16 results on '"Hermerschmidt, F."'
Search Results
2. High performance organic light-emitting diodes employing ITO-free and flexible TiOx/Ag/Al:ZnO electrodes
- Author
-
Kinner, L., Dimopoulos, T., Ligorio, G., List Kratochvil, E.J.W., and Hermerschmidt, F.
- Subjects
540 Chemie und zugeordnete Wissenschaften ,ddc:540 ,Photovoltaics and Wind Energy - Abstract
The broad application of flexible optoelectronic devices is still hampered by the lack of an ITO free and highly flexible transparent electrode. Dielectric metal dielectric DMD transparent electrodes are promising candidates to replace ITO, especially in flexible devices due to their mechanical stability to bending, high optical transmittance and low sheet resistance lt;6 amp; 937; sq amp; 8722;1 . This paper reports on organic light emitting diodes OLEDs employing a DMD electrode, specifically TiOx Ag Al ZnO doped with 2 wt Al2O3 fabricated by sputter deposition, together with a solution processed organic polymeric emitting layer. The electrodes were sputtered without substrate heating on rigid glass and flexible polyethylene terephthalate PET . The results showed that the OLED devices on the DMD electrodes outperform the OLEDs on commercial ITO substrates in terms of maximum luminance as well as current efficacy. Specifically, DMD based devices achieve up to 30 higher current efficacy on glass and up to 260 higher efficacy on PET, as compared to the ITO based reference devices. Maximum luminance reaches up to 100 amp; 8198;000 cd m amp; 8722;2 for the DMD based OLEDs on glass and 43 amp; 8198;000 cd m amp; 8722;2 for those on PET. This performance is due to the low sheet resistance of the electrodes combined with efficient light outcoupling and shows the potential of DMDs to replace ITO in optoelectronic devices. This outstanding type of optoelectronic device paves the way for the future high throughput production of flexible display and photovoltaic devices
- Published
- 2021
3. Up-scalable ITO-free organic light emitting diodes based on embedded inkjet-printed copper grids
- Author
-
Pozov, S.M., Schider, G., Voigt, S., Ebert, F., Popovic, K., Hermerschmidt, F., Georgiou, E., Burgués-Ceballos, I., Kinner, L., Nees, D., Stadlober, B., Rapley, C., Ward, R., Choulis, S.A., List-Kratochvil, E.J.W., Boeffel, C., and Publica
- Abstract
We report on ITO-free OLEDS with a transparent hybrid Cu nanoparticle grid/PEDOT:PSS electrode processed in ambient conditions. An experimentally based methodology was implemented, where studies on alternative PEDOT:PSS derivatives and Cu grid design were performed, to gradually increase the efficiency of lab scale ITO-free OLEDs. To further increase electrode performance, inkjet-printed (IJP) Cu-grids are embedded to flatten the electrode, reduce leakage current and enhance homogeneity and efficiency. Finally, embedded Cu based ITO-free OLEDs showed current and power efficiencies comparable to reference ITO-based OLEDs. Methods to manufacture large area flat embedded IJP Cu-electrodes on glass and flexible substrates are presented and upscaling prospects of the proposed ITO-free electrode are discussed.
- Published
- 2019
4. 4H-1,2,6-Thiadiazin-4-one-containing small molecule donors and additive effects on their performance in solution-processed organic solar cells
- Author
-
Hermerschmidt, F., Kalogirou, Andreas S., Min, J., Zissimou, Georgia A., Tuladhar, S. M., Ameri, T., Faber, H., Itskos, Grigorios, Choulis, Stelios A., Anthopoulos, T. D., Bradley, D. D. C., Nelson, J., Brabec, C. J., Koutentis, Panayiotis Andreas, Itskos, Grigorios [0000-0003-3971-3801], Koutentis, Panayiotis Andreas [0000-0002-4652-7567], Zissimou, Georgia A. [0000-0003-4821-9469], Kalogirou, Andreas S. [0000-0002-5476-5805], and Choulis, Stelios A. [0000-0002-7899-6296]
- Subjects
Solar cells ,Systematic variation ,Electron mobility ,Fullerene ,Materials science ,Organic solar cell ,Technische Fakultät ,Silicones ,Bulk heterojunction solar cells ,Hole mobility ,Power conversion efficiencies ,Polymer solar cell ,Solution-processed ,Materials Chemistry ,Side chain ,Organic chemistry ,Alkyl ,chemistry.chemical_classification ,Energy conversion efficiency ,Donor acceptor donors ,technology, industry, and agriculture ,General Chemistry ,Electrical Engineering - Electronic Engineering - Information Engineering ,Acceptor ,Alkyl side chains ,Polydimethylsiloxane PDMS ,chemistry ,Chemical engineering ,Heterojunctions ,Engineering and Technology ,Fullerenes ,ddc:600 - Abstract
The optical, electrochemical, morphological and transport properties of a series of thiadiazinone (acceptor) and (thienyl)carbazoles (donor) containing π-extended donor-acceptor-donors (D-A-D) are presented. Systematic variations in the number of the thienyl units, the choice of branched or straight alkyl side chains and the use of a processing additive demonstrate their use as electron donors in bulk heterojunction solar cells blended with fullerene acceptors. The best power conversion efficiency (PCE) of 2.7% is achieved by adding to the D-A-D 3:fullerene blend a polydimethylsiloxane (PDMS) additive, that improves the morphology and doubles the hole mobility within the D-A-D:fullerene blend. © The Royal Society of Chemistry. 3 10 2358 2365 Cited By :7
- Published
- 2015
5. Inkjet printing processing conditions for bulk-heterojunction solar cells using two high-performing conjugated polymer donors
- Author
-
Hermerschmidt, F., Papagiorgis, Panagiotis, Savva, Achilleas, Christodoulou, Chris C., Itskos, Grigorios, Choulis, Stelios A., Itskos, Grigorios [0000-0003-3971-3801], Choulis, Stelios A. [0000-0002-7899-6296], and Christodoulou, Chris C. [0000-0001-9398-5256]
- Subjects
Morphology ,Silicon ,Fullerene ,Materials science ,1 ,3-benzothiadiazole ,Organic solar cell ,Band gap ,Conjugated system ,Conjugated polymers ,Power conversion efficiencies ,Polymer solar cell ,Processing condition ,Bulk-heterojunction solar cells ,Low band gap conjugated polymers ,chemistry.chemical_classification ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,Printed electronics ,Electron acceptor ,Electrical Engineering - Electronic Engineering - Information Engineering ,Organic photovoltaic devices ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Organic photovoltaics ,Heterojunctions ,Optoelectronics ,Engineering and Technology ,Fullerenes ,Conversion efficiency ,Ink jet printing ,business ,Inkjet printing and processing - Abstract
We report the processing conditions for inkjet-printed active layers of organic photovoltaic (OPV) devices comprising bulk-heterojunction blends of the low bandgap conjugated polymer poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b: 2′,3′-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1, 3-benzothiadiazole)-5,5′-diyl] (Si-PCPDTBT) as well as poly[N-9′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′, 7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) used as electron donors with [6,6]-phenyl-C71-butyric acid methyl ester (PC 70BM) as electron acceptor. By controlling the inkjet printing processing conditions, we gain a significant improvement in device power conversion efficiency (PCE) to previously reported work using these materials. We obtain Si-PCPDTBT:fullerene and PCDTBT:fullerene-based inkjet-printed OPVs with power conversion efficiency of ~3% and ~4%, respectively. © 2014 Elsevier B.V. 130 474 480 Cited By :10
- Published
- 2014
6. Size-dependent charge transfer in blends of Pbs quantum dots with a low-gap silicon-bridged copolymer
- Author
-
Itskos, Grigorios, Papagiorgis, Panagiotis, Tsokkou, Demetra, Othonos, Andreas S., Hermerschmidt, F., Economopoulos, Solon P., Yarema, M., Heiss, W., Choulis, Stelios A., Itskos, Grigorios [0000-0003-3971-3801], Othonos, Andreas S. [0000-0003-0016-9116], Choulis, Stelios A. [0000-0002-7899-6296], and Economopoulos, Solon P. [0000-0002-2609-4602]
- Subjects
Silicon ,Materials science ,Fullerene ,Polymers ,Exciton ,Bulk heterojunction ,quantum dots ,Fullerene derivative ,Electron ,Polymer excitons ,Electron transfer ,Polymer blends ,Semiconductor quantum dots ,General Materials Science ,Semiconducting organic compounds ,organic semiconductors ,photophysics ,Renewable Energy, Sustainability and the Environment ,business.industry ,Mechanical Engineering ,PbS quantum dots ,Heterojunction ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Organic semiconductor ,Semiconducting lead compounds ,Nanocrystal ,Quantum-dot size ,Quantum dot ,solar cells ,Heterojunctions ,Nanocrystal sizes ,Optoelectronics ,Engineering and Technology ,photodetectors ,Excitons ,Fullerenes ,business - Abstract
The photophysics of bulk heterojunctions of a high-performance, low-gap silicon-bridged dithiophene polymer with oleic acid capped PbS quantum dots (QDs) are studied to assess the material potential for light harvesting in the visible- and IR-light ranges. By employing a wide range of nanocrystal sizes, systematic dependences of electron and hole transfer on quantum-dot size are established for the first time on a low-gap polymer-dot system. The studied system exhibits type II band offsets for dot sizes up to ca. 4 nm, whch allow fast hole transfer from the quantum dots to the polymer that competes favorably with the intrinsic QD recombination. Electron transfer from the polymer is also observed although it is less competitive with the fast polymer exciton recombination for most QD sizes studied. The incorporation of a fullerene derivative provides efficient electron-quenching sites that improve interfacial polymer-exciton dissociation in ternary polymer-fullerene-QD blends. The study indicates that programmable band offsets that allow both electron and hole extraction can be produced for efficient light harvesting based on this low-gap polymer-PbS QD composite. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 3 11 1490 1499 Cited By :18
- Published
- 2013
7. Novel Cu/ZnO catalyst precursors for synthesis of methanol
- Author
-
Hermerschmidt, F.
- Published
- 2009
8. Additive-assisted supramolecular manipulation of polymer:fullerene blend phase morphologies and its influence on photophysical processes
- Author
-
Buchaca-Domingo, E., primary, Ferguson, A. J., additional, Jamieson, F. C., additional, McCarthy-Ward, T., additional, Shoaee, S., additional, Tumbleston, J. R., additional, Reid, O. G., additional, Yu, L., additional, Madec, M.-B., additional, Pfannmöller, M., additional, Hermerschmidt, F., additional, Schröder, R. R., additional, Watkins, S. E., additional, Kopidakis, N., additional, Portale, G., additional, Amassian, A., additional, Heeney, M., additional, Ade, H., additional, Rumbles, G., additional, Durrant, J. R., additional, and Stingelin, N., additional
- Published
- 2014
- Full Text
- View/download PDF
9. Highly efficient indium tin oxide-free organic photovoltaics using inkjet-printed silver nanoparticle current collecting grids
- Author
-
Neophytou, M., primary, Hermerschmidt, F., additional, Savva, A., additional, Georgiou, E., additional, and Choulis, S. A., additional
- Published
- 2012
- Full Text
- View/download PDF
10. Bicolour, large area, inkjet-printed metal halide perovskite light emitting diodes.
- Author
-
Schröder VRF, Fratzscher N, Zorn Morales N, Rühl DS, Hermerschmidt F, Unger EL, and List-Kratochvil EJW
- Abstract
We demonstrate a bicoloured metal halide perovskite (MHP) light emitting diode (LED) fabricated in two sequential inkjet printing steps. By adjusting the printing parameters, we selectively and deliberately redissolve and recrystallize the first printed emissive layer to add a pattern emitting in a different color. The red light emitting features (on a green light emitting background) have a minimum size of 100 μm and originate from iodide-rich domains in a phase-segregated, mixed MHP. This phase forms between the first layer, a bromide-based MHP, which is partially dissolved by printing, and the second layer, an iodide-containing MHP. With an optimised printing process we can retain the active layer integrity and fabricate bicolour, large area MHP-based LEDs with up to 1600 mm
2 active area. The two emission peaks at 535 nm and 710 nm are well separated and produce a strong visual contrast.- Published
- 2024
- Full Text
- View/download PDF
11. Doubly Bridged Anthracenes: Blue Emitters for OLEDs.
- Author
-
Ludwig P, Mayer J, Ahrens L, Rominger F, Ligorio G, Hermerschmidt F, List-Kratochvil EJW, Freudenberg J, and Bunz UHF
- Abstract
The photooxidative stability of a series of doubly bridged anthracenes was evaluated after their preparation via twofold macrocyclization of a bis(resorcinyl)anthracene. Lightfastness correlates with the energy levels of the highest occupied molecular orbital (HOMO), resulting in superior stability of the tetraesters compared to the tetraethers. The lengths and steric demand of the linker only plays a minor role for the ester-based compounds, which can be prepared in reasonable yields and thus tested in proof-of-concept organic light-emitting diodes. Double ester-bridging allows deep blue electro-luminescence, highlighting the importance of the choice of the functional groups used for macrocyclization., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)
- Published
- 2024
- Full Text
- View/download PDF
12. Large area inkjet-printed metal halide perovskite LEDs enabled by gas flow assisted drying and crystallization.
- Author
-
Schröder VRF, Fratzscher N, Mathies F, Nandayapa ER, Hermerschmidt F, Unger EL, and List-Kratochvil EJW
- Abstract
We demonstrate the upscaling of inkjet-printed metal halide perovskite light-emitting diodes. To achieve this, the drying process, critical for controlling the crystallization of the perovskite layer, was optimized with an airblade-like slit nozzle in a gas flow assisted vacuum drying step. This yields large, continuous perovskite layers in light-emitting diodes with an active area up to 1600 mm
2 .- Published
- 2023
- Full Text
- View/download PDF
13. High performance organic light-emitting diodes employing ITO-free and flexible TiO x /Ag/Al:ZnO electrodes.
- Author
-
Kinner L, Dimopoulos T, Ligorio G, List-Kratochvil EJW, and Hermerschmidt F
- Abstract
The broad application of flexible optoelectronic devices is still hampered by the lack of an ITO-free and highly flexible transparent electrode. Dielectric/metal/dielectric (DMD) transparent electrodes are promising candidates to replace ITO, especially in flexible devices due to their mechanical stability to bending, high optical transmittance and low sheet resistance (<6 Ω sq
-1 ). This paper reports on organic light emitting diodes (OLEDs) employing a DMD electrode, specifically TiOx /Ag/Al:ZnO (doped with 2 wt% Al2 O3 ) fabricated by sputter deposition, together with a solution-processed organic polymeric emitting layer. The electrodes were sputtered without substrate heating on rigid glass and flexible polyethylene terephthalate (PET). The results showed that the OLED devices on the DMD electrodes outperform the OLEDs on commercial ITO substrates in terms of maximum luminance as well as current efficacy. Specifically, DMD-based devices achieve up to 30% higher current efficacy on glass and up to 260% higher efficacy on PET, as compared to the ITO-based reference devices. Maximum luminance reaches up to 100 000 cd m-2 for the DMD-based OLEDs on glass and 43 000 cd m-2 for those on PET. This performance is due to the low sheet resistance of the electrodes combined with efficient light outcoupling and shows the potential of DMDs to replace ITO in optoelectronic devices. This outstanding type of optoelectronic device paves the way for the future high throughput production of flexible display and photovoltaic devices., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)- Published
- 2021
- Full Text
- View/download PDF
14. Influence of the Hole Transporting Layer on the Thermal Stability of Inverted Organic Photovoltaics Using Accelerated-Heat Lifetime Protocols.
- Author
-
Hermerschmidt F, Savva A, Georgiou E, Tuladhar SM, Durrant JR, McCulloch I, Bradley DDC, Brabec CJ, Nelson J, and Choulis SA
- Abstract
High power conversion efficiency (PCE) inverted organic photovoltaics (OPVs) usually use thermally evaporated MoO
3 as a hole transporting layer (HTL). Despite the high PCE values reported, stability investigations are still limited and the exact degradation mechanisms of inverted OPVs using thermally evaporated MoO3 HTL remain unclear under different environmental stress factors. In this study, we monitor the accelerated lifetime performance under the ISOS-D-2 protocol (heat conditions 65 °C) of nonencapsulated inverted OPVs based on the thiophene-based active layer materials poly(3-hexylthiophene) (P3HT), 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), and thieno[3,2-b]thiophene-diketopyrrolopyrrole (DPPTTT) blended with [6,6]-phenyl C71 -butyric acid methyl ester (PC[70]BM). The presented investigation of degradation mechanisms focus on optimized P3HT:PC[70]BM-based inverted OPVs. Specifically, we present a systematic study on the thermal stability of inverted P3HT:PC[70]BM OPVs using solution-processed poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and evaporated MoO3 HTL. Using a series of measurements and reverse engineering methods, we report that the P3HT:PC[70]BM/MoO3 interface is the main origin of failure of the P3HT:PC[70]BM-based inverted OPVs under intense heat conditions, a trend that is also observed for the other two thiophene-based polymers used in this study.- Published
- 2017
- Full Text
- View/download PDF
15. High-Performing Polycarbazole Derivatives for Efficient Solution-Processing of Organic Solar Cells in Air.
- Author
-
Burgués-Ceballos I, Hermerschmidt F, Akkuratov AV, Susarova DK, Troshin PA, and Choulis SA
- Subjects
- Air, Molecular Weight, Thiadiazoles chemistry, Thiophenes chemistry, Carbazoles chemistry, Electric Power Supplies, Polymers chemistry, Solar Energy
- Abstract
The application of conjugated materials in organic photovoltaics (OPVs) is usually demonstrated in lab-scale spin-coated devices that are processed under controlled inert conditions. Although this is a necessary step to prove high efficiency, testing of promising materials in air should be done in the early stages of research to validate their real potential for low-cost, solution-processed, and large-scale OPVs. Also relevant for approaching commercialization needs is the use of printing techniques that are compatible with upscaling. Here, solution processing of organic solar cells based on three new poly(2,7-carbazole) derivatives is efficiently transferred, without significant losses, to air conditions and to several deposition methods using a simple device architecture. High efficiencies in the range between 5.0 % and 6.3 % are obtained in (rigid) spin-coated, doctor-bladed, and (flexible) slot-die-coated devices, which surpass the reference devices based on poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT). In contrast, inkjet printing does not provide reliable results with the presented polymers, which is attributed to their high molecular weight. When the device area in the best-performing system is increased from 9 mm(2) to 0.7 cm(2), the efficiency drops from 6.2 % to 5.0 %. Photocurrent mapping reveals inhomogeneous current generation derived from changes in the thickness of the active layer., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
- Full Text
- View/download PDF
16. Knowledge-based development of a nitrate-free synthesis route for Cu/ZnO methanol synthesis catalysts via formate precursors.
- Author
-
Behrens M, Kissner S, Girsgdies F, Kasatkin I, Hermerschmidt F, Mette K, Ruland H, Muhler M, and Schlögl R
- Abstract
High-performance Cu/ZnO/(Al(2)O(3)) methanol synthesis catalysts are conventionally prepared by co-precipitation from nitrate solutions and subsequent thermal treatment. A new synthesis route is presented, which is based on similar preparation steps and leads to active catalysts, but avoids nitrate contaminated waste water.
- Published
- 2011
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.