54 results found
Georgiadou DG, Lin Y, Lim J, et al., 2020, 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, Advanced Functional Materials, Vol: 30, Pages: 1909758-1909758, ISSN: 1616-301X
Kumar M, Georgiadou DG, Seitkhan A, et al., 2019, Colossal Tunneling Electroresistance in Co-Planar Polymer Ferroelectric Tunnel Junctions, ADVANCED ELECTRONIC MATERIALS, ISSN: 2199-160X
Georgiadou DG, Lin Y, Lim J, et al., 2019, 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, Advanced Functional Materials, Vol: 29, Pages: 1901371-1901371, ISSN: 1616-301X
Wyatt-Moon G, Georgiadou DG, Zoladek-Lemanczyk A, et al., 2018, Flexible nanogap polymer light-emitting diodes fabricated via adhesion lithography (a-Lith), Journal of Physics: Materials, Vol: 1, ISSN: 2515-7639
We report the development of coplanar green colour organic light-emitting diodes (OLEDs) based on asymmetric nanogap electrodes fabricated on different substrates including glass and plastic. Using adhesion lithography (a-Lith) we pattern Al and Au layers acting as the cathode and anode electrodes, respectively, separated by an inter-electrode distance of <15 nm with an aspect ratio of up to 106. Spin-coating the organic light-emitting polymer poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) on top of the asymmetric Al–Au nanogap electrodes results in green light-emitting nanogap OLEDs with promising operating characteristics. We show that the scaling of the OLED's width from 4 to 200 mm can substantially improve the light output of the device without any adverse effects on the manufacturing yield. Furthermore, it is found that the light-emitting properties in the nanogap area differ from the bulk organic film, an effect attributed to confinement of the conjugated polymer chains in the nanogap channel. These results render a-Lith particularly attractive for low cost facile fabrication of nanoscale light-emitting sources and arrays on different substrates of arbitrary size.
Semple J, Georgiadou DG, Wyatt-Moon G, et al., 2018, Large-area plastic nanogap electronics enabled by adhesion lithography, npj Flexible Electronics, Vol: 2, ISSN: 2397-4621
Large-area manufacturing of flexible nanoscale electronics has long been sought by the printed electronics industry. However, the lack of a robust, reliable, high throughput and low-cost technique that is capable of delivering high-performance functional devices has hitherto hindered commercial exploitation. Herein we report on the extensive range of capabilities presented by adhesion lithography (a-Lith), an innovative patterning technique for the fabrication of coplanar nanogap electrodes with arbitrarily large aspect ratio. We use this technique to fabricate a plethora of nanoscale electronic devices based on symmetric and asymmetric coplanar electrodes separated by a nanogap < 15 nm. We show that functional devices including self-aligned-gate transistors, radio frequency diodes and rectifying circuits, multi-colour organic light-emitting nanodiodes and multilevel non-volatile memory devices, can be fabricated in a facile manner with minimum process complexity on a range of substrates. The compatibility of the formed nanogap electrodes with a wide range of solution processable semiconductors and substrate materials renders a-Lith highly attractive for the manufacturing of large-area nanoscale opto/electronics on arbitrary size and shape substrates.
Tountas M, Georgiadou DG, Zeniou A, et al., 2018, Plasma induced degradation and surface electronic structure modification of Poly(3-hexylthiophene) films, Polymer Degradation and Stability, Vol: 149, Pages: 162-172, ISSN: 0141-3910
© 2017 Elsevier Ltd Plasma treatment is an environmentally friendly solution for modifying or nanostructuring the surface of several materials including photoactive polymers. The detailed characterization of the effect of plasma treatment on chemical and optoelectronic properties of photoactive polymers is, therefore, of specific interest. Herein, the effect of the exposure of poly(3-hexylthiophene) (P3HT) thin films to plasma created in three different gases (oxygen, argon and hydrogen) was studied. A range of spectroscopic techniques, such as x-ray (XPS) and ultraviolet (UPS) photoelectron spectroscopy in conjunction with UV–vis absorption, Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopies, are employed to quantify the extent of chemical modification occurring in each particular case. It is shown that oxygen plasma treatment leads to the disruption of the π-conjugation via the direct oxidation of the sulfur atom of the thiophene ring while the aliphatic side chain remains nearly unaffected. An oxidation mechanism is proposed according to which the sulfur atom of the thiophene ring is oxidized into sulfoxides and sulfones, which subsequently degraded into sulfonates or sulfonic acids in a relatively small degree. For argon and hydrogen plasma treatments some oxidation products are detected only at the polymer surface. In all cases the polymer surface Fermi level is shifted closer to the highest occupied molecular orbital (HOMO) energy after plasma treatment indicating p-type doping arising from surface oxidation.
Chroneos A, Vasilopoulou M, Kelaidis N, et al., 2017, Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells, Scientific Reports, ISSN: 2045-2322
Wyatt-Moon G, Georgiadou DG, Semple J, et al., 2017, Deep Ultraviolet Copper(I) Thiocyanate (CuSCN) Photodetectors Based on Coplanar Nanogap Electrodes Fabricated via Adhesion Lithography., ACS Applied Materials and Interfaces, Vol: 9, Pages: 41965-41972, ISSN: 1944-8244
Adhesion lithography (a-Lith) is a versatile fabrication technique used to produce asymmetric coplanar electrodes separated by a <15 nm nanogap. Here, we use a-Lith to fabricate deep ultraviolet (DUV) photodetectors by combining coplanar asymmetric nanogap electrode architectures (Au/Al) with solution-processable wide-band-gap (3.5-3.9 eV) p-type semiconductor copper(I) thiocyanate (CuSCN). Because of the device's unique architecture, the detectors exhibit high responsivity (≈79 A W-1) and photosensitivity (≈720) when illuminated with a DUV-range (λpeak = 280 nm) light-emitting diode at 220 μW cm-2. Interestingly, the photosensitivity of the photodetectors remains fairly high (≈7) even at illuminating intensities down to 0.2 μW cm-2. The scalability of the a-Lith process combined with the unique properties of CuSCN paves the way to new forms of inexpensive, yet high-performance, photodetectors that can be manufactured on arbitrary substrate materials including plastic.
Semple J, Georgiadou DG, Wyatt-Moon G, et al., 2017, Flexible diodes for radio frequency (RF) electronics: a materials perspective, Semiconductor Science and Technology, Vol: 32, ISSN: 0268-1242
Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.
Gardelis S, Fakis M, Droseros N, et al., 2017, Energy transfer in aggregated CuInS2/ZnS core-shell quantum dots deposited as solid films, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 50, ISSN: 0022-3727
Georgiadou DG, Semple J, Anthopoulos TD, 2017, Adhesion lithography for fabrication of printed radio-frequency diodes, SPIE Newsroom
Semple J, Wyatt-Moon G, Georgiadou DG, et al., 2017, Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 64, Pages: 1973-1980, ISSN: 0018-9383
Georgiadou DG, Semple J, Wyatt-Moon G, et al., 2016, Radio frequency diodes and circuits fabricated via adhesion lithography(Conference Presentation), Printed Memory and Circuits II, Publisher: SPIE
Vasilopoulou M, Soultati A, Georgiadou DG, et al., 2016, Correction: Hydrogenated under-stoichiometric tungsten oxide anode interlayers for efficient and stable organic photovoltaics, Journal of Materials Chemistry A, Vol: 4, Pages: 17875-17875, ISSN: 2050-7496
Correction for ‘Hydrogenated under-stoichiometric tungsten oxide anode interlayers for efficient and stable organic photovoltaics’ by M. Vasilopoulou et al., J. Mater. Chem. A, 2014, 2, 1738–1749.
Vasilopoulou M, Georgiadou DG, Davazoglou D, et al., 2016, Outcoupling efficiency optimization of phosphorescent and fluorescent based hybrid red, green and blue emitting OLED devices, PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 14, NO 1-2, Vol: 14, ISSN: 1862-6351
Jelić MG, Georgiadou DG, Radanović MM, et al., 2016, Efficient electron injecting layer for PLEDs based on (PLAGH)2[ZnCl4], Optical and Quantum Electronics, Vol: 48, ISSN: 0306-8919
Herein (PLAGH)2[ZnCl4] (PLAGH? = pyridoxalaminoguanidinium cation) isintroduced as a new electron injecting layer for efficient polymer light emitting diodesbased on the green-emitting copolymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,10,3-thiadiazole)] (F8BT). The device structure is glass/ITO/PEDOT:PSS/F8BT/(PLAGH)2[ZnCl4]/Al, where (PLAGH)2[ZnCl4] was deposited from its water/methanolsolution via spin-coating. In particular, it was found that the incorporation of(PLAGH)2[ZnCl4] at the polymer/Al interface improved the luminous efficiency of thedevice (from 2.6 to 3.32 cd/A) and reduced the turn-on voltage, whereas an up to threefoldincrease in brightness (*14,106 cd/m2 for (PLAGH)2[ZnCl4], as compared to *5850 cd/m2for the reference device) was observed after annealing at 110 8C.
Karkabounas A, Georgiadou DG, Argitis P, et al., 2015, Immobilization of Lipid Substrates: Application on Phospholipase A(2) Determination, LIPIDS, Vol: 50, Pages: 1259-1271, ISSN: 0024-4201
Vasilopoulou M, Georgiadou DG, Soultati A, et al., 2015, Solution processed multi-color organic light emitting diodes for application in telecommunications, Microelectronic Engineering, Vol: 145, Pages: 21-28, ISSN: 1873-5568
Stathopoulos NA, Savaidis SP, Botsialas A, et al., 2015, Reflection and transmission calculations in a multilayer structure with coherent, incoherent and partially coherent interference, using the transmission line method, Applied Optics, Vol: 54, Pages: 1492-1504
Soultati A, Georgiadou DG, Douvas A, et al., 2014, The role of metal/metal oxide/organic anode interfaces in efficiency and stability of bulk heterojunction organic photodetectors, Microelectronic Engineering, Vol: 117, Pages: 13-17
Vasilopoulou M, Georgiadou DG, Soultati A, et al., 2014, Atomic-Layer-Deposited Aluminum and Zirconium Oxides for Surface Passivation of TiO2 in High-Efficiency Organic Photovoltaics, Advanced Energy Materials, Vol: 4
Vasilopoulou M, Georgiadou DG, Douvas AM, et al., 2014, Porphyrin oriented self-assembled nanostructures for efficient exciton dissociation in high-performing organic photovoltaics, Journal of Materials Chemistry A, Vol: 2, Pages: 182-192
Vasilopoulou M, Georgiadou DG, Soultati A, et al., 2014, Enhancing spectral response of organic photodetectors through surface modification of metal oxide electrodes, 16th International Conference on Transparent Optical Networks (ICTON 2014), Publisher: IEEE, Pages: 1-4
Douvas AM, Vasilopoulou M, Georgiadou DG, et al., 2014, Sol-gel synthesized, low-temperature processed, reduced molybdenum peroxides for organic optoelectronics applications, Journal of Materials Chemistry C, Vol: 2, Pages: 6290-6300
Vasilopoulou MA, Douvas AM, Georgiadou DG, et al., 2014, Large work function shift of organic semiconductors inducing enhanced interfacial electron transfer in organic optoelectronics enabled by porphyrin aggregated nanostructures, Nano Research, Vol: 7, Pages: 679-693
Petsalakis ID, Theodorakopoulos G, Lathiotakis NN, et al., 2014, Theoretical Study on the Electronic Structure of Triphenyl Sulfonium Salts: Electronic Excitation and Electron Transfer Processes, Chemical Physics Letters, Vol: 601, Pages: 63-68
Polydorou E, Makarona E, Soultati A, et al., 2014, Solution-processed nanostructured zinc oxide cathode interfacial layers for efficient inverted organic photovoltaics, Microelectronic Engineering, Vol: 119, Pages: 100-104
Soultati A, Douvas AM, Georgiadou DG, et al., 2014, Solution-Processed Hydrogen Molybdenum Bronzes as Highly Conductive Anode Interlayers in Efficient Organic Photovoltaics, Advanced Energy Materials, Vol: 4
Vasilopoulou M, Soultati A, Georgiadou DG, et al., 2014, Hydrogenated under-stoichiometric tungsten oxide anode interlayers for efficient and stable organic photovoltaics, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 2, Pages: 1738-1749, ISSN: 2050-7488
Vasilopoulou M, Soultati A, Georgiadou DG, et al., 2014, Hydrogenated under-stoichiometric tungsten oxide anode interlayers for efficient and stable organic photovoltaics, Journal of Materials Chemistry A, Vol: 2, Pages: 1738-1749
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