41 research outputs found
High Responsivity and Response Speed Single‐Layer Mixed‐Cation Lead Mixed‐Halide Perovskite Photodetectors Based on Nanogap Electrodes Manufactured on Large‐Area Rigid and Flexible Substrates
No full textAdv. Funct. Mater. 2019, 29, 1901371 In the initially published version of this article, the name of Akmaral Seitkhan was omitted from the final authors list. The correct author list is as follows: Dimitra G. Georgiadou,* Yen-Hung Lin, Jongchul Lim, Sinclair Ratnasingham, Akmaral Seitkhan, Martyn A. McLachlan, Henry J. Snaith, and Thomas D. Anthopoulos* The respective updated author affiliations are as follows: Dr. D. G. Georgiadou, Prof. T. D. Anthopoulos Department of Physics and Centre for Plastic Electronics Blackett Laboratory Imperial College London Exhibition Road, London SW7 2BW, UK E-mail: [email protected]; [email protected] Dr. D. G. Georgiadou, S. Ratnasingham, Dr. M. A. McLachlan Department of Materials and Centre for Plastic Electronics Imperial College London Prince Consort Road, London SW7 2BP, UK Dr. Y.-H. Lin, Dr. J. Lim, Prof. H. J. Snaith Department of Physics University of Oxford Clarendon Laboratory Parks Road, Oxford OX1 3PU, UK A. Seitkhan, Prof. T. D. Anthopoulos Division of Physical Sciences and Engineering King Abdullah University of Science and Technology (KAUST) Thuwal 23955–6900, Saudi Arabia The authors apologize for any inconvenience this error may have caused.</p
High responsivity and response speed single-layer mixed-cation lead mixed-halide perovskite photodetectors based on nanogap electrodes manufactured on large-area rigid and flexible substrates
No full textMixed-cation lead mixed-halide perovskites are employed as the photoactive material in single-layer solution-processed photodetectors fabricated with coplanar asymmetric nanogap Al–Au and indium tin oxide–Al electrodes. The nanogap electrodes, bearing an interelectrode distance of ≈10 nm, are patterned via adhesion lithography, a simple, low-cost, and high-throughput technique. Different electrode shapes and sizes are demonstrated on glass and flexible plastic substrates, effectively engineering the device architecture, and, along with perovskite film and material optimization, paving the way toward devices with tunable operational characteristics. The optimized coplanar nanogap junction perovskite photodetectors show responsivities up to 33 A W−1, specific detectivity on the order of 1011 Jones, and response times below 260 ns, while retaining a low dark current (0.3 nA) under −2 V reverse bias. These values outperform the vast majority of perovskite photodetectors reported so far, while avoiding the complicated fabrication steps involved in conventional multilayer device structures. This work highlights the promising potential of the proposed asymmetric nanogap electrode architecture for application in the field of flexible optoelectronics.</p
Aerosol processing of halide perovskites
No full textOrgano-metal halide perovskites (OMHPs) research has progressed rapidly, with photovoltaic (PV) devices reaching over 20% efficiency. However, scalable production of these devices is an ongoing challenge. This study demonstrated the ability to grow halide perovskite films via aerosol assisted chemical vapour deposition (AACVD). AACVD is a scalable deposition process and one advantage of this method compared to conventional CVD is the fact that the precursors do not need to be vapourised. This allows for lower operating temperature, less complex equipment, and therefore lower overall cost.
In this thesis, Methylammonium lead-triiodide (MAPI) films were deposited by sequentially passing aerosolized precursor solvent solutions into a reactor containing a heated substrate. In this study two different precursor systems were utilized, one based on lead iodide and the other on lead acetate. The first produced thick films, which were characterized extensively using X-ray diffraction, UV-visible spectroscopy, Kelvin probe measurements, ambient photoemission spectroscopy, time of flight measurements and Hall effect measurements. The second system allowed for the deposition of thinner films, more suitable for photovoltaic applications. These films were again extensively characterised but also allowed for the fabrication of the first working OMHP device utilising AACVD.
Furthermore, this study demonstrated an ability to use aerosols as a scalable post-deposition treatment on existing films, modulating the morphology and boosting the performance of conventionally spin-coated films to over 20% PCE. Treatment of films was accomplished by exposing spin-coated films to aerosolised solvents. Using these treatments, it is shown that the morphology of the films can be drastically and controllably improved. This study also reveals improvements in charge carrier lifetimes and a general improvement in most (PV) parameters. This has further led to experimentation with HTL-free devices and thick OMHP layers, with both showing significant improvements after the aerosol treatment.Open Acces
Hybrid Solar Cells
No full textThe field of hybrid solar cells promises a combination of the economic and easy production of organic molecules, with the stability and performance of inorganic materials. One of the pioneering developments in this field was the creation of the dye-sensitized solar cell in 1991. A number of different organic and inorganic material combinations have since been researched. Device architecture has also been extensively explored, with many variations in how the organic and inorganic layers are arranged and deposited. Inorganic layers have attracted much attention. Likewise, research into electrolytes has shown great advances, with some of the latest research showing positive results with solid state electrolytes. The sensitizer or dye has also been an area of intense research. To date, many different organic dye families have been explored in an effort to improve efficiency. Methylammonium lead triiodide perovskite is one of the more recent dyes and showed an incredible increase in efficiency. This ushered in a new field of research based on perovskite-type sensitizers. There is currently a drive to produce more stable and higher performing perovskites. Variations in composition and stoichiometry have so far yielded a large number of improvements, but stability is still a major concern. Both of these hybrid cell technologies are very promising. However, this field is still immature, with much development still required to improve stability and processing.</jats:p
Australian Sphingidae – DNA Barcodes Challenge Current Species Boundaries and Distributions
No full text© 2014 Rougerie et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
Low Temperature Scalable Deposition of Copper(I) Thiocyanate Films via Aerosol-Assisted Chemical Vapor Deposition
No full textCopper(I) thiocyanate (CuSCN) is a stable, wide bandgap (>3.5 eV), low-cost p-type semiconductor widely used in a variety of optoelectronic applications, including thin film transistors, organic light-emitting diodes, and photovoltaic cells. For CuSCN to have impact in the commercial fabrication of such devices, large-area, low-cost deposition techniques are required. Here, we report a novel technique for deposition of CuSCN that addresses these challenges. Aerosol-assisted chemical vapor deposition (AACVD) is used to deposit highly crystalline CuSCN films at low temperature. AACVD is a commercially viable technique due to its low cost and inherent scalability. In this study, the deposition temperature, CuSCN concentration and carrier gas flow rate were studied and optimized, resulting in homogeneous films grown over areas approaching 30 cm2. At the optimized values, i.e., 60 °C using a 35 mg/mL solution and a carrier gas flow rate of 0.5 dm3/min, the film growth rate is around 100 nm/min. We present a thorough analysis of the film growth parameters and the subsequent morphology, composition, and structural and optical properties of the deposited thin films
Modeling the effects of trait-mediated dispersal on coexistence of mutualists
No full text© 2020 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) Even though mutualistic interactions are ubiquitous in nature, we are still far from making good predictions about the fate of mutualistic communities under threats such as habitat fragmentation and climate change. Fragmentation often causes declines in abundance of a species due to increased susceptibility to edge effects between remnant habitat patches and lower quality “matrix” surrounding these focal patches. It has been argued that ecological communities are replete with trait-mediated indirect effects, and that these effects may sometimes contribute more to the dynamics of a population than direct density-mediated effects, e.g., lowering an organism\u27s fitness through competitive interactions. Although some studies have focused on trait-mediated behavior such as trait-mediated dispersal, in which an organism changes its dispersal patterns due to the presence of another species, they have been mostly limited to predator-prey systems-little is known regarding their effect on other interaction systems such as mutualism. Here, we explore consequences of fragmentation and trait-mediated dispersal on coexistence of a system of two mutualists by employing a model built upon the reaction diffusion framework. To distinguish between trait-mediated dispersal and density-mediated effects, we isolate effects of trait-mediated dispersal on the mutualistic system by excluding any direct density-mediated effects in the model. Our results demonstrate that fragmentation and trait-mediated dispersal can have important impacts on coexistence of mutualists. Specifically, one species can be better able to invade and persist than the other and be crucial to the success of the other species in the patch. Matrix quality degradation can also bring about a complete reversal of the role of which species is supporting the other\u27s persistence in the patch, even as the patch size remains constant. As most mutualistic relationships are identified based on density-mediated effects, such an effect may be easily overlooked
High Responsivity and Response Speed Single-Layer Mixed-Cation Lead Mixed-Halide Perovskite Photodetectors Based on Nanogap Electrodes Manufactured on Large-Area Rigid and Flexible Substrates
No full textMixed-cation lead mixed-halide perovskites are employed as the photoactive material in single-layer solution-processed photodetectors fabricated with coplanar asymmetric nanogap Al–Au and indium tin oxide–Al electrodes. The nanogap electrodes, bearing an interelectrode distance of ≈10 nm, are patterned via adhesion lithography, a simple, low-cost, and high-throughput technique. Different electrode shapes and sizes are demonstrated on glass and flexible plastic substrates, effectively engineering the device architecture, and, along with perovskite film and material optimization, paving the way toward devices with tunable operational characteristics. The optimized coplanar nanogap junction perovskite photodetectors show responsivities up to 33 A W−1, specific detectivity on the order of 1011 Jones, and response times below 260 ns, while retaining a low dark current (0.3 nA) under −2 V reverse bias. These values outperform the vast majority of perovskite photodetectors reported so far, while avoiding the complicated fabrication steps involved in conventional multilayer device structures. This work highlights the promising potential of the proposed asymmetric nanogap electrode architecture for application in the field of flexible optoelectronics.D.G.G. and T.D.A. acknowledge financial support from the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement 706707. T.D.A. acknowledges the support from King Abdullah University of Science and Technology (KAUST)
Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells
No full textMost highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.The authors acknowledge the funding of UK Engineering and Physical Sciences Research Council (EPSRC) Plastic Electronics Doctoral Training Centre (EP/L016702/1) and KP Technology Ltd for EPSRC CASE studentships. This research was also supported by the UK EPSRC ATIP Programme Grant (EP/T028513/1) and the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2 013153)
Low Temperature Scalable Deposition of Copper(I) Thiocyanate Films via Aerosol-Assisted Chemical Vapor Deposition
No full text
