene quantum dot (GQD) photodetector on lead zirconate titanate (Pb(Zr0.2Ti0.8)O3) (PZT) substrates has been designed to form an ultrasensitive photodetector over a wide range of illumination power. Under 325 nm UV light illumination, the device shows sensitivity as high as 4.06 × 109 A W?1, which is 120 times higher than reported sensitivity of the same class of devices. Plant derived GQD has a broad range of absorptivity and is an excellent candidate for harvesting photons generating electron–hole pairs. Intrinsic electric field from PZT substrate separates photogenerated electron–hole pairs as well as provides the built‐in electric field that causes the holes to transfer to the underlying graphene channel. The composite structure of graphene and GQD on PZT substrate therefore produces a simple, stable, and highly sensitive photodetector over a wide range of power with short response time, which shows a way to obtain high‐performance optoelectronic devices. 相似文献
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Kiran Lingam Ramakrishna Podila Haijun Qian Steven Serkiz Apparao M. Rao 《Advanced functional materials》2013,23(40):5062-5065
For a practical realization of graphene‐based logic devices, the opening of a band gap in graphene is crucial and has proven challenging. To this end, several synthesis techniques, including unzipping of carbon nanotubes, chemical vapor deposition, and other bottom‐up fabrication techniques have been pursued for the bulk production of graphene nanoribbons (GNRs) and graphene quantum dots (GQDs). However, only limited progress has been made towards a fundamental understanding of the origin of strong photoluminescence (PL) in GQDs. Here, it is experimentally shown that the PL is independent of the functionalization scheme of the GQDs. Following a series of annealing experiments designed to passivate the free edges, the PL in GQDs originates from edge‐states, and an edge‐passivation subsequent to synthesis quenches the PL. The results of PL studies of GNRs and carbon nano‐onions are shown to be consistent with PL being generated at the edge sites of GQDs. 相似文献
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Seungbae Ahn Wenjun Chen Miguel A. Moreno‐Gonzalez Malcolm Lockett Jiaying Wang Oscar Vazquez‐Mena 《Advanced Electronic Materials》2020,6(6)
Hybrid graphene (Gr)–quantum dot (QD) photodetectors have shown ultrahigh photoresponsivity combining the strong light absorption of QDs with the high mobility of Gr. QDs absorb light and generate photocarriers that are efficiently transported by Gr. Typically, hybrid PbS–QD/graphene photodetectors operate by transferring photogenerated holes from the QDs to Gr while photoelectrons stay in the QDs inducing a photogating mechanism that achieves a responsivity of 6 × 107 A W−1. However, despite such high gain, these systems have poor charge collection with quantum efficiency below 25%. Herein, a ZnO intermediate layer (PbS‐QD/ZnO/Gr) is introduced to improve charge collection by forming an effective p‐n PbS‐ZnO junction driving the electrons to the ZnO layer and then to Gr. This improves the photoresponsivity of the devices by nearly an order of magnitude with respect to devices without ZnO. Charge transfer to Gr is demonstrated by monitoring the change in Fermi level under illumination for conventional PbS‐QD/Gr and for ZnO intermediate PbS‐QD/ZnO/Gr devices. These results improve the capabilities of hybrid QD/Gr configurations for optoelectronic devices. 相似文献
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Ling‐Ling Li Jing Ji Rong Fei Chong‐Zhi Wang Qian Lu Jian‐Rong Zhang Li‐Ping Jiang Jun‐Jie Zhu 《Advanced functional materials》2012,22(14):2971-2979
With the assistance of microwave irradiation, greenish‐yellow luminescent graphene quantum dots (gGQDs) with a quantum yield (QY) up to 11.7% are successfully prepared via cleaving graphene oxide (GO) under acid conditions. The cleaving and reduction processes are accomplished simultaneously using microwave treatment without additional reducing agent. When the gGQDs are further reduced with NaBH4, bright blue luminescent graphene quantum dots (bGQDs) are obtained with a QY as high as 22.9%. Both GQDs show well‐known excitation‐dependent PL behavior, which could be ascribed to the transition from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) with a carbene‐like triplet ground state. Electrochemiluminescence (ECL) is observed from the graphene quantum dots for the first time, suggesting promising applications in ECL biosensing and imaging. The ECL mechanism is investigated in detail. Furthermore, a novel sensor for Cd2+ is proposed based on Cd2+ induced ECL quenching with cysteine (Cys) as the masking agent. 相似文献
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Aleksandr P. Litvin Xiaoyu Zhang Elena V. Ushakova Andrey L. Rogach 《Advanced functional materials》2021,31(18):2010768
Metal halide perovskite-based optoelectronics has experienced an unprecedented development in the last decade, while further improvements of efficiency, stability, and economic gains of such devices require novel engineering concepts. The use of carbon nanoparticles as versatile auxiliary components of perovskite-based optoelectronic devices is one strategy that offers several advantages in this respect. In this review, first, a brief introduction is offered on metal halide perovskites and on the major performance characteristics of related optoelectronic devices. Then, the versatility and merits of different kinds of carbon nanoparticles, such as graphene quantum dots and carbon dots, are discussed. The tunability of their electronic properties is focused upon, their interactions with perovskite components are analyzed, and different strategies of their implementation in optoelectronic devices are introduced, which include solar cells, light-emitting diodes, luminescent solar concentrators, and photodetectors. It is shown how carbon nanoparticles influence charge carriers extraction and transport, promote perovskite crystallization, allow for efficient passivation, block ion migration, suppress hysteresis, enhance their environmental stability, and thus improve the performance of perovskite-based optoelectronic devices. 相似文献
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Liangfeng Chen Siwei Yang Yongqiang Li Zheng Liu Hang Wang Yuqing Zhang Kai Qi Gang Wang Peng He Guqiao Ding 《Advanced functional materials》2024,34(36):2401246
Although various effective machine-learning attempts have been made to investigate the photoluminescence properties of graphene quantum dots (GQDs) or carbon dots, the physical correlation behind their mathematical models has not been reasonably elucidated. In this work, the correlation mechanism between the precursor structure and quantum yield of GQDs prepared by a “bottom-up” method is sufficiently studied. Three decisive factors affecting the quantum yield of GQDs during the two-component reaction system preparation are revealed, namely structure factor (F1), temperature factor (F2), and concentration factor (F3). The symmetry of precursors in the formation of sp2–sp3 hybrid carbon nanostructures is considered the key factor in the modulation of fluorescence quantum yield in GQDs. Notably, in contrast to previous work, it is first demonstrated that the normal modes of molecular vibration are the core mechanism by which the structural properties of the precursors act on the fluorescence quantum yield of GQDs. The conclusion further proved conducive in obtaining GQDs with a higher absolute quantum yield up to 83.33%. 相似文献
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Zhi-Wen Gao Yong Wang Hui Liu Jiayun Sun Jinwook Kim Yan Li Baomin Xu Wallace C. H. Choy 《Advanced functional materials》2021,31(27):2101438
Organic–inorganic hybrid perovskites have reached an unprecedented high efficiency in photovoltaic applications, which makes the commercialization of perovskite solar cells (PSCs) possible. In the past several years, particular attention has been paid to the stability of PSC devices, which is a critical issue for becoming a practical photovoltaic technology. In particular, the interface-induced degradation of perovskites should be the dominant factor causing poor stability. Here, imidazole bromide functionalized graphene quantum dots (I-GQDs) are demonstrated to regulate the interface between the electron transport layer (ETL) and formamidinium lead iodide (FAPbI3) perovskite layer. The incorporation of I-GQDs not only reduces the interface defects for achieving a better energy level alignment between ETL and perovskite, but also improves the film quality of FAPbI3 perovskite including enlarged grain size, lower trap density, and a longer carrier lifetime. Consequently, the planar FAPbI3 PSCs with I-GQDs regulation achieve a high efficiency of 22.37% with enhanced long-term stability. 相似文献
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Cameron Jennings Xiangyu Ma Thushan Wickramasinghe Matthew Doty Michael Scheibner Eric Stinaff Morgan Ware 《Advanced Quantum Technologies》2020,3(2)
Coupled quantum dots (CQDs) that consist of two InAs QDs stacked along the growth direction and separated by a relatively thin tunnel barrier have been the focus of extensive research efforts. The expansion of available states enabled by the formation of delocalized molecular wavefunctions in these systems has led to significant enhancement of the already substantial capabilities of single QD systems and have proven to be a fertile platform for studying light–matter interactions, from semi‐classical to purely quantum phenomena. Observations unique to CQDs, including tunable g‐factors and radiative lifetimes, in situ control of exchange interactions, coherent phonon effects, manipulation of multiple spins, and nondestructive spin readout, along with possibilities such as quantum‐to‐quantum transduction with error correction and multipartite entanglement, open new and exciting opportunities for CQD‐based photonic quantum technologies. This review is focused on recent CQD work, highlighting aspects where CQDs provide a unique advantage and with an emphasis on results relevant to photonic quantum technologies. 相似文献
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Minsu Park Yangho Jeong Hyung Suk Kim Woochan Lee Sang-Hyeon Nam Sukki Lee Hyewon Yoon Jin Kim Seunghyup Yoo Seokwoo Jeon 《Advanced functional materials》2021,31(29):2102741
Graphene quantum dots (GQDs) have attracted great attention as next-generation luminescent nanomaterials due to the advantages of a low-cost process, low toxicity, and unique photoluminescence (PL). However, in the solid-state, the strong π−π stacking interactions between the basal planes of GQDs lead to aggregation-caused PL quenching (ACQ), which impedes practical application to light-emitting devices. Here, surface functionalized GQDs (F-GQDs) by polyhedral oligomeric silsesquioxane (POSS), poly(ethylene glycol) (PEG), and hexadecylamine (HDA) to reduce π−π stacking-induced ACQ is presented. The POSS-, PEG-, and HDA-functionalized GQDs show a significant enhancement in PL intensity compared to bare GQDs by 9.5-, 9.0-, and 5.6-fold in spin-coated film form and by 8.3-, 7.2-, and 3.4-fold in drop-casted film form, respectively. Experimental results and molecular dynamics simulations indicate that steric hindrance of the functionalization agent contributes to reducing the π−π stacking between adjacent GQDs and thereby enabling quenching-resistant PL in the solid-state. Moreover, the GQD-based white light-emitting diodes fabricated by mounting HDA-GQDs on a UV-LED chip exhibits efficient down-conversion for white light emission with a high color rendering index of 86.2 and a correlated-color temperature of 5612 K at Commission Internationale de l'Éclairage coordinates of (0.333, 0.359). 相似文献