Publications
419 results found
Deledalle F, Kirchartz T, Vezie MS, et al., 2015, Understanding the Effect of Unintentional Doping on Transport Optimization and Analysis in Efficient Organic Bulk-Heterojunction Solar Cells, PHYSICAL REVIEW X, Vol: 5, ISSN: 2160-3308
- Author Web Link
- Cite
- Citations: 46
Dimitrov SD, Wheeler S, Niedzialek D, et al., 2015, Polaron pair mediated triplet generation in polymer/fullerene blends, Nature Communications, Vol: 6, ISSN: 2041-1723
Electron spin is a key consideration for the function of organic semiconductors in light-emitting diodes and solar cells, as well as spintronic applications relying on organic magnetoresistance. A mechanism for triplet excited state generation in such systems is by recombination of electron-hole pairs. However, the exact charge recombination mechanism, whether geminate or nongeminate and whether it involves spin-state mixing is not well understood. In this work, the dynamics of free charge separation competing with recombination to polymer triplet states is studied in two closely related polymer-fullerene blends with differing polymer fluorination and photovoltaic performance. Using time-resolved laser spectroscopic techniques and quantum chemical calculations, we show that lower charge separation in the fluorinated system is associated with the formation of bound electron-hole pairs, which undergo spin-state mixing on the nanosecond timescale and subsequent geminate recombination to triplet excitons. We find that these bound electron-hole pairs can be dissociated by electric fields.
Emmott CJM, Roehr JA, Campoy-Quiles M, et al., 2015, Organic photovoltaic greenhouses: a unique application for semi-transparent PV?, Energy & Environmental Science, Vol: 8, Pages: 1317-1328, ISSN: 1754-5706
Organic photovoltaics are an emerging solar power technology which embody properties such astransparency, flexibility, and rapid, roll to roll manufacture, opening the potential for unique nicheapplications. We report a detailed techno-economic analysis of one such application, namely thephotovoltaic greenhouse, and discuss whether the unique properties of the technology can provideadvantages over conventional photovoltaics. The potential for spectral selectivity through the choice ofOPV materials is evaluated for the case of a photovoltaic greenhouse. The action spectrum of typicalgreenhouse crops is used to determine the impact on crop growth of blocking different spectral rangesfrom the crops. Transfer matrix optical modelling is used to assess the efficiency and spectrally resolvedtransparency of a variety of commercially available semi-conducting polymer materials, in addition to anon-commercial low-band-gap material with absorption outside that required for crop growth. Economicanalysis suggests there could be a huge potential for OPV greenhouses if aggressive cost targets can bemet. Technical analysis shows that semi-transparent OPV devices may struggle to perform better thanopaque crystalline silicon with partial coverage, however, OPV devices using the low-band-gap materialPMDPP3T, as well as a high efficiency mid-band-gap polymer PCDTBT, can demonstrate improvedperformance in comparison to opaque, flexible thin-film modules such as CIGS. These results stress theimportance of developing new, highly transparent electrode and interlayer materials, along with highefficiency active layers, if the full potential of this application is going to be realised.
Few S, Frost JM, Nelson J, 2015, Models of charge pair generation in organic solar cells, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 17, Pages: 2311-2325, ISSN: 1463-9076
- Author Web Link
- Cite
- Citations: 139
Dattani R, Gibson KF, Few S, et al., 2015, Fullerene oxidation and clustering in solution induced by light, Journal of Colloid and Interface Science, Vol: 446, Pages: 24-30, ISSN: 1095-7103
We investigate the environmental stability of fullerene solutions by static and dynamic light scattering, FTIR, NMR and mass spectroscopies, and quantum chemical calculations. We find that visible light exposure of fullerene solutions in toluene, a good solvent, under ambient laboratory conditions results in C60 oxidation to form fullerene epoxides, and subsequently causes fullerene clustering in solution. The clusters grow with time, even in absence of further illumination, and can reach dimensions from ≈100 nm to the μm scale over ≈1 day. Static light scattering suggests that resulting aggregates are fractal, with a characteristic power law (df) that increases from approximately 1.3 to 2.0 during light exposure. The clusters are bound by weak Coulombic interactions and are found to be reversible, disintegrating by mechanical agitation and thermal stress, and reforming over time. Our findings are relevant to the solution processing of composites and organic photovoltaics, whose reproducibility and performance requires control of fullerene solution stability under storage conditions.
MacLachlan AJ, Rath T, Cappel UB, et al., 2015, Polymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance, ADVANCED FUNCTIONAL MATERIALS, Vol: 25, Pages: 409-420, ISSN: 1616-301X
- Author Web Link
- Open Access Link
- Cite
- Citations: 42
Holliday S, Ashraf RS, Nielsen CB, et al., 2015, A rhodanine flanked nonfullerene acceptor for solution-processed organic photovoltaics, Journal of the American Chemical Society, Vol: 137, Pages: 898-904, ISSN: 0002-7863
A novel small molecule, FBR, bearing 3-ethylrhodanine flanking groups was synthesized as a nonfullerene electron acceptor for solution-processed bulk heterojunction organic photovoltaics (OPV). A straightforward synthesis route was employed, offering the potential for large scale preparation of this material. Inverted OPV devices employing poly(3-hexylthiophene) (P3HT) as the donor polymer and FBR as the acceptor gave power conversion efficiencies (PCE) up to 4.1%. Transient and steady state optical spectroscopies indicated efficient, ultrafast charge generation and efficient photocurrent generation from both donor and acceptor. Ultrafast transient absorption spectroscopy was used to investigate polaron generation efficiency as well as recombination dynamics. It was determined that the P3HT:FBR blend is highly intermixed, leading to increased charge generation relative to comparative devices with P3HT:PC60BM, but also faster recombination due to a nonideal morphology in which, in contrast to P3HT:PC60BM devices, the acceptor does not aggregate enough to create appropriate percolation pathways that prevent fast nongeminate recombination. Despite this nonoptimal morphology the P3HT:FBR devices exhibit better performance than P3HT:PC60BM devices, used as control, demonstrating that this acceptor shows great promise for further optimization.
Steiner F, Foster S, Losquin A, et al., 2015, Distinguishing the influence of structural and energetic disorder on electron transport in fullerene multi-adducts, MATERIALS HORIZONS, Vol: 2, Pages: 113-119, ISSN: 2051-6347
- Author Web Link
- Cite
- Citations: 43
Manke F, Frost JM, Vaissier V, et al., 2015, Influence of a nearby substrate on the reorganization energy of hole exchange between dye molecules, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 17, Pages: 7345-7354, ISSN: 1463-9076
- Author Web Link
- Open Access Link
- Cite
- Citations: 12
Hermerschmidt F, Kalogirou AS, Min J, et al., 2015, 4<i>H</i>-1,2,6-Thiadiazin-4-one-containing small molecule donors and additive effects on their performance in solution-processed organic solar cells, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 3, Pages: 2358-2365, ISSN: 2050-7526
- Author Web Link
- Cite
- Citations: 26
Wade J, Steiner F, Niedzialek D, et al., 2014, Charge mobility anisotropy of functionalized pentacenes in organic field effect transistors fabricated by solution processing, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 2, Pages: 10110-10115, ISSN: 2050-7526
Guilbert AAY, Schmidt M, Bruno A, et al., 2014, Spectroscopic Evaluation of Mixing and Crystallinity of Fullerenes in Bulk Heterojunctions, ADVANCED FUNCTIONAL MATERIALS, Vol: 24, Pages: 6972-6980, ISSN: 1616-301X
- Author Web Link
- Cite
- Citations: 26
Madsen MV, Gevorgyan SA, Pacios R, et al., 2014, Worldwide outdoor round robin study of organic photovoltaic devices and modules, SOLAR ENERGY MATERIALS AND SOLAR CELLS, Vol: 130, Pages: 281-290, ISSN: 0927-0248
- Author Web Link
- Cite
- Citations: 21
Credgington D, Liu S-W, Nelson J, et al., 2014, In Situ Measurement of Energy Level Shifts and Recombination Rates in Subphthalocyanine/C<sub>60</sub> Bilayer Solar Cells, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 118, Pages: 22858-22864, ISSN: 1932-7447
- Author Web Link
- Cite
- Citations: 17
Foster S, Deledalle F, Mitani A, et al., 2014, Electron Collection as a Limit to Polymer:PCBM Solar Cell Efficiency: Effect of Blend Microstructure on Carrier Mobility and Device Performance in PTB7:PCBM, ADVANCED ENERGY MATERIALS, Vol: 4, ISSN: 1614-6832
- Author Web Link
- Cite
- Citations: 148
Kirchartz T, Nelson J, 2014, Device Modelling of Organic Bulk Heterojunction Solar Cells, MULTISCALE MODELLING OF ORGANIC AND HYBRID PHOTOVOLTAICS, Vol: 352, Pages: 279-324, ISSN: 0340-1022
Vaissier V, Mosconi E, Moia D, et al., 2014, Effect of Molecular Fluctuations on Hole Diffusion within Dye Monolayers, CHEMISTRY OF MATERIALS, Vol: 26, Pages: 4731-4740, ISSN: 0897-4756
- Author Web Link
- Cite
- Citations: 21
Ekins-Daukes NJ, Nelson J, 2014, Quantum Well Solar Cells, Clean Electricity from Photovoltaics, Editors: Green, Archer, Publisher: Imperial College Press, ISBN: 9781848167674
The second edition of Clean Electricity from Photovoltaics, first published in 2001, provides an updated account of the underlying science, technology and market prospects for photovoltaics.
Dattani R, Bannock JH, Fei Z, et al., 2014, A general mechanism for controlling thin film structures in all-conjugated block copolymer: fullerene blends, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 2, Pages: 14711-14719, ISSN: 2050-7488
Martinez L, Higuchi S, MacLachlan AJ, et al., 2014, Improved electronic coupling in hybrid organic-inorganic nanocomposites employing thiol-functionalized P3HT and bismuth sulfide nanocrystals, Nanoscale, Vol: 6, Pages: 10018-10026, ISSN: 2040-3372
In this study, we employ a thiol-functionalized polymer (P3HT-SH) as a leverage to tailor the nanomorphology and electronic coupling in polymer–nanocrystal composites for hybrid solar cells. The presence of the thiol functional group allows for a highly crystalline semiconducting polymer film at low thiol content and allows for improved nanomorphologies in hybrid organic–inorganic systems when employing non-toxic bismuth sulfide nanocrystals. The exciton dissociation efficiency and carrier dynamics at this hybrid heterojunction are investigated through photoluminescence quenching and transient absorption spectroscopy measurements, revealing a larger degree of polaron formation when P3HT-SH is employed, suggesting an increased electronic interaction between the metal chalcogenide nanocrystals and the thiol-functionalized P3HT. The fabricated photovoltaic devices show 15% higher power conversion efficiencies as a result of the improved nanomorphology and better charge transfer mechanism together with the higher open circuit voltages arising from the deeper energy levels of P3HT-SH.
Xu W, Zhang X, Hu Q, et al., 2014, Fluorene-based cathode interlayer polymers for high performance solution processed organic optoelectronic devices, ORGANIC ELECTRONICS, Vol: 15, Pages: 1244-1253, ISSN: 1566-1199
- Author Web Link
- Cite
- Citations: 35
Emmott CJM, Ekins-Daukes NJ, Nelson J, 2014, Dynamic carbon mitigation analysis: the role of thin-film photovoltaics, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 7, Pages: 1810-1818, ISSN: 1754-5692
- Author Web Link
- Cite
- Citations: 15
MacKenzie RCI, Goeritz A, Greedy S, et al., 2014, Theory of Stark spectroscopy transients from thin film organic semiconducting devices, PHYSICAL REVIEW B, Vol: 89, ISSN: 2469-9950
- Author Web Link
- Cite
- Citations: 12
Few S, Frost JM, Kirkpatrick J, et al., 2014, Influence of Chemical Structure on the Charge Transfer State Spectrum of a Polymer:Fullerene Complex, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 118, Pages: 8253-8261, ISSN: 1932-7447
- Author Web Link
- Cite
- Citations: 60
MacLachlan AJ, O'Mahony FTF, Sudlow AL, et al., 2014, Solution- Processed Mesoscopic Bi2S3: Polymer Photoactive Layers, CHEMPHYSCHEM, Vol: 15, Pages: 1019-1023, ISSN: 1439-4235
- Author Web Link
- Cite
- Citations: 30
Deledalle F, Shakya Tuladhar P, Nelson J, et al., 2014, Understanding the Apparent Charge Density Dependence of Mobility and Lifetime in Organic Bulk Heterojunction Solar Cells, The Journal of Physical Chemistry C, Vol: 118, Pages: 8837-8842, ISSN: 1932-7447
Abramavicius V, Vithanage DA, Devizis A, et al., 2014, Carrier motion in as-spun and annealed P3HT:PCBM blends revealed by ultrafast optical electric field probing and Monte Carlo simulations, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 2686-2692, ISSN: 1463-9076
Guilbert AAY, Frost JM, Agostinelli T, et al., 2014, Influence of Bridging Atom and Side Chains on the Structure and Crystallinity of Cyclopentadithiophene-Benzothiadiazole Polymers, CHEMISTRY OF MATERIALS, Vol: 26, Pages: 1226-1233, ISSN: 0897-4756
- Author Web Link
- Cite
- Citations: 46
Moia D, Vaissier V, Lopez-Duarte I, et al., 2014, The reorganization energy of intermolecular hole hopping between dyes anchored to surfaces, CHEMICAL SCIENCE, Vol: 5, Pages: 281-290, ISSN: 2041-6520
- Author Web Link
- Cite
- Citations: 59
Hodgkiss J, Conboy G, Hutchings G, et al., 2014, Organic photovoltaics and energy: general discussion, FARADAY DISCUSSIONS, Vol: 174, Pages: 341-355, ISSN: 1359-6640
- Author Web Link
- Cite
- Citations: 1
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.