Applying direct heteroarylation synthesis to evaluate organic dyes as the core component in PDI-based molecular materials for fullerene-free organic solar cells

Direct heteroarylation has emerged as a versatile and powerful tool to access π-conjugated materials through atom-economical Pd-catalyzed carbon–carbon bond forming reactions. Employing this synthetic protocol has enabled the facile evaluation of a series of organic dyes in a PDI-dye-PDI framework. Material properties are largely dictated by the PDI components, but the incorporation of either thienoisoindigo, diketopyrrolopyrrole or isoindigo has been shown to influence the ionization potential and absorption profiles of the final materials. Solution-processable organic solar cell devices were fabricated to investigate the influence of the different dye cores on photovoltaic performance when paired with the donor polymer PTB7-Th. It was found that the diketopyrrolopyrrole-based material out-performed the other organic dyes, demonstrating energy losses of less than 0.6 eV, promising efficiencies when cast from non-halogenated solvents and the ability to dictate self-assembly induced by small volume fractions of the high-boiling solvent additive 1,8-diiodooctane to reach best device efficiencies of 4.1%

Effect of side chains on the electronic and photovoltaic properties of diketopyrrolopyrrole-based molecular acceptors

Four molecular electron acceptors based on a common phthalimide end-capped diketopyrrolopyrrole pconjugated backbone, solubilized by different alkyl groups, have been synthesized. The influence of the nature and position of the solubilizing alkyl chains attached at the three constitutive blocks has been investigated. Results collected from UV-Vis absorption spectroscopy, cyclic voltammetry, solar cells fabrication and testing as well as atomic force microscopy show that the mode of substitution has negligible effect at the molecular level but strongly affects the material self-assembling properties, charge carrier transport and in turn, devices performances

A Model of Vertical Oligopolistic Competition

This paper develops a model of successive oligopolies with endogenous market entry, allowing for varying degrees of product differentiation and entry costs in both markets. Our analysis shows that the downstream conditions dominate the overall profitability of the two-tier structure while the upstream conditions mainly affect the distribution of profits. We compare the welfare effects of upstream versus downstream deregulation policies and show that the impact of deregulation may be overvalued when ignoring feedback effects from the other market. Furthermore, we analyze how different forms of vertical restraints influence the endogenous market structure and show when they are welfare enhancing

Simply Complex: The Efficient Synthesis of an Intricate Molecular Acceptor for High-Performance Air-Processed and Air-Tested Fullerene-Free Organic Solar Cells

A perylene diimide (PDI) flanked diketopyrrolopyrrole (DPP) π-conjugated small molecule has been synthesized through an efficient and sustainable direct heteroarylation protocol. When paired with the donor polymer PTB7-Th, air-processed and tested bulk-heterojunction (BHJ) organic solar cells (OSCs) achieved a high power conversion efficiency (PCE) of 5.6%. The new acceptor showed favorable morphological changes upon solvent vapor annealing leading to a near 3-fold increase in PCE. This result is among the best reported utilizing DPP-based acceptors in air-processed and tested OSCs. All solar cells exhibited good air and light stability over a 35-day evaluation period

The Optimization of Direct Heteroarylation and Sonogashira Cross-Coupling Reactions as Efficient and Sustainable Synthetic Methods To Access π-Conjugated Materials with Near-Infrared Absorption

Two π-conjugated thienoisoindigo-based organic small molecules have been designed to be synthetically accessible through sustainable direct heteroarylation or Sonogashira C–C bond forming cross-coupling reactions utilizing a heterogeneous palladium catalyst. To access these materials, one molecule, TII-ThNaph2, contains a thiophene π-bridge to facilitate direct heteroarylation protocols, whereas the other, TII-AcNaph2, contains an acetylene π-bridge required for Sonogashira couplings. The synthetic route to both final materials was optimized to investigate the reactivity of thienoisoindigo, which to this point has not been significantly explored in comparison to other popular organic dyes such as diketopyrrolopyrrole and isoindigo. Considering the reported interest of thienoisoindigo-based materials in organic solar cells and field-effect transistors, both final materials have been characterized for their optical, electrochemical and thermal properties offering a comparison of the structure–property relationships that manifest as a result of the two different π-bridging units

Thienoisoindigo end-capped molecular donors for organic photovoltaics: Effect of the central π-conjugated connector

The synthesis, characterization and preliminary evaluation of two thienoisoindigo (TII) based molecules as donor materials in air processed bulk heterojunction solar cells are reported herein. The latter were built by grafting TII dyes on two different π-conjugated central cores, namely the cyclopentadithiophene and the fluorene units. Once blended with fullerene derivatives, power conversion efficiencies approaching 3% were measured, ranking amongst the highest reported value for thienoisoindigo-based molecular materials

‘We need to get together and make ourselves heard’: everyday online spaces as incubators of political action

This article examines to what extent, and how, people engaging in political talk within ‘non-political’ discussion forums – online lifestyle communities – leads to political (or personal) action or calls-to-action. The analysis is framed in the context of wider questions of citizenship, civic engagement and political mobilization. To capture everyday political talk amongst citizens requires us to move beyond the now widely analysed online spaces of formal politics. Instead, we focus on online third spaces concerning lifestyle issues such as parenting, personal finance and popular culture. Drawing on a content analysis of three popular UK-based discussion forums over the course of five years (2010–2014), we found that (for two of the three cases) such spaces were more than just talking shops. Rather they were spaces where political actions not only emerged, but where they seemed to be cultivated. Discussions embedded in the personal lives of participants often developed – through talk – into political actions aimed at government (or other) authorities. The article sheds light on the contributing factors and processes that (potentially) trigger and foster action emerging from political talk and provides insight into the mobilization potential of third spaces

Does Gambling-Focused Treatment Affect Mental Health and Quality of Life? A Systematic Review and Meta-Analysis

Abstract: Cognitive-behavioral (CB) techniques have received substantial empirical support for reducing gambling disorder symptoms and behavior. What has not been established is whether gambling-focused treatment reduces psychological problems and improves quality of life. Individuals experiencing gambling-related harms report that sustained recovery involves changing both gambling behaviors and psychological problems and building a meaningful life. The current systematic review and meta-analysis aimed to examine the effect of CB techniques targeting gambling harms on nontargeted outcomes such as psychological problems and quality of life. Following PRISMA guidelines, a systematic article search was conducted to locate published studies of randomized controlled trials of CB techniques targeting gambling harms and reporting nontargeted outcomes. Random effects meta-analysis was used to quantify the effect of CB techniques on nontargeted outcomes. Ten studies representing 797 participants were included. Eight studies reported the effect of CB techniques on anxiety, 8 on depression, 3 on substance use, and 7 on quality of life. CB techniques significantly reduced anxiety (g = -0.44), depression (g = -0.35), gambling frequency (g = -0.30), and gambling intensity (g = -0.36) at posttreatment, but not substance use. CB techniques also significantly improved quality of life (g = 0.39) at posttreatment. Implications: The targeted reduction of gambling harms may serve as a mechanism of change for reducing psychological problems and improving quality of life. Future studies should employ longitudinal designs to understand the associations between gambling reductions and changes in nontargeted recovery outcomes over time