The effect of side-chain substitution and hot processing on diketopyrrolopyrrole-based polymers for organic solar cells

The effects of cold and hot processing on the performance of polymer-fullerene solar cells are investigated for diketopyrrolopyrrole (DPP) based polymers that were specifically designed and synthesized to exhibit a strong temperature-dependent aggregation in solution. The polymers, consisting of alternating DPP and oligothiophene units, are substituted with linear and second position branched alkyl side chains. For the polymer-fullerene blends that can be processed at room temperature, hot processing does not enhance the power conversion efficiencies compared to cold processing because the increased solubility at elevated temperatures results in the formation of wider polymer fibres that reduce charge generation. Instead, hot processing seems to be advantageous when cold processing is not possible due to a limited solubility at room temperature. The resulting morphologies are consistent with a nucleation-growth mechanism for polymer fibres during drying of the films

A Universal Route to Fabricate n-i-p Multi-Junction Polymer Solar Cells via Solution Processing

The interconnection layer (ICL) that connects adjacent subcells electrically and optically in solution-processed multi-junction polymer solar cells must meet functional requirements in terms of work functions, conductivity, and transparency, but also be compatible with the multiple layer stack in terms of processing and deposition conditions. Using a combination of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, diluted in near azeotropic water/n-propanol dispersions as hole transport layer, and ZnO nanoparticles, dispersed in isoamyl alcohol as electron transport layer, a novel, versatile ICL has been developed for solution-processed tandem and triple-junction solar cells in an n-i-p architecture. The ICL has been incorporated in six different tandem cells and three different triple-junction solar cells, employing a range of different polymer-fullerene photoactive layers. The new ICL provided an essentially lossless contact in each case, without the need of adjusting the formulations or deposition conditions. The approach permitted realizing complex devices in good yields, providing a power conversion efficiency up to 10%

Prevalência de angina pectoris em Pelotas, RS

FUNDAMENTO: A cardiopatia isquêmica é a doença responsável pelo maior número de mortes no mundo, sendo a angina sua principal manifestação. OBJETIVO: Determinar a prevalência de angina e de possível angina e sua distribuição conforme as principais características sócio-demográficas entre adultos com idade igual ou maior que 40 anos. MÉTODOS: Estudo transversal de base populacional com moradores da área urbana da cidade de Pelotas (RS) entre os meses de outubro e dezembro de 2007. Foi adotado o plano de amostragem por conglomerados em dois estágios - setores censitários e domicílios. As prevalências de angina e de possível angina foram definidas de acordo com o questionário de Rose. Essas condições foram avaliadas conforme as características sócio-demográficas: idade, sexo, cor da pele, condição econômica e escolaridade. Para a coleta dos dados, foram aplicados questionários padronizados por meio de entrevista com os indivíduos em seus domicílios. A taxa de não respondentes foi de 6,8%. RESULTADOS: A prevalência de angina entre os 1.680 indivíduos participantes do estudo foi de 8,2 % (IC 95%: 6,7 - 9,6), enquanto a de possível angina, 12,3% (IC 95%: 10,6 - 14,0). As prevalências de angina e de possível angina foram maiores entre os indivíduos do sexo feminino, de cor da pele preta/parda, de pior condição econômica e de menor escolaridade. A prevalência de angina foi maior entre indivíduos mais velhos. Não se observou diferença para possível angina. CONCLUSÃO: A prevalência de angina e de possível angina mostrou-se alta, acometendo cerca de 20% da população de Pelotas

Solution-processed tin oxide-PEDOT:PSS interconnecting layers for efficient inverted and conventional tandem polymer solar cells

Tin oxide nanoparticles are employed as an electron transporting layer in solution‐processed polymer solar cells. Tin oxide based devices yield excellent performance and can interchangeably be used in conventional and inverted device configurations. In combination with poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as a hole transporting layer, tin oxide forms an effective interconnecting layer (ICL) for tandem solar cells. Conventional and inverted tandem cells with this ICL provide efficiencies up to 10.4% in good agreement with optical‐electrical modeling simulations. The critical advantage of tin oxide in an ICL in a conventional tandem structure over the commonly used zinc oxide is that the latter requires the use of a pH‐neutral formulation of PEDOT:PSS to fabricate the ICL, limiting the open‐circuit voltage (VOC) because of its low work function. The SnO2/PEDOT:PSS ICL, on the other hand, provides a nearly loss‐free VOC

The Impact of Device Polarity on the Performance of Polymer-Fullerene Solar Cells

Diketopyrrolopyrrole (DPP)-conjugated polymers are a versatile class of semiconductors for application in organic solar cells because of their tunable optoelectronic properties. A record power conversion efficiency (PCE) of 9.4% was recently achieved for DPP polymers, but further improvements are required to reach true efficiency limits. Using five DPP polymers with different chemical structures and molecular weights, the device performance of polymer:fullerene solar cells is systematically optimized by considering device polarity, morphology, and light absorption. The polymer solubility is found to have a significant effect on the optimal device polarity. Soluble polymers show a 10-25% increase in PCE in inverted device configurations, while the device performance is independent of device polarity for less soluble DPP derivatives. The difference seems related to the polymer to fullerene weight ratio at the ZnO interface in inverted devices, which is higher for more soluble DPP polymers. Optimization of the nature of the cosolvent to narrow the fibril width of polymers in the blends toward the exciton diffusion length enhances charge generation. Additionally, the use of a retroreflective foil increases absorption of light. Combined, the effects afford a PCE of 9.6%, among the highest for DPP-based polymer solar cells. c.2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Consensus molecular subgroups (CMS) of colorectal cancer (CRC) and first-line efficacy of FOLFIRI plus cetuximab or bevacizumab in the FIRE3 (AIO KRK-0306) trial.

BACKGROUND: FIRE-3 compared first-line therapy with FOLFIRI plus either cetuximab or bevacizumab in 592 KRAS exon 2 wild-type metastatic colorectal cancer (mCRC) patients. The consensus molecular subgroups (CMS) are grouping CRC samples according to their gene-signature in four different subtypes. Relevance of CMS for the treatment of mCRC has yet to be defined. PATIENTS AND METHODS: In this exploratory analysis, patients were grouped according to the previously published tumor CRC-CMSs. Objective response rates (ORR) were compared using chi-square test. Overall survival (OS) and progression-free survival (PFS) times were compared using Kaplan-Meier estimation, log-rank tests. Hazard ratios (HR) were estimated according to the Cox proportional hazard method. RESULTS: CMS classification could be determined in 438 out of 514 specimens available from the intent-to-treat (ITT) population (n = 592). Frequencies for the remaining 438 samples were as follows: CMS1 (14%), CMS2 (37%), CMS3 (15%), CMS4 (34%). For the 315 RAS wild-type tumors, frequencies were as follows: CMS1 (12%), CMS2 (41%), CMS3 (11%), CMS4 (34%). CMS distribution in right- versus (vs) left-sided primary tumors was as follows: CMS1 (27% versus 11%), CMS2 (28% versus 45%), CMS3 (10% versus 12%), CMS4 (35% versus 32%). Independent of the treatment, CMS was a strong prognostic factor for ORR (P = 0.051), PFS (P < 0.001), and OS (P < 0.001). Within the RAS wild-type population, OS observed in CMS4 significantly favored FOLFIRI cetuximab over FOLFIRI bevacizumab. In CMS3, OS showed a trend in favor of the cetuximab arm, while OS was comparable in CMS1 and CMS2, independent of targeted therapy. CONCLUSIONS: CMS classification is prognostic for mCRC. Prolonged OS induced by FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab in the FIRE-3 study appears to be driven by CMS3 and CMS4. CMS classification provides deeper insights into the biology to CRC, but at present time has no direct impact on clinical decision-making.The FIRE-3 (AIO KRK-0306) study had been registered at ClinicalTrials.gov: NCT00433927.status: publishe