Morphology controls the thermoelectric power factor of a doped semiconducting polymer.

The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with F n TCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (σ) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (μ). The Seebeck coefficient (α) is largely independent of OCL. This reveals that, unlike σ, leveraging strategies to improve μ have a smaller impact on α. Our best-performing sample with the largest OCL, vapor-doped PBTTT:F4TCNQ thin film, has a σ of 670 S/cm and an α of 42 μV/K, which translates to a large PF of 120 μW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 μW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics

Morphology controls the thermoelectric power factor of a doped semiconducting polymer

The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with FnTCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (s) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (m). The Seebeck coefficient (a) is largely independent of OCL. This reveals that, unlike s, leveraging strategies to improve m have a smaller impact on a. Our best-performing sample with the largest OCL, vapor-doped PBTTT: F4TCNQ thin film, has a s of 670 S/cm and an a of 42 μV/K, which translates to a large PF of 120 mW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 μW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics

Many Labs 5:Testing pre-data collection peer review as an intervention to increase replicability

Replication studies in psychological science sometimes fail to reproduce prior findings. If these studies use methods that are unfaithful to the original study or ineffective in eliciting the phenomenon of interest, then a failure to replicate may be a failure of the protocol rather than a challenge to the original finding. Formal pre-data-collection peer review by experts may address shortcomings and increase replicability rates. We selected 10 replication studies from the Reproducibility Project: Psychology (RP:P; Open Science Collaboration, 2015) for which the original authors had expressed concerns about the replication designs before data collection; only one of these studies had yielded a statistically significant effect (p < .05). Commenters suggested that lack of adherence to expert review and low-powered tests were the reasons that most of these RP:P studies failed to replicate the original effects. We revised the replication protocols and received formal peer review prior to conducting new replication studies. We administered the RP:P and revised protocols in multiple laboratories (median number of laboratories per original study = 6.5, range = 3?9; median total sample = 1,279.5, range = 276?3,512) for high-powered tests of each original finding with both protocols. Overall, following the preregistered analysis plan, we found that the revised protocols produced effect sizes similar to those of the RP:P protocols (?r = .002 or .014, depending on analytic approach). The median effect size for the revised protocols (r = .05) was similar to that of the RP:P protocols (r = .04) and the original RP:P replications (r = .11), and smaller than that of the original studies (r = .37). Analysis of the cumulative evidence across the original studies and the corresponding three replication attempts provided very precise estimates of the 10 tested effects and indicated that their effect sizes (median r = .07, range = .00?.15) were 78% smaller, on average, than the original effect sizes (median r = .37, range = .19?.50)

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic.

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

Tailoring the Seebeck Coefficient of PEDOT:PSS by Controlling Ion Stoichiometry in Ionic Liquid Additives

Mixing simple additives into poly­(3,4-ethylenedioxythiophene)/poly­(styrenesulfonate) (PEDOT:PSS) dispersions can greatly enhance the thermoelectric properties of the cast films with little manufacturing cost, but design rules for many of these additives have yet to emerge. We show that controlling stoichiometry in ionic liquid (I.L.) additives can decouple morphological and electronic modifications to PEDOT:PSS and enhance its power factor by over 2 orders of magnitude. Blending I.L. additives with a 1:1 stoichiometry between cationic imidazolium (Im⁺) derivatives and anionic bis­(trifluoromethane)­sulfonamide (TFSI^–) groups into PEDOT:PSS dispersions raised the film conductivity to ∼1000 S/cm. The Seebeck coefficient, which gives insight into the electronic structure as well as thermoelectric performance, remained unchanged. This behavior mimics that of popular high-boiling solvent additives such as dimethyl sulfoxide and ethylene glycol, which restructure the film morphology to enhance carrier mobility. Blending I.L. additives with a 4:1 stoichiometry between Im⁺ and TFSI^– groups raises the conductivity in a similar manner but also enhances the Seebeck coefficient. This selective Seebeck enhancement proceeds from the interaction of excess Im⁺ with anionic poly­(styrenesulfonate) (PSS^–) groups, similar to previous studies using inorganic salts, that results in a shift in charge carrier populations. Inorganic salts by themselves cannot raise the conductivity of PEDOT:PSS to appropriate values since they lack the solvent restructuring effect. These I.L. additives combine the effects of high-boiling solvents and diffuse ions, with the ability to tailor the Seebeck coefficient through ion stoichiometry

Defective thermoregulation, impaired lipid metabolism, but preserved adrenergic induction of gene expression in brown fat of mice lacking C/EBPβ

C/EBPβ (CCAAT/enhancer-binding protein β) is a transcriptional regulator of the UCP1 (uncoupling protein-1) gene, the specific marker gene of brown adipocytes that is responsible for their thermogenic capacity. To investigate the role of C/EBPβ in brown fat, we studied the C/EBPβ-null mice. When placed in the cold, C/EBPβ(−/−) mice did not maintain body temperature. This cold-sensitive phenotype occurred, although UCP1 and PGC-1α (peroxisome-proliferator-activated receptor γ co-activator-1α) gene expression was unaltered in brown fat of C/EBPβ(−/−) mice. The UCP1 gene promoter was repressed by the truncated inhibitory C/EBPβ isoform LIP (liver-enriched transcriptional inhibitory protein, the truncated inhibitory C/EBPβ isoform). Since C/EBPβ-null mice lack both C/EBPβ isoforms, active LAP (liver-enriched transcriptional activatory protein, the active C/EBPβ isoform) and LIP, the absence of LIP may have a stronger effect than the absence of LAP upon UCP1 gene expression. Gene expression for UCP2 and UCP3 was not impaired in all tissues analysed. In primary brown adipocytes from C/EBPβ(−/−) mice, induction of gene expression by noradrenaline was preserved. In contrast, the expression of genes related to lipid storage was impaired, as was the amount of triacylglycerol mobilized after acute cold exposure in brown fat from C/EBPβ(−/−) mice. LPL (lipoprotein lipase) activity was also impaired in brown fat, but not in other tissues of C/EBPβ(−/−) mice. LPL protein levels were also diminished, but this effect was independent of changes in LPL mRNA, suggesting that C/EBPβ is involved in the post-transcriptional regulation of LPL gene expression in brown fat. In summary, defective thermoregulation owing to the lack of C/EBPβ is associated with the reduced capacity to supply fatty acids as fuels to sustain brown fat thermogenesis