109 research outputs found
Plasmonic bulk heterojunction solar cells: the role of nanoparticle ligand coating
No full textThere has been a lot of interest regarding the influence of active-layer-incorporated plasmonic nanoparticles (NPs) in the performance of bulk heterojunction organic photovoltaic (OPV) devices, while both an increase and decrease in performance have been reported. In this paper, following a systematic approach, we demonstrate strong evidence of the critical importance of the NPs’ ligand shell on the device performance. In particular, it is argued that the plasmonic effect accountable for the performance enhancement takes place only in the case in which the NP’s core is in direct contact with the active layer polymer donor. This can be achieved with the utilization of either ligand-free NPs or NPs terminated with the same polymer donor as the active layer. Using this concept we achieved an enhanced efficiency of 7.16% in OPV devices incorporating the poly(3-hexylthiophene-2,5-diyl) (P3HT):indene-C60 bisadduct (ICBA) active layer. On the contrary, devices with ligand-terminated Au NPs show lower performance, even compared with the reference, NP-free, device due to the deteriorated active layer morphology attained, which leads to exciton quenching. These new insights into the plasmonic light-harvesting technology could shed light on the existing controversy and provide guidelines for device design and fabrication
Plasmonic backscattering effect in high-efficient organic photovoltaic devices
No full textA universal strategy for efficient light trapping through the incorporation of gold nanorods on the electron transport layer (rear) of organic photovoltaic devices is demonstrated. Utilizing the photons that are transmitted through the active layer of a bulk heterojunction photovoltaic device and would otherwise be lost, a significant enhancement in power conversion efficiency (PCE) of poly[N-9?-heptadecanyl-2,7-carbazole-alt-5,5-(4?,7?-di-2-thienyl-2?,1?,3?-benzothiadiazole)]:phenyl-C71-butyric acid methyl ester (PCDTBT:PC71BM) and poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b?]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl]] (PTB7):PC71BM by ?13% and ?8%, respectively. PCEs over 8% are reported for devices based on the PTB7:PC71BM blend. A comprehensive optical and electrical characterization of our devices to clarify the influence of gold nanorods on exciton generation, dissociation, charge recombination, and transport inside the thin film devices is performed. By correlating the experimental data with detailed numerical simulations, the near-field and far-field scattering effects are separated of gold nanorods (Au NRs), and confidently attribute part of the performance enhancement to the enhanced absorption caused by backscattering. While, a secondary contribution from the Au NRs that partially protrude inside the active layer and exhibit strong near-fields due to localized surface plasmon resonance effects is also observed but is minor in magnitude. Furthermore, another important contribution to the enhanced performance is electrical in nature and comes from the increased charge collection probability
Water-based graphene oxide inks for inkjet-printed flexible moisture energy generators
No full textWith the need for clean sustainable energy and low-waste practices rising, battery-free technologies that run on renewable ambient energy sources are an attractive solution to these environmental concerns. Herein, Graphene oxide (GO) and GO-PEDOT: PSS water-based inks were formulated from inexpensive precursor materials following user-friendly, up-scalable methods. GO-based moisture-active films were deposited on flexible lightweight substrates using inkjet printing to fabricate Moisture Energy Generators (MEG), devices that convert ambient moisture energy variation into a voltage output. The performance of the fabricated MEGs was evaluated using a custom-made automated humidity chamber, yielding an average voltage output of Vo=183 (± 1.76) mV for pure GO and Vo=194 (± 0.97) mV for GO-PEDOT: PSS, in the relative humidity range of 45-95%. We support that this study may provide fertile ground for the development of low-cost energy harvesters for self-powered portable and wearable technologies, minimising the need for batteries and reducing electronic waste.The authors would like to acknowledge the following contributors: For the ATR-IR and Raman spectroscopy measurements, Klytaimnistra Katsara (Department of Agriculture, Hellenic Mediterranean University, Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas, (FORTH), GreeceFor the XPS measurements, Emmanuel I. Spanakis (Department of Materials Science and Engineering, University of Crete, Greece)For the XPS analysis, Dimitris Tsikritzis (Department of Electrical & Computer Engineering, Hellenic Mediterranean University, Greece)For the realisation of the bending and angle measurement setup, Angelos Mastrokostas, Lazaros Anthymidis, Antonios Arvanitis (Department of Electrical & Computer Engineering, Hellenic Mediterranean University, Greece)The work has been supported by the European Union’s Horizon 2020 research and Innovation program under project EMERGE. The EMERGE project has received funding under Grant Agreement No. 101008701. The authors acknowledge the Departament de Recerca i Universitats of Generalitat de Catalunya for the grant 2021 SGR 01464.Peer reviewe
Programming the assembly of gold nanoparticles on graphene oxide sheets using DNA
No full textWe present a new method to program the covalent binding of gold nanoparticles onto graphene oxide sheets. The binding selectivity is driven by the synergy of chemically modified oligonucleotides, grafted onto the surfaces of nanoparticles and graphene oxide. In the presence of a templating complementary DNA strand, nanoparticles are brought near the surface of the graphene oxide. Once in close proximity, the DNA strands are ligated to create a permanent link between the nanoparticles and graphene oxide, ensuring stability of the system even during DNA melting conditions. Due to the selectivity and specificity of DNA, a second layer of gold nanoparticles of different size can be grafted on the top of the first layer of particles. The simplicity of this new method allows for its universal applicability when the formation of highly programmable, covalently linked hybrid nanoparticle–graphene oxide structures is a necessit
Interfacial Engineering of Perovskite Solar Cells for Improved Performance and Stability
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Resistive switching memories with enhanced durability enabled by mixed-dimensional perfluoroarene perovskite heterostructures
No full text<p><span>Characterisation dataset for “</span><span>Resistive switching memories with enhanced durability enabled by mixed-dimensional perfluoroarene perovskite heterostructures”</span><span>, DOI:</span><span>10.1039/d4nh00104d</span><span>. Data for main and supporting figures provided as *.xlsx and *.txt files.</span></p>
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Stability Enhancement in OPV: In-Situ Studies of Plasmonic Devices
No full textExtended Abstract Bulk heterojunction (BHJ) organic photovoltaic (OPV) devices attracted considerable research interest due to several significant characteristics, such as their flexibility, lightweight, low environmental impact and reduced cost of large-scale production. A key aspect in OPVs is improving the device long-term stability: in this contest, novel organic materials and cell architectures are developed and a significant task is played by the development of in-situ diagnostics able to detect the driving mechanisms of device degradation, considering that the optical and transport properties of the device active elements depend on the structural, morphological and interfacial characteristics. In this work we discuss our recent results on devices incorporating metallic nanoparticles (NPs) in the photoactive layer, in order to take advantage of the ability of the metallic NPs to rise the BHJ optical absorption by the excitation of Localized Surface Plasmon Resonance. Both plasmonic and reference systems are studied and a powerful approach for addressing the role of structural/morphological and interface properties of the different layers and their interfaces is used: time-resolved Energy Dispersive X-ray Reflectivity/Diffraction (EDXR/EDXD) techniques are applied jointly with in-situ atomic force microscopy (AFM). The results of such unconventional approach, based on time-resolved EDXR/AFM cross-monitoring, showed that incorporating metallic NPs allowed to control both the bulk and the interface morphological degradation pathways References [1] B. Paci, A. Generosi, V. Rossi Albertini, G.Spyropoulos, E. Stratakis, E. Kymakis, "Enhancement of photo/thermal stability of organic bulk heterojunction photovoltaic devices via gold nanoparticles doping of the active layer,"
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