Ellen Moons | Karlstad University (original) (raw)

Papers by Ellen Moons

Organic Electronics, Feb 1, 2017

Organic photovoltaic cells based on ternary blends of materials with complementary properties rep... more Organic photovoltaic cells based on ternary blends of materials with complementary properties represent an approach to improve the photon-absorption and/or charge transport within the devices. However, the more complex nature of the ternary system, i.e. in diversity of materials' properties and morphological features, complicates the understanding of the processes behind such optimizations. Here, organic photovoltaic cells with wider absorption spectrum composed of two electron-donor polymers, F8T2, poly(9,9-dioctylfluorene-alt-bithiophene), and PTB7, 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

Verhandlungen der Deutschen Physikalischen Gesellschaft, Jul 1, 2009

C1s NEXAFS investigations of PC60BM exposed to oxygen: a novel approach for the comparison of com... more C1s NEXAFS investigations of PC60BM exposed to oxygen: a novel approach for the comparison of computed and experimental spectra

Nanoscale, 2020

The crystallisation tendency of nonfullerene acceptors was finely controlled by extending the fus... more The crystallisation tendency of nonfullerene acceptors was finely controlled by extending the fused end groups and the nanostructure and device performances of polymer solar cells were optimized by such molecular engineering.

Energy and Environmental Science, 2020

Obtaining both high open-circuit voltage (V oc) and short-circuit current density (J sc) has been... more Obtaining both high open-circuit voltage (V oc) and short-circuit current density (J sc) has been a major challenge for efficient all-polymer solar cells (all-PSCs). Herein, we developed a polymer acceptor PF5-Y5 with excellent optical absorption capability (onset extending to B880 nm and maximum absorption coefficient exceeding 10 5 cm À1 in a film), high electron mobility (3.18 Â 10 À3 cm 2 V À1 s À1) and high LUMO level (À3.84 eV) to address such a challenge. As a result, the PBDB-T:PF5-Y5-based all-PSCs achieved a high power conversion efficiency of up to 14.45% with both a high V oc (0.946 V) and a high J sc (20.65 mA cm À2), due to the high and broad absorption coverage, small energy loss (0.57 eV) and efficient charge separation and transport in the device, which are among the best values in the all-PSC field. In addition, the all-PSC shows a B15% improvement in PCE compared to its counterpart small molecule acceptor (Y5)-based device. Our results suggest that PF5-Y5 is a very promising polymer acceptor candidate for applications in efficient all-PSCs. Broader context Different from state-of-the-art organic solar cells consisting of p-type polymer donors and n-type small molecule acceptors, all-polymer solar cells (all-PSCs) have such irreplaceable advantages as excellent morphological stability and mechanical robustness, and thus are considered to be more practically compatible with large scale production via roll-to-roll printing technology, therefore showing great prospects in their future commercialization. However, the currently reported leading PCEs for almost all all-PSCs in the literature have gained either high open-circuit voltage (V oc) or high short-circuit current density (J sc) only, resulting in unsatisfactory power conversion efficiencies (PCEs), which is mainly due to the lack of high-performance polymer acceptors. Herein, a low bandgap polymer acceptor PF5-Y5 with excellent optoelectronic properties was developed by coupling an electron-deficient benzothiadiazole-fused building block and electron-rich thienyl-benzodithiophene, and the related all-PSCs achieved a high PCE of up to 14.45% with a simultaneously realized high V oc of 0.946 V and high J sc of 20.65 mA cm À2 , which are among the best values in the all-PSC field.

Journal of Physical Chemistry Letters, Dec 13, 2022

1-Chloronaphthalene (CN) has been a common solvent additive in both fullerene-and nonfullerene-ba... more 1-Chloronaphthalene (CN) has been a common solvent additive in both fullerene-and nonfullerene-based organic solar cells. In spite of this, its working mechanism is seldom investigated, in particular, during the drying process of bulk heterojunctions composed of a donor:acceptor mixture. In this work, the role of CN in all-polymer solar cells is investigated by in situ spectroscopies and ex situ characterization of blade-coated PBDB-T:PF5-Y5 blends. Our results suggest that the added CN promotes self-aggregation of polymer donor PBDB-T during the drying process of the blend film, resulting in enhanced crystallinity and hole mobility, which contribute to the increased fill factor and improved performance of PBDB-T:PF5-Y5 solar cells. Besides, the nonradiative energy loss of the corresponding device is also reduced by the addition of CN, corresponding to a slightly increased open-circuit voltage. Overall, our observations deepen our understanding of the drying dynamics, which may guide further development of all-polymer solar cells.

Journal of Materials Chemistry C

Donor polymer PBDB-T and acceptor polymer PF5-Y5 form D–A complexes in solution, as confirmed by ... more Donor polymer PBDB-T and acceptor polymer PF5-Y5 form D–A complexes in solution, as confirmed by combined absorption, excitation, and emission spectroscopy of blend solutions.

Solar RRL

All-polymer solar cells (all-PSCs) have attracted extensive attention due to the thermal and mech... more All-polymer solar cells (all-PSCs) have attracted extensive attention due to the thermal and mechanical stability of polymers. [1-5] The limiting factors for all-PSCs are mainly incurred by the small electron mobility of polymer acceptors and strong phase separation upon evaporation of the solvent. [2,6] It is known that the emerging non-fullerene acceptors (NFAs), such as ITIC and Y6, have strong absorption in the near-infrared region and excellent electron-transport properties, which enables power conversion efficiencies (PCEs) of organic solar cells (OSCs) exceeding 19%. [7-10] Recently, novel polymer acceptors have been synthesized by polymerizing NFAs to synergize the merits of NFAs and conjugated polymers. [11-13] The PCEs of all-PSCs employing such polymerized NFAs were promoted to above 16%. [14,15] However, high-efficient all-PSCs are commonly fabricated via spin-coating in inert atmosphere, which is not compatible with upscaling of solar module production. To realize the commercialization of OSCs in the future, continuous largearea-coating techniques like blade-coating or slot-die-coating are required. Nowadays, the performance of OSCs printed in air still lags behind those of OSCs spin-coated in a glove box.

Communications in Nonlinear Science and Numerical Simulation

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Proceedings of the nanoGe Spring Meeting 2022, 2022

ACS Energy Letters, 2021

Vacuum deposition methods are increasingly applied to the preparation of perovskite films and dev... more Vacuum deposition methods are increasingly applied to the preparation of perovskite films and devices, in view of the possibility to prepare multilayer structures at low temperature. Vacuum-deposited, wide-bandgap solar cells based on mixed-cation and mixed-anion perovskites have been scarcely reported, due to the challenges associated with the multiple-source processing of perovskite thin films. In this work, we describe a four-source vacuum deposition process to prepare wide-bandgap perovskites of the type FA 1−n Cs n Pb-(I 1−x Br x) 3 with a tunable bandgap and controlled morphology, using FAI, CsI, PbI 2 , and PbBr 2 as the precursors. The simultaneous sublimation of PbI 2 and PbBr 2 allows the relative Br/Cs content to be decoupled and controlled, resulting in homogeneous perovskite films with a bandgap in the 1.7−1.8 eV range and no detectable halide segregation. Solar cells based on 1.75 eV bandgap perovskites show efficiency up to 16.8% and promising stability, maintaining 90% of the initial efficiency after 2 weeks of operation.

Chemistry of Materials, 2018

Nanoparticle organic photovoltaics, a subfield of organic photovoltaics (OPV), has attracted incr... more Nanoparticle organic photovoltaics, a subfield of organic photovoltaics (OPV), has attracted increasing interest in recent years due to the eco-friendly fabrication of solar modules afforded by colloidal ink technology. Importantly, using this approach it is now possible to engineer the microstructure of the light absorbing/charge generating layer of organic photovoltaics; decoupling film morphology from film deposition. In this study, single-component nanoparticles of poly(3-hexylthiophene) (P3HT) and phenyl-C 61 butyric acid methyl ester (PC 61 BM) were synthesized and used to generate a two-phase microstructure with control over domain size prior to film deposition. Scanning transmission X-ray microscopy (STXM) and electron microscopy were used to characterize the thin film morphology. Uniquely, the measured microstructure was a direct input for a nanoscopic kinetic Monte Carlo (KMC) model allowing us to assess exciton transport properties that are experimentally inaccessible in these singlecomponent particles. Photoluminescence, UV−vis spectroscopy measurements, and KMC results of the nanoparticle thin films enabled the calculation of an experimental exciton dissociation efficiency (η ED) of 37% for the two-phase microstructure. The glass transition temperature (T g) of the materials was characterized with dynamic mechanical thermal analysis (DMTA) and thermal annealing led to an increase in η ED to 64% due to an increase in donor−acceptor interfaces in the thin film from both sintering of neighboring opposite-type particles in addition to the generation of a third mixed phase from diffusion of PC 61 BM into amorphous P3HT domains. As such, this study demonstrates the higher level of control over donor−acceptor film morphology enabled by customizing nanoparticulate colloidal inks, where the optimal three-phase film morphology for an OPV photoactive layer can be designed and engineered.

Green Chemistry, 2019

Realising bicontinuous interpenetrating network morphologies – with nanoscale phase separation – ... more Realising bicontinuous interpenetrating network morphologies – with nanoscale phase separation – for donor–acceptor material systems processed from environmentally-friendlier ink formulations.

Nordic Pulp & Paper Research Journal, 2015

The permeability of dispersion barriers produced from polyvinyl alcohol (PVOH) and kaolin clay bl... more The permeability of dispersion barriers produced from polyvinyl alcohol (PVOH) and kaolin clay blends coated onto polymeric supports has been studied by employing two different measurement methods: the oxygen transmission rate (OTR) and the ambient oxygen ingress rate (AOIR). Coatings with different thicknesses and kaolin contents were studied. Structural information of the dispersion-barrier coatings was obtained by Fourier transform infrared spectroscopy (FTIR) spectroscopy and scanning electron microscopy (SEM). These results showed that the kaolin content influences both the orientation of the kaolin and the degree of crystallinity of the PVOH coating. Increased kaolin content increased the alignment of the kaolin platelets to the basal plane of the coating. Higher kaolin content was accompanied by higher degree of crystallinity of the PVOH. The barrier thickness proved to be less important in the early stages of the mass transport process, whereas it had a significant influence on the steady-state permeability. The results from this study demonstrate the need for better understanding of how permeability is influenced by (chemical and physical) structure.

SPIE Proceedings, 2015

The quinoxaline-based polymer TQ1 (poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thioph... more The quinoxaline-based polymer TQ1 (poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5- diyl]) is a promising candidate as electron donor in organic solar cells. In combination with the electron acceptor [6,6]- phenyl-C71- butyric acid methyl ester (PC70BM), TQ1 has resulted in solar cells with power conversion efficiencies of 7 %. We have studied TQ1 films, with and without PC70BM, spin-casted from different solvents, by fluorescence spectroscopy and UV/VIS absorption spectroscopy. We used chloroform (CF), chlorobenzene (CB), and odichlorobenzene (o-DCB) as solvents for the coating solutions and 1-chloronaphthalene (CN) as solvent additive. CN addition has been shown to enhance photo-conversion efficiency of these solar cells. Phase-separation causes lateral domain formation in the films and the domain size depends on the solvent . These morphological differences coincide with changes in the spectroscopic patterns of the films. From a spectroscopic point of view, TQ1 acts as fluorescent probe and PC70BM as quencher. The degree of fluorescence quenching is coupled to the morphology through the distance between TQ1 and PC70BM. Furthermore, if using a bad solvent for PC70BM, morphological regions rich in the fullerene yield emission characteristic for aggregated PC70BM. Clear differences were found, comparing the TQ1:PC70BM blend films casted from different solvents and at different ratios between the donor and acceptor. The morphology also influences the UV/VIS absorption spectra, yielding further information on the composition. The results show that fluorescence and UV/VIS absorption spectroscopy can be used to detect aggregation in blended films and that these methods extend the morphological information beyond the scale accessible with microscopy.

Journal of Materials Chemistry A, 2015

Solvent vapor annealing on crystalline DIP and amorphous DBP induces morphological changes, which... more Solvent vapor annealing on crystalline DIP and amorphous DBP induces morphological changes, which can improve organic solar cell efficiency.