TY - JOUR A1 - Eigmüller, Philipp A1 - Chaushev, Alexander A1 - Gillen, Edward A1 - Smith, Alexis A1 - Nielsen, Louise D. A1 - Turner, Oliver A1 - Csizmadia, Szilard A1 - Smalley, Barry A1 - Bayliss, Daniel A1 - Belardi, Claudia A1 - Bouchy, Francois A1 - Burleigh, Matthew R. A1 - Cabrera, Juan A1 - Casewell, Sarah L. A1 - Chazelas, Bruno A1 - Cooke, Benjamin F. A1 - Erikson, Anders A1 - Gansicke, Boris T. A1 - Guenther, Maximilian N. A1 - Goad, Michael R. A1 - Grange, Andrew A1 - Jackman, James A. G. A1 - Jenkins, James S. A1 - McCormac, James A1 - Moyano, Maximiliano A1 - Pollacco, Don A1 - Poppenhäger, Katja A1 - Queloz, Didier A1 - Raynard, Liam A1 - Rauer, Heike A1 - Udry, Stephane A1 - Walker, Simon. R. A1 - Watson, Christopher A. A1 - West, Richard G. A1 - Wheatley, Peter J. T1 - NGTS-5b BT - a highly inflated planet offering insights into the sub-Jovian desert JF - Astronomy and astrophysics : an international weekly journal N2 - Context. Planetary population analysis gives us insight into formation and evolution processes. For short-period planets, the sub-Jovian desert has been discussed in recent years with regard to the planet population in the mass/period and radius/period parameter space without taking stellar parameters into account. The Next Generation Transit Survey (NGTS) is optimised for detecting planets in this regime, which allows for further analysis of the sub-Jovian desert. Aims. With high-precision photometric surveys (e.g. with NGTS and TESS), which aim to detect short period planets especially around M/K-type host stars, stellar parameters need to be accounted for when empirical data are compared to model predictions. Presenting a newly discovered planet at the boundary of the sub-Jovian desert, we analyse its bulk properties and use it to show the properties of exoplanets that border the sub-Jovian desert. Methods. Using NGTS light curve and spectroscopic follow-up observations, we confirm the planetary nature of planet NGTS-5b and determine its mass. Using exoplanet archives, we set the planet in context with other discoveries. Results. NGTS-5b is a short-period planet with an orbital period of 3.3569866 +/- 0.0000026 days. With a mass of 0.229 +/- 0.037 M-Jup and a radius of 1.136 +/- 0.023 R-Jup, it is highly inflated. Its mass places it at the upper boundary of the sub-Jovian desert. Because the host is a K2 dwarf, we need to account for the stellar parameters when NGTS-5b is analysed with regard to planet populations. Conclusions. With red-sensitive surveys (e.g. with NGTS and TESS), we expect many more planets around late-type stars to be detected. An empirical analysis of the sub-Jovian desert should therefore take stellar parameters into account. KW - planets and satellites: detection KW - planets and satellites: gaseous planets Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201935206 SN - 1432-0746 VL - 625 PB - EDP Sciences CY - Les Ulis ER - TY - GEN A1 - Li, Hongguang A1 - Babu, Sukumaran Santhosh A1 - Turner, Sarah T. A1 - Neher, Dieter A1 - Hollamby, Martin J. A1 - Seki, Tomohiro A1 - Yagai, Shiki A1 - Deguchi, Yonekazu A1 - Möhwald, Helmuth A1 - Nakanishi, Takashi T1 - Alkylated-C60 based soft materials BT - regulation of selfassembly and optoelectronic properties by chain branching N2 - Derivatization of fullerene (C60) with branched aliphatic chains softens C60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84 °C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 ± 0.1%) in comparison with another compound, 10 (PCE: 0.5 ± 0.1%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 250 Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95358 SP - 1943 EP - 1951 ER - TY - JOUR A1 - Li, Hongguang A1 - Babu, Sukumaran Santhosh A1 - Turner, Sarah T. A1 - Neher, Dieter A1 - Hollamby, Martin J. A1 - Tomohito, Seki A1 - Yagai, Shiki A1 - deguchi, Yonekazu A1 - Möhwald, Helmuth A1 - Nakanishi, Takashi T1 - Alkylated-C60 based soft materials: regulation of self-assembly and optoelectronic properties by chain branching N2 - Derivatization of fullerene (C60) with branched aliphatic chains softens C60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84°C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 ñ 0.1%) in comparison with another compound, 10 (PCE: 0.5 ñ 0.1%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices. Y1 - 2013 UR - http://pubs.rsc.org/en/content/articlepdf/2013/tc/c3tc00066d U6 - https://doi.org/10.1039/C3TC00066D ER - TY - JOUR A1 - Turner, Sarah T. A1 - Pingel, Patrick A1 - Steyrleuthner, Robert A1 - Crossland, Edward J. W. A1 - Ludwigs, Sabine A1 - Neher, Dieter T1 - Quantitative analysis of bulk heterojunction films using linear absorption spectroscopy and solar cell performance JF - Advanced functional materials N2 - A fundamental understanding of the relationship between the bulk morphology and device performance is required for the further development of bulk heterojunction organic solar cells. Here, non-optimized (chloroform cast) and nearly optimized (solvent-annealed o-dichlorobenzene cast) P3HT:PCBM blend films treated over a range of annealing temperatures are studied via optical and photovoltaic device measurements. Parameters related to the P3HT aggregate morphology in the blend are obtained through a recently established analytical model developed by F. C. Spano for the absorption of weakly interacting H-aggregates. Thermally induced changes are related to the glass transition range of the blend. In the chloroform prepared devices, the improvement in device efficiency upon annealing within the glass transition range can be attributed to the growth of P3HT aggregates, an overall increase in the percentage of chain crystallinity, and a concurrent increase in the hole mobilities. Films treated above the glass transition range show an increase in efficiency and fill factor not only associated with the change in chain crystallinity, but also with a decrease in the energetic disorder. On the other hand, the properties of the P3HT phase in the solvent-annealed o-dichlorobenzene cast blends are almost indistinguishable from those of the corresponding pristine P3HT layer and are only weakly affected by thermal annealing. Apparently, slow drying of the blend allows the P3HT chains to crystallize into large domains with low degrees of intra- and interchain disorder. This morphology appears to be most favorable for the efficient generation and extraction of charges. KW - Organic electronics KW - morphology KW - solar cells KW - mobility KW - absorption spectroscopy Y1 - 2011 U6 - https://doi.org/10.1002/adfm.201101583 SN - 1616-301X VL - 21 IS - 24 SP - 4640 EP - 4652 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Li, Hongguang A1 - Babu, Sukumaran Santhosh A1 - Turner, Sarah T. A1 - Neher, Dieter A1 - Hollamby, Martin J. A1 - Seki, Tomohiro A1 - Yagai, Shiki A1 - Deguchi, Yonekazu A1 - Möhwald, Helmuth A1 - Nakanishi, Takashi T1 - Alkylated-C-60 based soft materials regulation of self-assembly and optoelectronic properties by chain branching JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - Derivatization of fullerene (C-60) with branched aliphatic chains softens C-60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C-60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84 degrees C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 + 0.1%) in comparison with another compound, 10 (PCE: 0.5 + 0.1%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C-60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices. Y1 - 2013 U6 - https://doi.org/10.1039/c3tc00066d SN - 2050-7526 VL - 1 IS - 10 SP - 1943 EP - 1951 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Moule, Adam J. A1 - Neher, Dieter A1 - Turner, Sarah T. ED - Ludwigs, S T1 - P3HT-Based solar cells: structural properties and photovoltaic performance JF - Advances in Polymer Science JF - Advances in Polymer Science N2 - Each year we are bombarded with B.Sc. and Ph.D. applications from students that want to improve the world. They have learned that their future depends on changing the type of fuel we use and that solar energy is our future. The hope and energy of these young people will transform future energy technologies, but it will not happen quickly. Organic photovoltaic devices are easy to sketch, but the materials, processing steps, and ways of measuring the properties of the materials are very complicated. It is not trivial to make a systematic measurement that will change the way other research groups think or practice. In approaching this chapter, we thought about what a new researcher would need to know about organic photovoltaic devices and materials in order to have a good start in the subject. Then, we simplified that to focus on what a new researcher would need to know about poly-3-hexylthiophene: phenyl-C61-butyric acid methyl ester blends (P3HT: PCBM) to make research progress with these materials. This chapter is by no means authoritative or a compendium of all things on P3HT: PCBM. We have selected to explain how the sample fabrication techniques lead to control of morphology and structural features and how these morphological features have specific optical and electronic consequences for organic photovoltaic device applications. KW - Free carrier generation KW - Non-geminate recombination KW - Organic solar cells Y1 - 2014 SN - 978-3-662-45145-8; 978-3-662-45144-1 U6 - https://doi.org/10.1007/12_2014_289 SN - 0065-3195 VL - 265 SP - 181 EP - 232 PB - Springer CY - Berlin ER -