Importance of the Donor: Fullerene Intermolecular Arrangement for High-Efficiency Organic Photovoltaics

The performance of organic photovoltaic (OPV) material systems are hypothesized to depend strongly on the intermolecular arrangements at the donor:fullerene interfaces. A review of some of the most efficient polymers utilized in polymer:fullerene PV devices, combined with an analysis of reported polymer donor materials wherein the same conjugated backbone was used with varying alkyl substituents, supports this hypothesis. Specifically, the literature shows that higher-performing donor–acceptor type polymers generally have acceptor moieties that are sterically accessible for interactions with the fullerene derivative, whereas the corresponding donor moieties tend to have branched alkyl substituents that sterically hinder interactions with the fullerene. To further explore the idea that the most beneficial polymer:fullerene arrangement involves the fullerene docking with the acceptor moiety, a family of benzo[1,2-b:4,5-b′]dithiophene–thieno[3,4-c]pyrrole-4,6-dione polymers (PBDTTPD derivatives) was synthesized and tested in a variety of PV device types with vastly different aggregation states of the polymer. In agreement with our hypothesis, the PBDTTPD derivative with a more sterically accessible acceptor moiety and a more sterically hindered donor moiety shows the highest performance in bulk-heterojunction, bilayer, and low-polymer concentration PV devices where fullerene derivatives serve as the electron-accepting materials. Furthermore, external quantum efficiency measurements of the charge-transfer state and solid-state two-dimensional (2D) 13C{1H} heteronuclear correlation (HETCOR) NMR analyses support that a specific polymer:fullerene arrangement is present for the highest performing PBDTTPD derivative, in which the fullerene is in closer proximity to the acceptor moiety of the polymer. This work demonstrates that the polymer:fullerene arrangement and resulting intermolecular interactions may be key factors in determining the performance of OPV material systems

Increased open-circuit voltage of organic solar cells by reduced donor-acceptor interface area.

The charge carrier lifetime in small molecule: C60 photovoltaic devices is increased by reducing the physical interface area availabe for recombination. For donor contents below 10%, the gain in open-circuit voltage (Voc) depends logarithmically on the interface area while the energy of the interfacial charge-transfer state ECT remains invariant. © 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

Increased open-circuit voltage of organic solar cells by reduced donor-acceptor interface area

The charge carrier lifetime in small molecule: C60 photovoltaic devices is increased by reducing the physical interface area availabe for recombination. For donor contents below 10%, the gain in open-circuit voltage (Voc) depends logarithmically on the interface area while the energy of the interfacial charge-transfer state ECT remains invariant. © 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

Last Generation Solar Cells in Outer Space: A STEM Outreach Project with Middle and High School Students in Colombia

As part of an unprecedented collaborative outreach effort, we implemented an innovative STEM outreach project, where more than 80 middle and high school students from different traditionally underrepresented school districts in Colombia-with no previous knowledge on material science or photovoltaics-created Last Generation Solar Cells (LGSCs) that were part of several suborbital spaceflight missions. As a result, the students were able to contrast visual and instrumental data obtained from the solar cells and modules that were launched to space with similar samples that remained on earth to measure the degradation that occurs during spaceflight conditions. At the same time, the students that participated were able to cultivate their curiosity, strengthen their scientific skills and increase their interest in pursuing careers in STEM fields. These experiences were possible thanks to an extraordinary collaborative network between public and private entities and the use of project-based education as a powerful driver of development, especially for low-to-middle-income countries, such as Colombia. Here, we share our methodology for constructing photovoltaic devices in rural settings, and we show the progression and impact of this novel scientific outreach project

Umweltentwicklungsplan der Stadt Neuss. Anwendungsbezogene Analyse von Methoden zur Datenerhebung, -bewertung und -verknuepfung. Bd. 1 Textteil. Abschlussbericht

Within the framework of this research project comprising 32 sub-projects, a valid database meeting municipal requirements was set up to evaluate the quality of the environment in urban ecosystems. This database is to serve as a model for other municipalities. A precaution-oriented, regionalized environmental-quality target system in the form of synoptic maps was derived from this database. This system, which has been developped for planning purposes, displays - considering the tasks of air-, water- and soil-protection, nature- and countryside conservation - the degree of pollution and whether areas of the city qualify for protection. The key element of the environmental development plan is a digital environmental atlas based on the ALK-GIAP and Arc-View geoinformation systems, which displays the results of the studies for all areas of the city on 182 thematic maps. Each map is documented on a clearly-structured information sheet. A test of success of the system revealed that the regionalized environmental targets could easily be incorporated in the planning and that the importance attached to environmental protection by the municipal authorities was increased as a result. Case examples show how conflicts between environmental protection and other issues were successfully resolved or minimized. Furthermore, the report gives other municipalities suggestions how to set up their own environmental information systems and how to evaluate and link the results. (orig.)Im Rahmen des 32 Teilprojekte umfassenden Forschungsvorhabens wurde exemplarisch fuer andere Kommunen eine methodisch abgesicherte, kommunalen Anforderungen entsprechende Datenbasis zur Bewertung der Umweltqualitaet in urbanen Oekosystemen aufgebaut und daraus ein vorsorgeorientiertes, planungsrelevantes, regionalisiertes Umweltqualitaetszielsystem in Form von synoptischen Karten abgeleitet, das medienuebergreifend den Belastungsgrad und die Schutzwuerdigkeit von Flaechen im Stadtgebiet darstellt. Kernstueck des Umweltentwicklungsplanes ist ein digitaler Umweltatlas auf der Basis der Geoinformationssysteme ALK-GIAP und Arc-View, der die Untersuchungsergebnisse auf 182 thematischen Karten flaechendeckend und repraesentativ darstellt und vom Umweltamt mit grossem Erfolg zur Bearbeitung aller raumbezogenen umweltrelevanten Fragestellungen eingesetzt wird. Der Inhalt sowie die zugrundeliegenden Mess-, Erhebungs- und Auswertungsmethoden jeder Karte werden auf einem uebersichtlich gegliederten Informationsbogen fuer die Oeffentlichkeit dokumentiert. Eine Erfolgskontrolle ergab, dass sich die regionalisierten Umweltziele gut in die Planung umsetzen liessen und die Stellung des Umweltschutzes in der Verwaltung staerkten. Anhand von Fallbeispielen wird gezeigt, wie Zielkonflikte zwischen Umweltschutz und anderen Belangen in Neuss erfolgreich ausgeraeumt bzw. minimiert werden konnten. Der Bericht gibt ferner anderen Kommunen Anregungen zum Aufbau eigener Umweltinformationssysteme sowie zur Bewertung und Verknuepfung der Ergebnisse. (orig.)SIGLEAvailable from TIB Hannover: F98B1110+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Reducing burn-in voltage loss in polymer solar cells by increasing the polymer crystallinity

In order to commercialize polymer solar cells, the fast initial performance losses present in many high efficiency materials will have to be managed. This burn-in degradation is caused by light-induced traps and its characteristics depend on which polymer is used. We show that the light-induced traps are in the bulk of the active layer and we find a direct correlation between their presence and the open-circuit voltage loss in devices made with amorphous polymers. Solar cells made with crystalline polymers do not show characteristic open circuit voltage losses, even though light-induced traps are also present in these devices. This indicates that crystalline materials are more resistant against the influence of traps on device performance. Recent work on crystalline materials has shown there is an energetic driving force for charge carriers to leave amorphous, mixed regions of bulk heterojunctions, and charges are dominantly transported in pure, ordered phases. This energetic landscape allows efficient charge generation as well as extraction and also may benefit the stability against light-induced traps

Umweltentwicklungsplan der Stadt Neuss. Anwendungsbezogene Analyse von Methoden zur Datenerhebung, -bewertung und -verknuepfung. Bd. 2 Kartenteil. Abschlussbericht

Within the framework of this research project comprising 32 sub-projects, a valid database meeting municipal requirements was set up to evaluate the quality of the environment in urban ecosystems. This database is to serve as a model for other municipalities. A precaution-oriented, regionalized environmental-quality target system in the form of synoptic maps was derived from this database. This system, which has been developped for planning purposes, displays - considering the tasks of air-, water- and soil-protection, nature- and countryside conservation - the degree of pollution and whether areas of the city qualify for protection. The key element of the environmental development plan is a digital environmental atlas based on the ALK-GIAP and Arc-View geoinformation systems, which displays the results of the studies for all areas of the city on 182 thematic maps. Each map is documented on a clearly-structured information sheet. A test of success of the system revealed that the regionalized environmental targets could easily be incorporated in the planning and that the importance attached to environmental protection by the municipal authorities was increased as a result. Case examples show how conflicts between environmental protection and other issues were successfully resolved or minimized. Furthermore, the report gives other municipalities suggestions how to set up their own environmental information systems and how to evaluate and link the results. This second part contains the maps belonging to the research project. (orig.)Im Rahmen des 32 Teilprojekte umfassenden Forschungsvorhabens wurde exemplarisch fuer andere Kommunen eine methodisch abgesicherte, kommunalen Anforderungen entsprechende Datenbasis zur Bewertung der Umweltqualitaet in urbanen Oekosystemen aufgebaut und daraus ein vorsorgeorientiertes, planungsrelevantes, regionalisiertes Umweltqualitaetszielsystem in Form von synoptischen Karten abgeleitet, das medienuebergreifend den Belastungsgrad und die Schutzwuerdigkeit von Flaechen im Stadtgebiet darstellt. Kernstueck des Umweltentwicklungsplanes ist ein digitaler Umweltatlas auf der Basis der Geoinformationssysteme ALK-GIAP und Arc-View, der die Untersuchungsergebnisse auf 182 thematischen Karten flaechendeckend und repraesentativ darstellt und vom Umweltamt mit grossem Erfolg zur Bearbeitung aller raumbezogenen umweltrelevanten Fragestellungen eingesetzt wird. Der Inhalt sowie die zugrundeliegenden Mess-, Erhebungs- und Auswertungsmethoden jeder Karte werden auf einem uebersichtlich gegliederten Informationsbogen fuer die Oeffentlichkeit dokumentiert. Eine Erfolgskontrolle ergab, dass sich die regionalisierten Umweltziele gut in die Planung umsetzen liessen und die Stellung des Umweltschutzes in der Verwaltung staerkten. Anhand von Fallbeispielen wird gezeigt, wie Zielkonflikte zwischen Umweltschutz und anderen Belangen in Neuss erfolgreich ausgeraeumt bzw. minimiert werden konnten. Der Bericht gibt ferner anderen Kommunen Anregungen zum Aufbau eigener Umweltinformationssysteme sowie zur Bewertung und Verknuepfung der Ergebnisse. Dieser 2. Teil enthaelt die Karten. (orig.)SIGLEAvailable from TIB Hannover: F98D1111+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

JMJD8 Regulates Angiogenic Sprouting and Cellular Metabolism by Interacting With Pyruvate Kinase M2 in Endothelial Cells

Objective-Jumonji C (JmjC) domain-containing proteins modify histone and nonhistone proteins thereby controlling cellular functions. However, the role of JmjC proteins in angiogenesis is largely unknown. Here, we characterize the expression of JmjC domain-containing proteins after inducing endothelial differentiation of murine embryonic stem cells and study the function of JmjC domain-only proteins in endothelial cell (EC) functions. Approach and Results-We identified a large number of JmjC domain-containing proteins regulated by endothelial differentiation of murine embryonic stem cells. Among the family of JmjC domain-only proteins, Jmjd8 was significantly upregulated on endothelial differentiation. Knockdown of Jmjd8 in ECs significantly decreased in vitro network formation and sprouting in the spheroid assay. JMJD8 is exclusively detectable in the cytoplasm, excluding a function as a histone-modifying enzyme. Mass spectrometry analysis revealed JMJD8-interacting proteins with known functions in cellular metabolism like pyruvate kinase M2. Accordingly, knockdown of pyruvate kinase M2 in human umbilical vein ECs decreased endothelial sprouting in the spheroid assay. Knockdown of JMJD8 caused a reduction of EC metabolism as measured by Seahorse Bioscience extracellular flux analysis. Conversely, overexpression of JMJD8 enhanced cellular oxygen consumption rate of ECs, reflecting an increased mitochondrial respiration. Conclusions-Jmjd8 is upregulated during endothelial differentiation and regulates endothelial sprouting and metabolism by interacting with pyruvate kinase M2

Author Correction: Embedding physics domain knowledge into a Bayesian network enables layer-by-layer process innovation for photovoltaics (npj Computational Materials, (2020), 6, 1, (9), 10.1038/s41524-020-0277-x)

10.1038/s41524-020-00349-9npj Computational Materials6