K-band ESR studies of structural anisotropy in P3HT and P3HT/PCBM blend polymer solid films: Paramagnetic defects after continuous wave Xe-lamp photolysis

K-band electron spin resonance (ESR) technique was employed to study films of regioregular poly(3-hexylthiophene) (P3HT) and P3HT/PCBM ([6,6]-phenyl- C61-butyric acid methyl ester) blends to estimate their structural macroscopic anisotropy. As for nematic liquids (or liquid crystals) our consideration was based on the approach that the free energy of self-organised polymer molecules of P3HT is a function of molecular orientation and therefore chains in polymer films exhibit some degree of orientational order. The lamellar molecular orientation of the films was confirmed by angular-dependent ESR spectroscopy of polarons, which were considered as a localised paramagnetic centre with an unpaired carbon π-electron of the thiophene ring. The additional ESR signal initiated by the UV/visible CW Xe-lamp illumination of the films at air atmosphere was attributed to the negative polaron (trapped photo-electron) on the polymer chain, as well as to the radical due to chain degradation. © 2009 Elsevier Ltd. All rights reserved

The development of renewable energies and supply security: A trade-off analysis

This paper analyzes the effects of the green transformation on the German electricity sector with respect to the energy political triangle. It focuses on how the development of renewable energies will affect security of electricity supply. In a cost-benefit analysis, the value of supply security is compared with its costs of provision. More specifically, the benefits of maintaining the present quality of electricity supply are the avoided social damages from electricity outages and are compared with the respective investment costs in the low- and medium-voltage distribution grid. It is shown that the transformation process towards a green and decentralized production structure will be costly for society, even though the costs can be reduced by different measures

K-band ESR studies of structural anisotropy in P3HT and P3HT/PCBM blend polymer solid films: Paramagnetic defects after continuous wave Xe-lamp photolysis

K-band electron spin resonance (ESR) technique was employed to study films of regioregular poly(3-hexylthiophene) (P3HT) and P3HT/PCBM ([6,6]-phenyl- C61-butyric acid methyl ester) blends to estimate their structural macroscopic anisotropy. As for nematic liquids (or liquid crystals) our consideration was based on the approach that the free energy of self-organised polymer molecules of P3HT is a function of molecular orientation and therefore chains in polymer films exhibit some degree of orientational order. The lamellar molecular orientation of the films was confirmed by angular-dependent ESR spectroscopy of polarons, which were considered as a localised paramagnetic centre with an unpaired carbon π-electron of the thiophene ring. The additional ESR signal initiated by the UV/visible CW Xe-lamp illumination of the films at air atmosphere was attributed to the negative polaron (trapped photo-electron) on the polymer chain, as well as to the radical due to chain degradation. © 2009 Elsevier Ltd. All rights reserved

TRESR study of the photo-induced electron transfer in P3DDT/maleic anhydride blend in THF solution under UV flash photolysis

Photo-induced electron transfer (PET) between a poly(3-dodecylthiophene) (P3DDT) and maleic anhydride (MA) in their blend in liquid solution of tetrahydrofuran was observed by the time-resolved electron spin resonance (TRESR) under UV flash photolysis at 308 nm. The observed spectra were identified as free-radical signals of positive polarons on polymer chains and MA anion radicals. Their emissive chemical induced dynamic electron polarization (CIDEP) originated mainly from excited triplet states (triplet mechanism of CIDEP). Analysis of radical spectra integral intensity distribution shows at the influence of radical pair mechanism (RPM) of CIDEP with the positive sign of the exchange interaction constant (J > 0). The last is attributed to Coulombic interaction between geminately formed polarons and MA anion radicals. The spin relaxation times of radicals were determined by fitting the time evolution of the TRESR signal at near-resonance positions of the field using the Bloch equations and direct Fourier transform analysis. © 2008 Elsevier B.V. All rights reserved

Improvement of P3HT-ICBA solar cell photovoltaic characteristics due to the incorporation of the maleic anhydride additive: P3HT morphology study of P3HT-ICBA and P3HT-ICBA-MA films by means of X-band LESR

© 2014 Published by Elsevier B.V. A light-induced electron spin resonance (LESR) X-band study of poly(3-hexylthiophene)/indene-C60 bisadduct P3HT/ICBA flexible solid films containing the additive maleic anhydride (MA) is presented. An increase of P3HT crystalline domain orientation in P3HT:ICBA:MA in comparison with P3HT:ICBA films was confirmed by the angular LESR spectra dependence of P3HT positive polarons. It was assumed that the average increase of power conversion efficiency in P3HT:ICBA:MA solar cells films, relative to P3HT:ICBA, is connected with the more effective crystalline P3HT phase orientation due to the MA sublimation from the composites blends during annealing. The relative average increase of power conversion efficiency of SC films containing MA in comparison to pure P3HT:ICBA blends is estimated to be a factor of (1.15) higher, while the concentrations of functional composites (polymer/fullerene) in blends made with MA decrease by up to 25-30%

Assessing the Strength and Effectiveness of Renewable Electricity Feed-In Tariffs in European Union Countries

In the last two decades, feed-in tariffs (FIT) and renewable portfolio standards (RPS) have emerged as two of the most popular policies for supporting renewable electricity (RES-E) generation in the developed world. A few studies have assessed their effectiveness, but most do not account for policy design features and market characteristics that influence policy strength. In this paper, we employ 1992-2008 panel data to conduct the first analysis of the effectiveness of FIT policies in promoting solar photovoltaic (PV) and onshore wind power development in 26 European Union countries. We develop a new indicator for FIT strength that captures variability in tariff size, contract duration, digression rate, electricity price, and electricity generation cost to estimate the resulting return on investment. We then regress this indicator on added RES-E capacity using a fixed effects specification. We find that FIT policies have driven solar PV and onshore wind capacity development in the EU. However, this effect is overstated without controls for country characteristics and may be concealed without accounting for the unique design of each policy. We provide empirical evidence that the interaction of policy design and market dynamics are more important determinants of RES-E development than policy enactment alone