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Chang S, Biswas P, Qin Z, Tian Z. Unusual Electrical Conductivity Enhancement in Stable n-Type Carbon Nanotube Networks. SMALL METHODS 2024:e2400585. [PMID: 39128136 DOI: 10.1002/smtd.202400585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/24/2024] [Indexed: 08/13/2024]
Abstract
Organic molecule-doped n-type single-walled carbon nanotube (SWCNT) networks are promising candidates for advanced energy applications, such as flexible thermoelectrics and photovoltaics. Yet charge transport in n-type SWCNTs is limited by two factors: i) charge localization impeding inter-tube transport caused by disordered mesostructure of randomly oriented SWCNTs and ii) reduction of charge carrier concentration driven by oxidation. Herein, studied the relationship between the mesostructure and thermoelectric properties of n-type SWCNTs obtained by surfactant-functionalization and polymer-dopant grafting. Surprisingly, the electrical conductivity of the polymer-doped SWCNTs keeps increasing with increasing polymer content, even after the saturation of carrier concentration, resulting in 12x higher conductivity on polymer-doping compared to surfactant-functionalization. While hopping transport typically dominates in disordered systems, it is shown that a bridging effect from the polymer causes unusual band-like conduction in polymer-doped SWCNTs. Additionally, since surfactants are essential to prevent oxidation and retain n-type over a long duration, shows that SWCNTs obtained through a dual-functionalization strategy using both polymer-dopant and surfactant, demonstrates a long-term stable high n-type thermoelectric power factor, when the surfactant amount is carefully controlled. Besides thermoelectrics, the findings are of general interest to developing stable and conductive n-type SWCNTs for various energy and electronic applications.
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Affiliation(s)
- Sooyon Chang
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Prithwish Biswas
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Zhao Qin
- Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - Zhiting Tian
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
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2
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Yan W, Liu A, Luo Y, Chen Z, Wu G, Chen J, Huang Q, Yang Y, Ye M, Guo W. A Highly Sensitive and Stretchable Core-Shell Fiber Sensor for Gesture Recognition and Surface Pressure Distribution Monitoring. Macromol Rapid Commun 2024; 45:e2400109. [PMID: 38594026 DOI: 10.1002/marc.202400109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 04/04/2024] [Indexed: 04/11/2024]
Abstract
This work reports a highly-strain flexible fiber sensor with a core-shell structure utilizes a unique swelling diffusion technique to infiltrate carbon nanotubes (CNTs) into the surface layer of Ecoflex fibers. Compared with traditional blended Ecoflex/CNTs fibers, this manufacturing process ensures that the sensor maintains the mechanical properties (923% strain) of the Ecoflex fiber while also improving sensitivity (gauge factor is up to 3716). By adjusting the penetration time during fabrication, the sensor can be customized for different uses. As an application demonstration, the fiber sensor is integrated into the glove to develop a wearable gesture language recognition system with high sensitivity and precision. Additionally, the authors successfully monitor the pressure distribution on the curved surface of a soccer ball by winding the fiber sensor along the ball's surface.
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Affiliation(s)
- Weizhe Yan
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
- Jiujiang Research Institute, Xiamen University, Jiujiang, 332000, P. R. China
| | - Andeng Liu
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
- Jiujiang Research Institute, Xiamen University, Jiujiang, 332000, P. R. China
| | - Yingjin Luo
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
- Jiujiang Research Institute, Xiamen University, Jiujiang, 332000, P. R. China
| | - Zhuomin Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
| | - Guoxu Wu
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
| | - Jianfeng Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
| | - Qiaoling Huang
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
- Jiujiang Research Institute, Xiamen University, Jiujiang, 332000, P. R. China
| | - Yun Yang
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
| | - Meidan Ye
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
| | - Wenxi Guo
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, 361005, P. R. China
- Jiujiang Research Institute, Xiamen University, Jiujiang, 332000, P. R. China
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3
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Balberg I. Glassy-like Transients in Semiconductor Nanomaterials. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:471. [PMID: 38470800 DOI: 10.3390/nano14050471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 02/27/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024]
Abstract
Glassy behavior is manifested by three time-dependent characteristics of a dynamic physical property. Such behaviors have been found in the electrical conductivity transients of various disordered systems, but the mechanisms that yield the glassy behavior are still under intensive debate. The focus of the present work is on the effect of the quantum confinement (QC) and the Coulomb blockade (CB) effects on the experimentally observed glassy-like behavior in semiconductor nanomaterials. Correspondingly, we studied the transient electrical currents in semiconductor systems that contain CdSe or Si nanosize crystallites, as a function of that size and the ambient temperature. In particular, in contrast to the more commonly studied post-excitation behavior in electronic glassy systems, we have also examined the current transients during the excitation. This has enabled us to show that the glassy behavior is a result of the nanosize nature of the studied systems and thus to conclude that the observed characteristics are sensitive to the above effects. Following this and the temperature dependence of the transients, we derived a more detailed macroscopic and microscopic understanding of the corresponding transport mechanisms and their glassy manifestations. We concluded that the observed electrical transients must be explained not only by the commonly suggested principle of the minimization of energy upon the approach to equilibrium, as in the mechanical (say, viscose) glass, but also by the principle of minimal energy dissipation by the electrical current which determines the percolation network of the electrical conductivity. We further suggest that the deep reason for the glassy-like behavior that is observed in the electrical transients of the nanomaterials studied is the close similarity between the localization range of electrons due to the Coulomb blockade and the caging range of the uncharged atomic-size particles in the classical mechanical glass. These considerations are expected to be useful for the understanding and planning of semiconductor nanodevices such as corresponding quantum dot memories and quantum well MOSFETs.
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Affiliation(s)
- Isaac Balberg
- The Racah Institute of Physics, The Hebrew University, Jerusalem 9190401, Israel
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4
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Khan J, Mariatti M, Zubir SA, Rusli A, Manaf AA, Khirotdin RK. Eco-friendly alkali lignin-assisted water-based graphene oxide ink and its application as a resistive temperature sensor. NANOTECHNOLOGY 2023; 35:055301. [PMID: 37879329 DOI: 10.1088/1361-6528/ad06d4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/25/2023] [Indexed: 10/27/2023]
Abstract
Inkjet-printable ink formulated with graphene oxide (GO) offers several advantages, including aqueous dispersion, low cost, and environmentally friendly production. However, water-based GO ink encounters challenges such as high surface tension, low wetting properties, and reduced ink stability over prolonged storage time. Alkali lignin, a natural surfactant, is promising in improving GO ink's stability, wettability, and printing characteristics. The concentration of surfactant additives is a key factor in fine-tuning GO ink's stability and printing properties. The current study aims to explore the detailed effects of alkali lignin concentration and optimize the overall properties of graphene oxide (GO) ink for drop-on-demand thermal inkjet printing. A meander-shaped temperature sensor electrode was printed using the optimized GO ink to demonstrate its practical applicability for commercial purposes. The sensing properties are evaluated using a simple experimental setup across a range of temperatures. The findings demonstrate a significant increase in zeta potential by 25% and maximum absorption by 84.3%, indicating enhanced stability during prolonged storage with an optimized alkali lignin concentration compared to the pure GO dispersions. The temperature sensor exhibits a remarkable thermal coefficient of resistance of 1.21 within the temperature range of 25 °C-52 °C, indicative of excellent sensitivity, response, and recovery time. These results highlight the potential of alkali lignin as a natural surfactant for improving the performance and applicability of inkjet-printable GO inks in various technological applications.
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Affiliation(s)
- Junaid Khan
- School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal Penang, 14300, Malaysia
| | - M Mariatti
- School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal Penang, 14300, Malaysia
| | - Syazana A Zubir
- School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal Penang, 14300, Malaysia
| | - Arjulizan Rusli
- School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal Penang, 14300, Malaysia
| | - Asrulnizam Abd Manaf
- Collaborative Microelectronic Design Excellence Center, Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Rd Khairilhijra Khirotdin
- Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia
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Septianto RD, Miranti R, Kikitsu T, Hikima T, Hashizume D, Matsushita N, Iwasa Y, Bisri SZ. Enabling metallic behaviour in two-dimensional superlattice of semiconductor colloidal quantum dots. Nat Commun 2023; 14:2670. [PMID: 37236922 DOI: 10.1038/s41467-023-38216-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
Semiconducting colloidal quantum dots and their assemblies exhibit superior optical properties owing to the quantum confinement effect. Thus, they are attracting tremendous interest from fundamental research to commercial applications. However, the electrical conducting properties remain detrimental predominantly due to the orientational disorder of quantum dots in the assembly. Here we report high conductivity and the consequent metallic behaviour of semiconducting colloidal quantum dots of lead sulphide. Precise facet orientation control to forming highly-ordered quasi-2-dimensional epitaxially-connected quantum dot superlattices is vital for high conductivity. The intrinsically high mobility over 10 cm2 V-1 s-1 and temperature-independent behaviour proved the high potential of semiconductor quantum dots for electrical conducting properties. Furthermore, the continuously tunable subband filling will enable quantum dot superlattices to be a future platform for emerging physical properties investigations, such as strongly correlated and topological states, as demonstrated in the moiré superlattices of twisted bilayer graphene.
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Affiliation(s)
- Ricky Dwi Septianto
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Retno Miranti
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Tomoka Kikitsu
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Takaaki Hikima
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Daisuke Hashizume
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Nobuhiro Matsushita
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Satria Zulkarnaen Bisri
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan.
- Department of Applied Physics and Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan.
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6
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Cuadra L, Salcedo-Sanz S, Nieto-Borge JC. Carrier Transport in Colloidal Quantum Dot Intermediate Band Solar Cell Materials Using Network Science. Int J Mol Sci 2023; 24:3797. [PMID: 36835214 PMCID: PMC9960920 DOI: 10.3390/ijms24043797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/05/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
Colloidal quantum dots (CQDs) have been proposed to obtain intermediate band (IB) materials. The IB solar cell can absorb sub-band-gap photons via an isolated IB within the gap, generating extra electron-hole pairs that increase the current without degrading the voltage, as has been demonstrated experimentally for real cells. In this paper, we model the electron hopping transport (HT) as a network embedded in space and energy so that a node represents the first excited electron state localized in a CQD while a link encodes the Miller-Abrahams (MA) hopping rate for the electron to hop from one node (=state) to another, forming an "electron-HT network". Similarly, we model the hole-HT system as a network so that a node encodes the first hole state localized in a CQD while a link represents the MA hopping rate for the hole to hop between nodes, leading to a "hole-HT network". The associated network Laplacian matrices allow for studying carrier dynamics in both networks. Our simulations suggest that reducing both the carrier effective mass in the ligand and the inter-dot distance increases HT efficiency. We have found a design constraint: It is necessary for the average barrier height to be larger than the energetic disorder to not degrade intra-band absorption.
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Affiliation(s)
- Lucas Cuadra
- Department of Signal Processing and Communications, University of Alcalá, 28805 Madrid, Spain
- Department of Physics and Mathematics, University of Alcalá, 28805 Madrid, Spain
| | - Sancho Salcedo-Sanz
- Department of Signal Processing and Communications, University of Alcalá, 28805 Madrid, Spain
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7
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Khan R, Rehman NU, Ilyas N, Sfina N, Barhoumi M, Khan A, Althubeiti K, Otaibi SA, Iqbal S, Rahman N, Sohail M, Ullah A, Del Rosso T, Zaman Q, Ali Khan A, Abdullaev SS, Khan A. Threshold switching in nickel-doped zinc oxide based memristor for artificial sensory applications. NANOSCALE 2023; 15:1900-1913. [PMID: 36607270 DOI: 10.1039/d2nr05257a] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Electronic devices featuring biomimetic behaviour as electronic synapses and neurons have motivated the emergence of a new era in information and humanoid robotics technologies. In the human body, a nociceptor is a unique sensory neuron receptor that is capable of detecting harmful signals, leading to the central nervous system initiating a motor response. Herein, a nickel-doped zinc oxide (NZO)/Au based memristor is fabricated for the first time and characterized for artificial nociceptor application. For this, the introduction of a nickel-doped zinc oxide (NZO) layer between P++-Si and Au electrodes is used to eliminate the surface effects of the NZO layer, resulting in improved volatile threshold switching performance. Depending on the intensity, duration, and repetition rate of the external stimuli, this newly created memristor exhibits various critical nociceptive functions, including threshold, relaxation, allodynia, and hyperalgesia. The electron trapping/detrapping to/from the traps in the NZO layer is responsible for these nociceptive properties. This kind of NZO-based device produces a multifunctional nociceptor performance that is essential for applications in artificial intelligence systems, such as neural integrated devices with nanometer-sized features.
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Affiliation(s)
- Rajwali Khan
- School of Physics and Optoelectronic Engineering, Shenzhen University, Nanshan, 518000 Shenzhen Guangdong, China.
- Department of Physics, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan.
| | - Naveed Ur Rehman
- Department of Physics, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan.
| | - Nasir Ilyas
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, P.R. China
| | - Nourreddine Sfina
- College of Sciences and Arts in Mahayel Asir, Department of Physics, King Khalid University, Abha, Saudi Arabia
- Laboratoire de la Matière Condensée et des Nanosciences (LMCN), Université de Monastir, Département de Physique, Faculté des Sciences de Monastir, Avenue de l'Environnement, 5019 Monastir, Tunisia
| | - Mohamed Barhoumi
- Laboratoire de la Matière Condensée et des Nanosciences (LMCN), Université de Monastir, Département de Physique, Faculté des Sciences de Monastir, Avenue de l'Environnement, 5019 Monastir, Tunisia
| | - Alamzeb Khan
- Department of pediatrics, Yale School of Medicine, Yale University, New Haven, CT, 0651, USA
| | - Khaled Althubeiti
- Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Sattam Al Otaibi
- Department of Electrical Engineering, Collage of Engineering, Taif University, P.O. Box11099, Taif 21944, Saudi Arabia
| | - Shahid Iqbal
- Department of Physics, Albion College, Albion, Michigan, 49224, USA
| | - Nasir Rahman
- Department of Physics, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan.
| | - Mohammad Sohail
- Department of Physics, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan.
| | - Asad Ullah
- Department of Mathematics, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan
| | - Tommaso Del Rosso
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900, Rio de janeiro, Brazil
| | - Quaid Zaman
- Department of Physic, University of Buner, Pakistan
| | - Abid Ali Khan
- Department of Chemical Sciences, University of Lakki Marwat, 28420, Lakki Marwat, KP Pakistan
| | - Sherzod Sh Abdullaev
- Independent Researcher of Andijan Machine-Building Institute, Uzbekistan/CEO of the company of "Editory" LLC, Uzbekistan
| | - Aurangzeb Khan
- Department of Physics, Abdul Wali Khan University Mardan, 23200, KP Pakistan
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8
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Xu D, Zhu X, An J, Chen G, Bao J, Xu X. UV-vis-IR Broad Spectral Photodetectors Based on VO 2-ZnO Nanocrystal Films. ACS OMEGA 2022; 7:37078-37084. [PMID: 36312338 PMCID: PMC9607667 DOI: 10.1021/acsomega.2c02549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 07/25/2022] [Indexed: 06/16/2023]
Abstract
As a narrow band semiconductor at room temperature and a metallic material above ∼68 °C, functional VO2 films are widely investigated for smart windows, whereas their potential for ultraviolet-visible-infrared (UV-vis-IR) broad spectral photodetectors has not been efficiently studied. In this report, photodetectors based on VO2-ZnO nanocrystal composite films were prepared by nanocrystal-mist (NC-mist) deposition. An enhanced photodetection switching ratio was achieved covering the ultraviolet to infrared wavelength. Due to the synergetic effect of nanosize, surface, phase transition, percolation threshold, and the band structure of the heterojunction, the transfer and transport of photogenerated carriers modulate the device performance. This study probes new chances of applying VO2-semiconductor-based nanocomposites for broad spectral photodetectors.
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9
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Kim G, Choi D, Eom SY, Song H, Jeong KS. Extended Short-Wavelength Infrared Photoluminescence and Photocurrent of Nonstoichiometric Silver Telluride Colloidal Nanocrystals. NANO LETTERS 2021; 21:8073-8079. [PMID: 34524828 DOI: 10.1021/acs.nanolett.1c02407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Demands on nontoxic nanomaterials in the short-wavelength infrared (SWIR) have rapidly grown over the past decade. Here, we present the nonstoichiometric silver chalcogenide nanocrystals of AgxTe (x > 2) and Ag2Te/Ag2S CQDs with a tunable bandgap across the SWIR region. When the atomic percent of the metal and chalcogenide elements are varied, the emission frequency of the excitonic peak is successfully extended to 2.7 μm. Surprisingly, the AgxTe CQD film responds to the SWIR light with a responsivity of 2.1 A/W at 78 K. Also, the Ag2S shell growth over the Ag2Te core enhances not only the emission intensity but also the structural rigidity, preventing crystal morphology deformation under the electron beam. The origin of the enhancement in the emission intensity and air stability of AgxTe and Ag2Te/Ag2S CQDs is carefully investigated by X-ray photoelectron spectroscopy (XPS). The optical properties and infrared photocurrent of AgxTe CQDs will provide new opportunities for solution-based SWIR applications.
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Affiliation(s)
- Gahyeon Kim
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Dongsun Choi
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - So Young Eom
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Haemin Song
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Kwang Seob Jeong
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
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10
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Nagaraja M, Geetha T, Pattar J, Mahesh HM, Prashanth S. Temperature-Dependent Studies on Electrical Properties of ZnCl2 Doped Polyaniline. POLYMER SCIENCE SERIES B 2021. [DOI: 10.1134/s1560090421050080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Zhao Q, Yang S, Ng JJ, Xu J, Choi YC, Murray CB, Kagan CR. Impurities in Nanocrystal Thin-Film Transistors Fabricated by Cation Exchange. J Phys Chem Lett 2021; 12:6514-6518. [PMID: 34240886 DOI: 10.1021/acs.jpclett.1c01551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Cation exchange is a versatile tool used to alter the composition of nanostructures and thus to design next-generation catalysts and photonic and electronic devices. However, chemical impurities inherited from the starting materials can degrade device performance. Here, we use a sequential cation-exchange process to convert PbSe into CdSe nanocrystal thin films and study their temperature-dependent electrical properties in the platform of the thin-film transistor. We show that residual Pb impurities have detrimental effects on the device turn-on, hysteresis, and electrical stability, and as the amount increases from 2% to 7%, the activation energy for carrier transport increases from 38(3) to 62(2) meV. Selection and surface functionalization of the transistor's gate oxide layer and low-temperature atomic-layer deposition encapsulation of the thin-film channel suppress these detrimental effects. By conversion of the nanocrystal thin films layer upon layer, impurities are driven away from the gate-oxide interface and mobilities improve from 3(1) to 32(3) cm2 V-1 s-1.
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12
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Gupta H, Singh J, Umapathy GR, Soni V, Ojha S, Kar S, Singh F. Signature of strong localization and crossover conduction processes in doped ZnO thin films: synergetic effect of doping fraction and dense electronic excitations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:315701. [PMID: 34132205 DOI: 10.1088/1361-648x/ac0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/17/2021] [Indexed: 06/12/2023]
Abstract
GaxZn1-xO thin films with varying Ga fraction within the solubility limit were irradiated with high-energy heavy ions to induce electronic excitations. The films show good transmittance in the visible region and a reduction of about 20% in transmittance was observed for irradiated films at higher ion fluences. The Urbach energy was estimated and showed an augmenting response upon increase in doping fraction and ion irradiation, this divulges an enhancement of localized states in the bandgap or disorder in the films. The evolution of such localized states plays a vital role in charge transport and thus the temperature dependent electrical conductivity of irradiated thin films was studied to elucidate the dominant conduction mechanisms. The detailed analysis unfolds that in the high-temperature regime (180 K <T< 300 K), the charge conduction was dominated by thermally activated band conduction followed by the nearest neighbor hopping (NNH) mechanism. Whereas in the lower temperature regime (25 K <T< 170 K), the conduction mechanism was governed by Mott-VRH (variable range hopping) followed by Efros-Shklovskii (ES)-VRH. A sudden and steep rise in resistivity below 30 K was observed for GZO films with higher doping fraction at higher ion fluence and proclaims the presence of strong localization of carriers.
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Affiliation(s)
- Himanshi Gupta
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Jitendra Singh
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - G R Umapathy
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Vijay Soni
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - S Ojha
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Soumen Kar
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Fouran Singh
- Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
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13
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Alzakia FI, Tan SC. Liquid-Exfoliated 2D Materials for Optoelectronic Applications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2003864. [PMID: 34105282 PMCID: PMC8188210 DOI: 10.1002/advs.202003864] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/19/2021] [Indexed: 05/14/2023]
Abstract
Two-dimensional (2D) materials have attracted tremendous research attention in recent days due to their extraordinary and unique properties upon exfoliation from the bulk form, which are useful for many applications such as electronics, optoelectronics, catalysis, etc. Liquid exfoliation method of 2D materials offers a facile and low-cost route to produce large quantities of mono- and few-layer 2D nanosheets in a commercially viable way. Optoelectronic devices such as photodetectors fabricated from percolating networks of liquid-exfoliated 2D materials offer advantages compared to conventional devices, including low cost, less complicated process, and higher flexibility, making them more suitable for the next generation wearable devices. This review summarizes the recent progress on metal-semiconductor-metal (MSM) photodetectors fabricated from percolating network of 2D nanosheets obtained from liquid exfoliation methods. In addition, hybrids and mixtures with other photosensitive materials, such as quantum dots, nanowires, nanorods, etc. are also discussed. First, the various methods of liquid exfoliation of 2D materials, size selection methods, and photodetection mechanisms that are responsible for light detection in networks of 2D nanosheets are briefly reviewed. At the end, some potential strategies to further improve the performance the devices are proposed.
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Affiliation(s)
- Fuad Indra Alzakia
- Department of Materials Science and EngineeringNational University of Singapore9 Engineering drive 1Singapore117574Singapore
| | - Swee Ching Tan
- Department of Materials Science and EngineeringNational University of Singapore9 Engineering drive 1Singapore117574Singapore
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14
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Unruh D, Camjayi A, Hansen C, Bobadilla J, Rozenberg MJ, Zimanyi GT. Disordered Mott-Hubbard Physics in Nanoparticle Solids: Transitions Driven by Disorder, Interactions, and Their Interplay. NANO LETTERS 2020; 20:8569-8575. [PMID: 33205978 DOI: 10.1021/acs.nanolett.0c03141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We show that adapting the knowledge developed for the disordered Mott-Hubbard model to nanoparticle (NP) solids can deliver many very helpful new insights. We developed a hierarchical nanoparticle transport simulator (HINTS), which builds from localized states to describe the disorder-localized and Mott-localized phases of NP solids and the transitions out of these localized phases. We also studied the interplay between correlations and disorder in the corresponding multiorbital Hubbard model at and away from integer filling by dynamical mean field theory. This DMFT approach is complementary to HINTS, as it builds from the metallic phase of the NP solid. The mobility scenarios produced by the two methods are strikingly similar and account for the mobilities measured in NP solids. We conclude this work by constructing the comprehensive phase diagram of PbSe NP solids on the disorder-filling plane.
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Affiliation(s)
- Davis Unruh
- Physics Department, University of California, Davis, Davis, California 95616, United States
| | - Alberto Camjayi
- Departamento de Física, FCEyN, Universidad de Buenos Aires and IFIBA, Pabellón 1, Ciudad Universitaria, 1428 CABA, Argentina
| | - Chase Hansen
- Physics Department, University of California, Davis, Davis, California 95616, United States
| | - Joel Bobadilla
- Departamento de Física, FCEyN, Universidad de Buenos Aires and IFIBA, Pabellón 1, Ciudad Universitaria, 1428 CABA, Argentina
| | - Marcelo J Rozenberg
- Laboratoire de Physique des Solides, UMR8502 CNRS - Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Gergely T Zimanyi
- Physics Department, University of California, Davis, Davis, California 95616, United States
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15
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Day R, Bediako DK, Rezaee M, Parent LR, Skorupskii G, Arguilla MQ, Hendon CH, Stassen I, Gianneschi NC, Kim P, Dincă M. Single Crystals of Electrically Conductive Two-Dimensional Metal-Organic Frameworks: Structural and Electrical Transport Properties. ACS CENTRAL SCIENCE 2019; 5:1959-1964. [PMID: 31893225 PMCID: PMC6936098 DOI: 10.1021/acscentsci.9b01006] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Indexed: 05/10/2023]
Abstract
Crystalline, electrically conductive, and intrinsically porous materials are rare. Layered two-dimensional (2D) metal-organic frameworks (MOFs) break this trend. They are porous crystals that exhibit high electrical conductivity and are novel platforms for studying fundamentals of electricity and magnetism in two dimensions. Despite demonstrated applications, electrical transport in these remains poorly understood because of a lack of single crystal studies. Here, studies of single crystals of two 2D MOFs, Ni3(HITP)2 and Cu3(HHTP)2, uncover critical insights into their structure and transport. Conductivity measurements down to 0.3 K suggest metallicity for mesoscopic single crystals of Ni3(HITP)2, which contrasts with apparent activated conductivity for polycrystalline films. Microscopy studies further reveal that these MOFs are not isostructural as previously reported. Notably, single rods exhibit conductivities up to 150 S/cm, which persist even after prolonged exposure to ambient conditions. These single crystal studies confirm that 2D MOFs hold promise as molecularly tunable platforms for fundamental science and applications where porosity and conductivity are critical.
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Affiliation(s)
- Robert
W. Day
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02138, United States
| | - D. Kwabena Bediako
- Department of Physics and John A. Paulson
School of Engineering and Applied
Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department
of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Mehdi Rezaee
- Department of Physics and John A. Paulson
School of Engineering and Applied
Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Lucas R. Parent
- Department
of Chemistry, Materials Science & Engineering, Biomedical Engineering,
International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
- Innovation
Partnership Building, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Grigorii Skorupskii
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02138, United States
| | - Maxx Q. Arguilla
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02138, United States
| | - Christopher H. Hendon
- Department
of Chemistry and Biochemistry, University
of Oregon, Eugene, Oregon 97401, United States
| | - Ivo Stassen
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02138, United States
| | - Nathan C. Gianneschi
- Department
of Chemistry, Materials Science & Engineering, Biomedical Engineering,
International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Philip Kim
- Department of Physics and John A. Paulson
School of Engineering and Applied
Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Mircea Dincă
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02138, United States
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16
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Jimenez MJM, de Oliveira RF, Bufon CCB, Pereira-da-Silva MA, Rodrigues V, Gobbi ÂL, Piazzetta MHO, Alvarez F, Cesar CL, Riul A. Enhanced mobility and controlled transparency in multilayered reduced graphene oxide quantum dots: a charge transport study. NANOTECHNOLOGY 2019; 30:275701. [PMID: 30893653 DOI: 10.1088/1361-6528/ab118e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Reduced graphene oxide (rGO) layers are known to be significantly conductive along the basal plane throughout delocalized sp2 domains. Defects present in rGO implies in disordered systems with numerous localized sites, resulting in a charge transport governed mainly by a 2D variable range hopping (VRH) mechanism. These characteristics are observed even in multilayered rGO since the through-plane conduction is expected to be insubstantial. Here, we report on the multilayer assembly of functionalized rGO quantum dots (GQDs) presenting 3D VRH transport that endows elevated charge carrier mobility, ca ∼ 236 cm2 V-1 s-1. Polyelectrolyte-wrapped GQDs were assembled by layer-by-layer technique (LbL), ensuring molecular level thickness control for the formed nanostructures, along with the adjustment of the film transparency (up to 92% in the visible region). The small size and the random distribution of GQDs in the LbL structure are believed to overcome the translational disorder in multilayered films, contributing to a 3D interlayer conduction that enhances the electronic properties. Such high-mobility, transparency-tunable films assembled by a cost-effective method possess interesting features and wide applicability in optoelectronics.
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Affiliation(s)
- Mawin J M Jimenez
- Department of Applied Physics, 'Gleb Wataghin' Institute of Physics (IFGW), University of Campinas (UNICAMP), 13083-970, Campinas, SP, Brazil
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17
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Cryer ME, Halpert JE. Room Temperature Mid-IR Detection through Localized Surface Vibrational States of SnTe Nanocrystals. ACS Sens 2018; 3:2087-2094. [PMID: 30256620 DOI: 10.1021/acssensors.8b00448] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum dots (QDs) are now well established as promising materials for room temperature mid-infrared (MIR) detection beyond 3 μm. Here, we have replaced commonly reported mercury based quantum dots with less toxic SnTe and PbSnTe. Inverse MIR detection at room temperature is demonstrated with planar, solution, and air-processed PbSnTe and SnTe QD devices. The detection mechanism is shown to be mediated by an interaction between MIR radiation and the vibrational stretches of adsorbed hydroxyl species. Devices are shown to possess mA/W responsivity via a reduction in conductance due to MIR irradiation and, unlike classic MIR photoconductors, are unaffected by visible wavelengths. As such, these devices offer the possibility of MIR thermal imaging that has an intrinsic solution to the blinding caused by higher energy light sources.
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Affiliation(s)
- Matthew E. Cryer
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Kelburn, Wellington 6012, New Zealand
| | - Jonathan E. Halpert
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Kelburn, Wellington 6012, New Zealand
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18
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Benton BT, Greenberg BL, Aydil E, Kortshagen UR, Campbell SA. Variable range hopping conduction in ZnO nanocrystal thin films. NANOTECHNOLOGY 2018; 29:415202. [PMID: 30059013 DOI: 10.1088/1361-6528/aad6ce] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Zinc oxide (ZnO) nanocrystal films are of interest for new applications in thin film transistors and as transparent conductive oxides. Previous work has concentrated on achieving highly conductive, metallic films. This work focusses on the less explored insulating to semi-insulating regime, which enables obtaining deeper insights into the roles of surface states and defect states trapped at the nanocrystal interfaces. We examine the effects of various post-deposition treatments including controlled dosing with ultraviolet light, filling the voids between nanocrystals with a matrix material deposited by atomic layer deposition, and thermal annealing of the nanocrystal films. Both Mott and Efros-Shklovskii variable range hopping are observed depending on the carrier concentration in the nanocrystals. Using the above post-treatments to transition the films between the two conduction mechanisms enables determining the Fermi level density of states and the electron localization length. To interpret our results, we propose a model based on the assumption of nanocrystals consisting of quasi-neutral cores surrounded by shells depleted by surface OH trap states. The model suggests that the primary source of the increased conductivity in ZnO nanocrystal films based on post-treatments is an increase in the ability to tunnel between nanocrystals due to a reduction of the distance between the quasi-neutral nanocrystal cores.
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Affiliation(s)
- Brian T Benton
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, United States of America
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19
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Gilmore RH, Winslow SW, Lee EMY, Ashner MN, Yager KG, Willard AP, Tisdale WA. Inverse Temperature Dependence of Charge Carrier Hopping in Quantum Dot Solids. ACS NANO 2018; 12:7741-7749. [PMID: 29927579 DOI: 10.1021/acsnano.8b01643] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In semiconductors, increasing mobility with decreasing temperature is a signature of charge carrier transport through delocalized bands. Here, we show that this behavior can also occur in nanocrystal solids due to temperature-dependent structural transformations. Using a combination of broadband infrared transient absorption spectroscopy and numerical modeling, we investigate the temperature-dependent charge transport properties of well-ordered PbS quantum dot (QD) solids. Contrary to expectations, we observe that the QD-to-QD charge tunneling rate increases with decreasing temperature, while simultaneously exhibiting thermally activated nearest-neighbor hopping behavior. Using synchrotron grazing-incidence small-angle X-ray scattering, we show that this trend is driven by a temperature-dependent reduction in nearest-neighbor separation that is quantitatively consistent with the measured tunneling rate.
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Affiliation(s)
| | | | | | | | - Kevin G Yager
- Center for Functional Nanomaterials , Brookhaven National Laboratory , Upton , New York 11973 , United States
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20
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Cryer ME, Fiedler H, Halpert JE. Photo-Electrosensitive Memristor Using Oxygen Doping in HgTe Nanocrystal Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:18927-18934. [PMID: 29722256 DOI: 10.1021/acsami.8b05429] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanocrystal-based electronic devices with multiple functionalities offer one avenue toward novel passive and active electronic components. Here, we exhibit a planar and fully air-processed thin film device that demonstrates a photoinduced memristive behavior and can be used as a transistor, photodetector, or memory device. Following long-term (60 h) air exposure, unpackaged nanocrystal films develop reliable memristive characteristics in tandem with temperature, gate, and photoresponse. The on/off values of more than 50 are achieved, and the devices show long-term stability, producing repeatable metrics over days of measurement. The on/off behavior is shown to be dependent on the previous charge flow and carrier density, implying a memristive rather than switching behavior. These observations are described within a long-term trap-filling model. This work represents an advance in the integration of nanocrystal films into electronic devices, which may lead to the development of multifunctional electronic components.
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Affiliation(s)
- Matthew E Cryer
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences , Victoria University of Wellington , P.O. Box 600, Wellington 6140 , New Zealand
| | - Holger Fiedler
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences , Victoria University of Wellington , P.O. Box 600, Wellington 6140 , New Zealand
| | - Jonathan E Halpert
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences , Victoria University of Wellington , P.O. Box 600, Wellington 6140 , New Zealand
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21
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Moon BH, Bae JJ, Joo MK, Choi H, Han GH, Lim H, Lee YH. Soft Coulomb gap and asymmetric scaling towards metal-insulator quantum criticality in multilayer MoS 2. Nat Commun 2018; 9:2052. [PMID: 29795384 PMCID: PMC5967350 DOI: 10.1038/s41467-018-04474-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 04/30/2018] [Indexed: 11/09/2022] Open
Abstract
Quantum localization–delocalization of carriers are well described by either carrier–carrier interaction or disorder. When both effects come into play, however, a comprehensive understanding is not well established mainly due to complexity and sparse experimental data. Recently developed two-dimensional layered materials are ideal in describing such mesoscopic critical phenomena as they have both strong interactions and disorder. The transport in the insulating phase is well described by the soft Coulomb gap picture, which demonstrates the contribution of both interactions and disorder. Using this picture, we demonstrate the critical power law behavior of the localization length, supporting quantum criticality. We observe asymmetric critical exponents around the metal-insulator transition through temperature scaling analysis, which originates from poor screening in insulating regime and conversely strong screening in metallic regime due to free carriers. The effect of asymmetric scaling behavior is weakened in monolayer MoS2 due to a dominating disorder. The interplay between strong interactions and presence of disorder makes atomically thin transition metal dichalcogenides an ideal platform to study phase transitions and critical phenomena. Here, the authors observe asymmetric critical exponents around the metal-insulator-transition of multilayer MoS2.
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Affiliation(s)
- Byoung Hee Moon
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea. .,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Jung Jun Bae
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Min-Kyu Joo
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Homin Choi
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea.,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Gang Hee Han
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Hanjo Lim
- Institute for Basic Science (IBS), Daejeon, 34047, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea. .,Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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22
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Hossain M, Kumar GS, Barimar Prabhava SN, Sheerin ED, McCloskey D, Acharya S, Rao KDM, Boland JJ. Transparent, Flexible Silicon Nanostructured Wire Networks with Seamless Junctions for High-Performance Photodetector Applications. ACS NANO 2018; 12:4727-4735. [PMID: 29726674 DOI: 10.1021/acsnano.8b01387] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Optically transparent photodetectors are crucial in next-generation optoelectronic applications including smart windows and transparent image sensors. Designing photodetectors with high transparency, photoresponsivity, and robust mechanical flexibility remains a significant challenge, as is managing the inevitable trade-off between high transparency and strong photoresponse. Here we report a scalable method to produce flexible crystalline Si nanostructured wire (NW) networks fabricated from silicon-on-insulator (SOI) with seamless junctions and highly responsive porous Si segments that combine to deliver exceptional performance. These networks show high transparency (∼92% at 550 nm), broadband photodetection (350 to 950 nm) with excellent responsivity (25 A/W), optical response time (0.58 ms), and mechanical flexibility (1000 cycles). Temperature-dependent photocurrent measurements indicate the presence of localized electronic states in the porous Si segments, which play a crucial role in light harvesting and photocarrier generation. The scalable low-cost approach based on SOI has the potential to deliver new classes of flexible optoelectronic devices, including next-generation photodetectors and solar cells.
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Affiliation(s)
- Mozakkar Hossain
- Technical Research Centre , Indian Association for the Cultivation of Science , Jadavpur , Kolkata - 700032 , India
| | - Gundam Sandeep Kumar
- Centre for Advanced Materials , Indian Association for the Cultivation of Science , Jadavpur , Kolkata - 700032 , India
| | - S N Barimar Prabhava
- School of Chemistry and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) , Trinity College Dublin , College Green, Dublin 2 , Ireland
| | - Emmet D Sheerin
- School of Chemistry and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) , Trinity College Dublin , College Green, Dublin 2 , Ireland
| | - David McCloskey
- School of Chemistry and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) , Trinity College Dublin , College Green, Dublin 2 , Ireland
| | - Somobrata Acharya
- Centre for Advanced Materials , Indian Association for the Cultivation of Science , Jadavpur , Kolkata - 700032 , India
| | - K D M Rao
- Technical Research Centre , Indian Association for the Cultivation of Science , Jadavpur , Kolkata - 700032 , India
| | - John J Boland
- School of Chemistry and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) , Trinity College Dublin , College Green, Dublin 2 , Ireland
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23
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Aigner W, Bienek O, Falcão BP, Ahmed SU, Wiggers H, Stutzmann M, Pereira RN. Intra- and inter-nanocrystal charge transport in nanocrystal films. NANOSCALE 2018; 10:8042-8057. [PMID: 29670986 DOI: 10.1039/c8nr00250a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The exploitation of semiconductor nanocrystal (NC) films in novel electronic and optoelectronic applications requires a better understanding of charge transport in these systems. Here, we develop a model of charge transport in NC films, based on a generalization of the concept of transport energy level ET to nanocrystal assemblies, which considers both intra- and inter-NC charge transfer processes. We conclude that the role played by each of these processes can be probed from temperature-dependent measurements of charge carrier density n and mobility μ in the same films. The model also enables the determination of the position of the Fermi energy level EF with respect to ET, an important parameter of charge transport in semiconductor materials, from the temperature dependence of n. Moreover, we provide support to an essentially temperature-independent intra-NC charge carrier mobility, considered in the transport level concept, and consequently the frequently observed temperature dependence of the overall mobility μ in NC films results from a temperature variation of the inter-NC charge transport processes. Importantly, we also conclude that the temperature dependence of conductivity in NC films should result in general from a combination of temperature variations of both n and μ. By applying the model to solution-processed Si NC films, we conclude that transport within each NC is similar to that in amorphous Si (a-Si), with charges hopping along band tail states located below the conduction band edge. For Si NCs, we obtain values of ET - EF of ∼0.25 eV. The overall mobility μ in Si NC films is significantly further reduced with respect to that typically found in a-Si due to the additional transport constraints imposed by inter-NC transfer processes inherent to a nanoparticulate film. Our model accounting for inter- and intra-NC charge transport processes provides a simple and more general description of charge transport that can be broadly applied to films of semiconductor NCs.
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Affiliation(s)
- Willi Aigner
- Walter Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany
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24
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Rastogi P, Palazon F, Prato M, Di Stasio F, Krahne R. Enhancing the Performance of CdSe/CdS Dot-in-Rod Light-Emitting Diodes via Surface Ligand Modification. ACS APPLIED MATERIALS & INTERFACES 2018; 10:5665-5672. [PMID: 29355299 DOI: 10.1021/acsami.7b18780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface ligands on colloidal nanocrystals (NCs) play an important role in the performance of NC-based optoelectronic devices such as photovoltaic cells, photodetectors, and light-emitting diodes (LEDs). On one hand, the NC emission depends critically on the passivation of the surface to minimize trap states that can provide nonradiative recombination channels. On the other hand, the electrical properties of NC films are dominated by the ligands that constitute the barriers for charge transport from one NC to its neighbor. Therefore, surface modifications via ligand exchange have been employed to improve the conductance of NC films. However, in LEDs, such surface modifications are more critical because of their possible detrimental effects on the emission properties. In this work, we study the role of surface ligand modifications on the optical and electrical properties of CdSe/CdS dot-in-rods (DiRs) in films and investigate their performance in all-solution-processed LEDs. The DiR films maintain high photoluminescence quantum yield, around 40-50%, and their electroluminescence in the LED preserves the excellent color purity of the photoluminescence. In the LEDs, the ligand exchange boosted the luminance, reaching a fourfold increase from 2200 cd/m2 for native surfactants to 8500 cd/m2 for the exchanged aminoethanethiol (AET) ligands. Moreover, the efficiency roll-off, operational stability, and shelf life are significantly improved, and the external quantum efficiency is modestly increased from 5.1 to 5.4%. We relate these improvements to the increased conductivity of the emissive layer and to the better charge balance of the electrically injected carriers. In this respect, we performed ultraviolet photoelectron spectroscopy (UPS) to obtain a deeper insight into the band alignment of the LED structure. The UPS data confirm similar flat-band offsets of the emitting layer to the electron- and hole-transport layers in the case of AET ligands, which translates to more symmetric barriers for charge injection of electrons and holes. Furthermore, the change in solubility of the NCs induced by the ligand exchange allows for a layer-by-layer deposition process of the DiR films, which yields excellent homogeneity and good thickness control and enables the fabrication of all the LED layers (except for cathode and anode) by spin-coating.
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Affiliation(s)
- Prachi Rastogi
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso 31, 16146 Genova, Italy
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25
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Qian H, Tong H, He MZ, Ji HK, Zhou LJ, Xu M, Miao XS. Observation of carrier localization in cubic crystalline Ge 2Sb 2Te 5 by field effect measurement. Sci Rep 2018; 8:486. [PMID: 29323199 PMCID: PMC5765150 DOI: 10.1038/s41598-017-18964-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/12/2017] [Indexed: 11/09/2022] Open
Abstract
The tunable disorder of vacancies upon annealing is an important character of crystalline phase-change material Ge2Sb2Te5 (GST). A variety of resistance states caused by different degrees of disorder can lead to the development of multilevel memory devices, which could bring a revolution to the memory industry by significantly increasing the storage density and inspiring the neuromorphic computing. This work focuses on the study of disorder-induced carrier localization which could result in multiple resistance levels of crystalline GST. To analyze the effect of carrier localization on multiple resistant levels, the intrinsic field effect (the change in surface conductance with an applied transverse electric field) of crystalline GST was measured, in which GST films were annealed at different temperatures. The field effect measurement is an important complement to conventional transport measurement techniques. The field effect mobility was acquired and showed temperature activation, a hallmark of carrier localization. Based on the relationship between field effect mobility and annealing temperature, we demonstrate that the annealing shifts the mobility edge towards the valence-band edge, delocalizing more carriers. The insight of carrier transport in multilevel crystalline states is of fundamental relevance for the development of multilevel phase change data storage.
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Affiliation(s)
- Hang Qian
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Tong
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China. .,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Ming-Ze He
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hong-Kai Ji
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ling-Jun Zhou
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ming Xu
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xiang-Shui Miao
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.,School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
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26
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Martinez B, Livache C, Notemgnou Mouafo LD, Goubet N, Keuleyan S, Cruguel H, Ithurria S, Aubin H, Ouerghi A, Doudin B, Lacaze E, Dubertret B, Silly MG, Lobo RPSM, Dayen JF, Lhuillier E. HgSe Self-Doped Nanocrystals as a Platform to Investigate the Effects of Vanishing Confinement. ACS APPLIED MATERIALS & INTERFACES 2017; 9:36173-36180. [PMID: 28956432 DOI: 10.1021/acsami.7b10665] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Self-doped colloidal quantum dots (CQDs) attract a strong interest for the design of a new generation of low-cost infrared (IR) optoelectronic devices because of their tunable intraband absorption feature in the mid-IR region. However, very little remains known about their electronic structure which combines confinement and an inverted band structure, complicating the design of optimized devices. We use a combination of IR spectroscopy and photoemission to determine the absolute energy levels of HgSe CQDs with various sizes and surface chemistries. We demonstrate that the filling of the CQD states ranges from 2 electrons per CQD at small sizes (<5 nm) to more than 18 electrons per CQD at large sizes (≈20 nm). HgSe CQDs are also an interesting platform to observe vanishing confinement in colloidal nanoparticles. We present lines of evidence for a semiconductor-to-metal transition at the CQD level, through temperature-dependent absorption and transport measurements. In contrast with bulk systems, the transition is the result of the vanishing confinement rather than the increase of the doping level.
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Affiliation(s)
- Bertille Martinez
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | - Clément Livache
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | | | - Nicolas Goubet
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
| | - Sean Keuleyan
- Voxtel, Inc., University of Oregon, CAMCOR, 1241 University of Oregon , Eugene, Oregon 97403, United States
| | - Hervé Cruguel
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
| | - Sandrine Ithurria
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Hervé Aubin
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N-Marcoussis , 91460 Marcoussis, France
| | - Bernard Doudin
- Université de Strasbourg, IPCMS-CNRS UMR 7504 , 23 Rue du Loess, 67034 Strasbourg, France
| | - Emmanuelle Lacaze
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
| | - Benoit Dubertret
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Mathieu G Silly
- Synchrotron-SOLEIL , Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
| | - Ricardo P S M Lobo
- LPEM, ESPCI Paris, PSL Research University , 10 rue Vauquelin, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, LPEM , 75005 Paris, France
| | - Jean-François Dayen
- Université de Strasbourg, IPCMS-CNRS UMR 7504 , 23 Rue du Loess, 67034 Strasbourg, France
| | - Emmanuel Lhuillier
- Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 4 Place Jussieu, 75005 Paris, France
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27
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Qu L, Vörös M, Zimanyi GT. Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations. Sci Rep 2017; 7:7071. [PMID: 28765599 PMCID: PMC5539282 DOI: 10.1038/s41598-017-06497-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/13/2017] [Indexed: 11/09/2022] Open
Abstract
Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator transition (MIT). To simulate MIT in NP films, we developed a hierarchical Kinetic Monte Carlo transport model. Electrons transfer between neighboring NPs via activated hopping when the NP energies differ by more than an overlap energy, but transfer by a non-activated quantum delocalization, if the NP energies are closer than the overlap energy. As the overlap energy increases, emerging percolating clusters support a metallic transport across the entire film. We simulated the evolution of the temperature-dependent electron mobility. We analyzed our data in terms of two candidate models of the MIT: (a) as a Quantum Critical Transition, signaled by an effective gap going to zero; and (b) as a Quantum Percolation Transition, where a sample-spanning metallic percolation path is formed as the fraction of the hopping bonds in the transport paths is going to zero. We found that the Quantum Percolation Transition theory provides a better description of the MIT. We also observed an anomalously low gap region next to the MIT. We discuss the relevance of our results in the light of recent experimental measurements.
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Affiliation(s)
- Luman Qu
- Physics Department, University of California, Davis, USA
| | - Márton Vörös
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
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28
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Tie M, Dhirani AA. Electrolyte-gated charge transport in molecularly linked gold nanoparticle films: The transition from a Mott insulator to an exotic metal with strong electron-electron interactions. J Chem Phys 2016; 145:104702. [DOI: 10.1063/1.4962342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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29
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Lanigan D, Thimsen E. Contact Radius and the Insulator-Metal Transition in Films Comprised of Touching Semiconductor Nanocrystals. ACS NANO 2016; 10:6744-6752. [PMID: 27398597 DOI: 10.1021/acsnano.6b02190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Nanocrystal assemblies are being explored for a number of optoelectronic applications such as transparent conductors, photovoltaic solar cells, and electrochromic windows. Majority carrier transport is important for these applications, yet it remains relatively poorly understood in films comprised of touching nanocrystals. Specifically, the underlying structural parameters expected to determine the transport mechanism have not been fully elucidated. In this report, we demonstrate experimentally that the contact radius, between touching heavily doped ZnO nanocrystals, controls the electron transport mechanism. Spherical nanocrystals are considered, which are connected by a circular area. The radius of this circular area is the contact radius. For nanocrystals that have local majority carrier concentration above the Mott transition, there is a critical contact radius. If the contact radius between nanocrystals is less than the critical value, then the transport mechanism is variable range hopping. If the contact radius is greater than the critical value, the films display behavior consistent with metallic electron transport.
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Affiliation(s)
- Deanna Lanigan
- Interface Research Group, Department of Energy, Environmental and Chemical Engineering, Washington University in Saint Louis , Saint Louis, Missouri 63130, United States
| | - Elijah Thimsen
- Interface Research Group, Department of Energy, Environmental and Chemical Engineering, Washington University in Saint Louis , Saint Louis, Missouri 63130, United States
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30
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Gao J, Zhang J, van de Lagemaat J, Johnson JC, Beard MC. Charge generation in PbS quantum dot solar cells characterized by temperature-dependent steady-state photoluminescence. ACS NANO 2014; 8:12814-12825. [PMID: 25485555 DOI: 10.1021/nn506075s] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Charge-carrier generation and transport within PbS quantum dot (QD) solar cells is investigated by measuring the temperature-dependent steady-state photoluminescence (PL) concurrently during in situ current-voltage characterization. We first compare the temperature-dependent PL quenching for PbS QD films where the PbS QDs retain their original oleate ligand to that of PbS QDs treated with 1,2-ethanedithiol (EDT), producing a conductive QD layer, either on top of glass or on a ZnO nanocrystal film. We then measure and analyze the temperature-dependent PL in a completed QD-PV architecture with the structure Al/MoO3/EDT-PbS/ZnO/ITO/glass, collecting the PL and the current simultaneously. We find that at low temperatures excitons diffuse to the ZnO interface, where PL is quenched via interfacial charge transfer. At high temperatures, excitons dissociate in the bulk of the PbS QD film via phonon-assisted tunneling to nearby QDs, and that dissociation is in competition with the intrinsic radiative and nonradiative rates of the individual QDs. The activation energy for exciton dissociation in the QD-PV devices is found to be ∼40 meV, which is considerably lower than that of the electrodeless samples, and suggests unique interactions between injected and photogenerated carriers in devices.
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Affiliation(s)
- Jianbo Gao
- Center for Advanced Solar Photophysics, National Renewable Energy Laboratory , Golden, Colorado 80401, United States
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31
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High electron mobility in thin films formed via supersonic impact deposition of nanocrystals synthesized in nonthermal plasmas. Nat Commun 2014; 5:5822. [DOI: 10.1038/ncomms6822] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 11/11/2014] [Indexed: 11/09/2022] Open
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32
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Otelaja OO, Ha DH, Ly T, Zhang H, Robinson RD. Highly conductive Cu2-xS nanoparticle films through room-temperature processing and an order of magnitude enhancement of conductivity via electrophoretic deposition. ACS APPLIED MATERIALS & INTERFACES 2014; 6:18911-18920. [PMID: 25314692 DOI: 10.1021/am504785f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A facile room-temperature method for assembling colloidal copper sulfide (Cu2-xS) nanoparticles into highly electrically conducting films is presented. Ammonium sulfide is utilized for connecting the nanoparticles via ligand removal, which transforms the as-deposited insulating films into highly conducting films. Electronic properties of the treated films are characterized with a combination of Hall effect measurements, field-effect transistor measurements, temperature-dependent conductivity measurements, and capacitance-voltage measurements, revealing their highly doped p-type semiconducting nature. The spin-cast nanoparticle films have carrier concentration of ∼ 10(19) cm(-3), Hall mobilities of ∼ 3 to 4 cm(2) V(-1) s(-1), and electrical conductivities of ∼ 5 to 6 S · cm(-1). Our films have hole mobilities that are 1-4 orders of magnitude higher than hole mobilities previously reported for heat-treated nanoparticle films of HgTe, InSb, PbS, PbTe, and PbSe. We show that electrophoretic deposition (EPD) as a method for nanoparticle film assembly leads to an order of magnitude enhancement in film conductivity (∼ 75 S · cm(-1)) over conventional spin-casting, creating copper sulfide nanoparticle films with conductivities comparable to bulk films formed through physical deposition methods. The X-ray diffraction patterns of the Cu2-xS films, with and without ligand removal, match the Djurleite phase (Cu(1.94)S) of copper sulfide and show that the nanoparticles maintain finite size after the ammonium sulfide processing. The high conductivities reported are attributed to better interparticle coupling through the ammonium sulfide treatment. This approach presents a scalable room-temperature route for fabricating highly conducting nanoparticle assemblies for large-area electronic and optoelectronic applications.
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Affiliation(s)
- Obafemi O Otelaja
- School of Electrical and Computer Engineering, Cornell University , Ithaca, New York 14853, United States
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33
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Yazdani N, Bozyigit D, Yarema O, Yarema M, Wood V. Hole Mobility in Nanocrystal Solids as a Function of Constituent Nanocrystal Size. J Phys Chem Lett 2014; 5:3522-3527. [PMID: 26278603 DOI: 10.1021/jz5015086] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Solids of semiconductor nanocrystals (NCs) are semiconductors in which the band gap can be controlled by changing the size of the constituent NCs. To date, nontrivial dependencies of the carrier mobility on the NC size have been reported. We use the time-of-flight (TOF) technique to measure the carrier mobility as a function of the NC size and find that the hole mobility of the NC solid increases dramatically with decreasing NC radius. We show that this result is in agreement with an analytic model for carrier mobility in NC solids. We further implement Monte Carlo simulations to aid in understanding the transient measurements in the context of models of dispersive transport. This work highlights that changing NC size in a device has important implications for charge transport.
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Affiliation(s)
- Nuri Yazdani
- Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Gloriastrasse 35, Zürich CH-8092, Switzerland
| | - Deniz Bozyigit
- Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Gloriastrasse 35, Zürich CH-8092, Switzerland
| | - Olesya Yarema
- Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Gloriastrasse 35, Zürich CH-8092, Switzerland
| | - Maksym Yarema
- Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Gloriastrasse 35, Zürich CH-8092, Switzerland
| | - Vanessa Wood
- Laboratory for Nanoelectronics, Department of Information Technology and Electrical Engineering, ETH Zürich, Gloriastrasse 35, Zürich CH-8092, Switzerland
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34
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Turk ME, Choi JH, Oh SJ, Fafarman AT, Diroll BT, Murray CB, Kagan CR, Kikkawa JM. Gate-induced carrier delocalization in quantum dot field effect transistors. NANO LETTERS 2014; 14:5948-5952. [PMID: 25171186 DOI: 10.1021/nl5029655] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We study gate-controlled, low-temperature resistance and magnetotransport in indium-doped CdSe quantum dot field effect transistors. We show that using the gate to accumulate electrons in the quantum dot channel increases the "localization product" (localization length times dielectric constant) describing transport at the Fermi level, as expected for Fermi level changes near a mobility edge. Our measurements suggest that the localization length increases to significantly greater than the quantum dot diameter.
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Affiliation(s)
- Michael E Turk
- Department of Physics and Astronomy, ‡Department of Electrical and Systems Engineering, §Department of Materials Science and Engineering, and ∥Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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35
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Gu H, Guo J, Yan X, Wei H, Zhang X, Liu J, Huang Y, Wei S, Guo Z. Electrical transport and magnetoresistance in advanced polyaniline nanostructures and nanocomposites. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.05.024] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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Norman ZM, Anderson NC, Owen JS. Electrical transport and grain growth in solution-cast, chloride-terminated cadmium selenide nanocrystal thin films. ACS NANO 2014; 8:7513-21. [PMID: 24960255 PMCID: PMC4216209 DOI: 10.1021/nn502829s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We report the evolution of electrical transport and grain size during the sintering of thin films spin-cast from soluble phosphine and amine-bound, chloride-terminated cadmium selenide nanocrystals. Sintering of the nanocrystals occurs in three distinct stages as the annealing temperature is increased: (1) reversible desorption of the organic ligands (≤150 °C), (2) irreversible particle fusion (200-300 °C), and (3) ripening of the grains to >5 nm domains (>200 °C). Grain growth occurs at 200 °C in films with 8 atom % Cl(-), while films with 3 atom % Cl(-) resist growth until 300 °C. Fused nanocrystalline thin films (grain size = 4.5-5.5 nm) on thermally grown silicon dioxide gate dielectrics produce field-effect transistors with electron mobilities as high as 25 cm(2)/(Vs) and on/off ratios of 10(5) with less than 0.5 V hysteresis in threshold voltage without the addition of indium.
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37
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Qin W, Liu H, Guyot-Sionnest P. Small bright charged colloidal quantum dots. ACS NANO 2014; 8:283-291. [PMID: 24350673 DOI: 10.1021/nn403893b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Using electrochemical charge injection, the fluorescence lifetimes of negatively charged core/shell CdTe/CdSe QDs are measured as a function of core size and shell thickness. It is found that the ensemble negative trion lifetimes reach a maximum (∼4.5 ns) for an intermediate shell thickness. This leads to the smallest particles (∼4.5 nm) with the brightest trion to date. Single dot measurements show that the negative charge suppresses blinking and that the trion can be as bright as the exciton at room temperature. In contrast, the biexciton lifetimes remain short and exhibit only a monotonous increase with shell thickness, showing no correlation with the negative trion decays. The suppression of the Auger process in small negatively charged CdTe/CdSe quantum dots is unprecedented and a significant departure from prior results with ultrathick CdSe/CdS core/shell or dot-in-rod structures. The proposed reason for the optimum shell thickness is that the electron-hole overlap is restricted to the CdTe core while the electron is tuned to have zero kinetic energy in the core for that optimum shell thickness. The different trend of the biexciton lifetime is not explained but tentatively attributed to shorter-lived positive trions at smaller sizes. These results improve our understanding of multiexciton recombination in colloidal quantum dots and may lead to the design of bright charged QDs for more efficient light-emitting devices.
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Affiliation(s)
- Wei Qin
- James Franck Institute, The University of Chicago , 929 East 57th Street, Chicago, Illinois 60637, United States
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38
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Chiu SC, Jhang JS, Chen JF, Fang J, Jian WB. Effects of cross-sectional area on the tunneling-junction array in octahedral PbSe colloidal-nanocrystal solids. Phys Chem Chem Phys 2013; 15:16127-31. [PMID: 23985927 DOI: 10.1039/c3cp52083h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Octahedral PbSe colloidal nanocrystals (NCs) are used to assemble a solid. Because of the special feature of the apexes of the octahedrons, the cross-sectional area of the inter-dot tunneling junctions is much smaller than that formed between spherical NCs. The inter-dot separation between NCs is easily adjusted by mild thermal treatment. Like a spherical NC-solid, the resistance of the octahedral NC-solid is exponentially dependent on the inter-dot separation. On the contrary, due to the difference in the cross-sectional area between the NCs, electron transport in the octahedral NC-solid does not follow the same model used for the explanation of electron transport in a spherical NC-solid. Through analyses of current-voltage and resistance-temperature behaviors, we have confirmed that the model of fluctuation-induced tunneling conduction fits very well with all of the data and explains the variation in the electrical properties of octahedral PbSe colloidal NC-solids after thermal annealing.
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Affiliation(s)
- Shao-Chien Chiu
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan.
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39
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Kim JY, Voznyy O, Zhitomirsky D, Sargent EH. 25th anniversary article: Colloidal quantum dot materials and devices: a quarter-century of advances. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:4986-5010. [PMID: 24002864 DOI: 10.1002/adma.201301947] [Citation(s) in RCA: 209] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Indexed: 05/22/2023]
Abstract
Colloidal quantum dot (CQD) optoelectronics offers a compelling combination of low-cost, large-area solution processing, and spectral tunability through the quantum size effect. Since early reports of size-tunable light emission from solution-synthesized CQDs over 25 years ago, tremendous progress has been made in synthesis and assembly, optical and electrical properties, materials processing, and optoelectronic applications of these materials. Here some of the major developments in this field are reviewed, touching on key milestones as well as future opportunities.
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Affiliation(s)
- Jin Young Kim
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
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40
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Chiu SC, Jhang JS, Lin YF, Hsu SY, Fang J, Jian WB. Nanocrystal shape and nanojunction effects on electron transport in nanocrystal-assembled bulks. NANOSCALE 2013; 5:8555-8559. [PMID: 23892514 DOI: 10.1039/c3nr01418e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bulk nanostructured materials are made from the assembly of octahedral PbSe nanocrystals. After thermal annealing, the artificial bulk demonstrates a large difference in behavior depending on the temperature, and a large variation of room-temperature resistivity of up to seven orders of magnitude. This variation originates from the high-indexed sharp edges of the octahedral nanocrystals. As the nanocrystals are arranged in the edge-to-edge configuration, which was observed in scanning electron microscopy images, the inter-nanocrystal capacitance is small due to the small parallel area between the nanocrystals. The small capacitance results in a high thermal fluctuation voltage and drives electron transport. The temperature-dependent resistivity and the electric field-dependent current are highly in agreement with the model of fluctuation-induced tunneling conduction. Thermal annealing reduces the inter-nanocrystal separation distance, creating a large variation in the electrical properties. Specifically, octahedral-shaped PbSe nanocrystals are employed in tailoring the electron transport in bulk nanostructured materials.
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Affiliation(s)
- Shao-Chien Chiu
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC
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41
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Kramer IJ, Sargent EH. The Architecture of Colloidal Quantum Dot Solar Cells: Materials to Devices. Chem Rev 2013; 114:863-82. [DOI: 10.1021/cr400299t] [Citation(s) in RCA: 401] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Illan J. Kramer
- Edward S. Rogers Department of Electrical & Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
| | - Edward H. Sargent
- Edward S. Rogers Department of Electrical & Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario M5S 3G4, Canada
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42
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Guyot-Sionnest P, Lhuillier E, Liu H. A mirage study of CdSe colloidal quantum dot films, Urbach tail, and surface states. J Chem Phys 2013; 137:154704. [PMID: 23083181 DOI: 10.1063/1.4758318] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Thermal deflection spectroscopy allows to measure very small absorption and uncovers absorption tails extending well below the bulk bandgap energy for CdSe quantum dots films after ligand exchange by sulfide. In this monodispersed system, the redshift, the broadening, and the absorption tails cannot be solely attributed to electronic coupling between the dots. Instead, mixing of hole states from the quantum dot and surface is proposed to dominate the changes of the interband spectra at the absorption edge.
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Affiliation(s)
- Philippe Guyot-Sionnest
- James Franck Institute, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
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43
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Qin W, Guyot-Sionnest P. Evidence for the role of holes in blinking: negative and oxidized CdSe/CdS dots. ACS NANO 2012; 6:9125-9132. [PMID: 23006012 DOI: 10.1021/nn303396c] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Thin shell CdSe/CdS colloidal quantum dots with a small 3 nm core diameter exhibit typical blinking and a binary PL intensity distribution. Electrochemical charging with one electron suppresses the blinking. With a larger core of 5 nm, the blinking statistics of on and off states is identical to that of a smaller core but the dots also display a grey state with a finite duration time (~6 ms) on glass. However, the grey state disappears on the electron-accepting ZnO nanocrystals film. In addition, the grey state PL lifetime on glass is similar to the trion lifetime measured from electrochemically charged dots. Therefore, the grey state is assigned to the photocharged negative dots. It is concluded that a grey state is always present as the dots get negatively photocharged even though it might not be observed due to the brightness of the trion and/or the duration time of the negative charge. With thick shell CdSe/CdS dots under electrochemical control, multiple charging, up to four electrons per dot, is observed as sequential changes in the photoluminescence lifetime which can be described by the Nernst equation. The small potential increment confirms the weak electron confinement with the thick CdS shell. Finally, the mechanism of hole-trapping and surface oxidation by the hole is proposed to account for the grey state and off state in the blinking.
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Affiliation(s)
- Wei Qin
- James Franck Institute, 929 E. 57th Street, The University of Chicago, Chicago, Illinois 60637, USA
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44
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Abstract
Semiconductor nanocrystals are promising materials for low-cost large-area electronic device fabrication. They can be synthesized with a wide variety of chemical compositions and size-tunable optical and electronic properties as well as dispersed in solvents for room-temperature deposition using various types of printing processes. This review addresses research progress in large-area electronic device applications using nanocrystal-based electrically active thin films, including thin-film transistors, light-emitting diodes, photovoltaics, and thermoelectrics.
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Affiliation(s)
- Matthew G. Panthani
- Department of Chemical Engineering, Texas Materials Institute, and Center for Nano and Molecular Science and Technology, University of Texas, Austin, Texas 78712
| | - Brian A. Korgel
- Department of Chemical Engineering, Texas Materials Institute, and Center for Nano and Molecular Science and Technology, University of Texas, Austin, Texas 78712
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Winhold M, Schwalb CH, Porrati F, Sachser R, Frangakis AS, Kämpken B, Terfort A, Auner N, Huth M. Binary Pt-Si nanostructures prepared by focused electron-beam-induced deposition. ACS NANO 2011; 5:9675-81. [PMID: 22050515 DOI: 10.1021/nn203134a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Binary systems of Pt-Si are prepared by electron-beam-induced deposition using the two precursors, trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPt(Me)(3)) and neopentasilane (Si(SiH(3))(4)), simultaneously. By varying the relative flux of the two precursors during deposition, we are able to study composites containing platinum and silicon in different ratios by means of energy-dispersive X-ray spectroscopy, atomic force microscopy, electrical transport measurements, and transmission electron microscopy. The results show strong evidence for the formation of a binary, metastable Pt(2)Si(3) phase, leading to a maximum in the conductivity for a Si/Pt ratio of 3:2.
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Affiliation(s)
- Marcel Winhold
- Physikalisches Institut, Goethe Universität, 60438 Frankfurt am Main, Germany
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Kang MS, Sahu A, Norris DJ, Frisbie CD. Size- and temperature-dependent charge transport in PbSe nanocrystal thin films. NANO LETTERS 2011; 11:3887-92. [PMID: 21846116 DOI: 10.1021/nl2020153] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report the size- and temperature-dependence of electron transport in thin films of PbSe nanocrystals. Upon increasing temperature over the range 28-200 K, the electron transport underwent a transition in mechanism from Efros-Shklovskii-variable-range-hopping (ES-VRH) to nearest-neighbor-hopping (NNH). The transition occurred at higher temperatures for films with smaller particles. The electron localization length, estimated from the ES-VRH model, was comparable to the nanocrystal size and scaled systematically with nanocrystal diameter. The activation energy from the NNH regime was also size-dependent, which is attributed both to size-dependent Coulomb effects and the size-distribution of nanocrystals.
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Affiliation(s)
- Moon Sung Kang
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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Wang SW, Lin HE, Lin HD, Chen KY, Tu KH, Chen CW, Chen JY, Liu CH, Liang CT, Chen YF. Transport behavior and negative magnetoresistance in chemically reduced graphene oxide nanofilms. NANOTECHNOLOGY 2011; 22:335701. [PMID: 21775805 DOI: 10.1088/0957-4484/22/33/335701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The electron transport behavior in chemically reduced graphene oxide (rGO) sheets with different thicknesses of 2, 3, and 5 nm was investigated. The four-probe method for the sheet resistance (R(S)) measurement on the intensively reduced graphene oxide samples indicates an Arrhenius characteristic of the electron transport at zero magnetic field B = 0, consistent with previous experimental results on well-reduced GO samples. The anticipated variable range hopping (VRH) transport of electrons in a two-dimensional electron system at low temperatures was not observed. The measured R(S) of the rGO samples are below 52 kΩ/square at room temperature. With the application of a magnetic field up to 4 T, negative magnetoresistance in the Mott VRH regime was observed. The magnetotransport features support a model based on the spin-coupling effect from the vacancy-induced midgap states that facilitate the Mott VRH conduction in the presence of an external magnetic field.
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Affiliation(s)
- Shu-Wei Wang
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
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