Transport and Spectroscopic Studies of the Effects of Fullerene Structure on the Efficiency and Lifetime of Polythiophene-based Solar Cells

Time-dependent measurements of both power conversion efficiency and ultraviolet-visible absorption spectroscopy have been observed for solar cell blends containing the polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) with two different functionalized C60 electron acceptor molecules: commercially available [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61 butyric acid octadecyl ester (PCBOD) produced in this laboratory. Efficiency was found to decay with an exponential time dependence, while spectroscopic features show saturating exponential behavior. Time constants extracted from both types of measurements showed reasonable agreement for samples produced from the same blend. In comparison to the PCBM samples, the stability of the PCBOD blends was significantly enhanced, while both absorption and power conversion efficiency were decreased.Comment: manuscript submitted to Solar Energy Materials and Solar Cell

Influence of the isomeric composition of the acceptor on the performance of organic bulk heterojunction P3HT:bis-PCBM solar cells

We synthesized three isomeric subpopulations of bisadduct analogues of [6,6]-phenyl-C61-butyric acid methyl ester (bis-PCBM) via tether-directed control. Bulk heterojunction solar cells prepared using these isomers together with poly(3-hexylthiophene) (P3HT) resulted in an increase of Jsc from 72.4 to 79.6 A m-2, and an improvement in fill factor from 0.55 to 0.62, both with a Voc of 0.72 V resulting in an overall enhancement of the power conversion efficiency (PCE) from 2.9% to 3.5%, compared to conventional bis-PCBM.

Konfirmatori faktor analisis kepuasan kerja dosen

The University is one of the places to improve the quality of human resources. The development of education at the University of Batam city in particular has involved many parties, namely professors, the University, the community and other educational organizations. Job satisfaction in University lecturer becomes important to note. The lack of research on job satisfaction in University environment and the existing research is usually done in the industrial sector alone, so this study needs to be done at University. The object in this study to confirm the item indicators of job satisfaction lecturer. Data were collected using a questionnaire involves a number of 392 lecturers in Batam City University namely Putera Batam University, Batam University, and University of Riau Islands. Data were analyzed using SEM study of Amos. Results of the study found that, item 7 item confirming the satisfaction indicators indicators that can measure satisfaction with the Good of Fit is acceptable. The acquired results of the study can be used as a reference for the purposes of institutions, academics, and practitioners in making standards and evauasi job satisfaction. In addition, on behalf of the University needs to consider item indicators of satisfaction and need to also pay attention to other factors beyond the performed studies such as demographic factors, management and others

End-group functionalization of poly(2-oxazoline)s using methyl bromoacetate as initiator followed by direct amidation

Poly(2-alkyl/aryl-2-oxazoline)s (PAOx) are an alluring class of polymers for many applications due to the broad chemical diversity that is accessible for these polymers by simply changing the initiator, terminating agent and the monomer(s) used in their synthesis. Additional functionalities (that are not compatible with the cationic ring-opening polymerization) can be introduced to the polymers via orthogonal post-polymerization modifications. In this work, we expand this chemical diversity and demonstrate an easy and straightforward way to introduce a wide variety of functional end-groups to the PAOx, by making use of methyl bromoacetate (MeBrAc) as a functional initiator. A kinetic study for the polymerization of 2-ethyl-2-oxazoline (EtOx) in acetonitrile (CH3CN) at 140 degrees C revealed relatively slow initiation and slower polymerization than the commonly used initiator, methyl tosylate (MeOTs). Nonetheless, well-defined polymers could be obtained with MeBrAc as initiator, yielding polymers with near-quantitative methyl ester end-group functionality. Next, the post-polymerization modification of the methyl ester end-group with different amines was explored by introducing a range of functionalities, i.e. hydroxyl, amino, allyl and propargyl end-groups. The lower critical solution temperature (LCST) behavior of the resulting poly(2-ethyl-2-oxazoline)s was found to vary substantially in function of the end-group introduced, whereby the hydroxyl group resulted in a large reduction of the cloud point transition temperature of poly(2-ethyl-2-oxazoline), ascribed to hydrogen bonding with the polymer amide groups. In conclusion, this paper describes an easy and fast modular approach for the preparation of end-group functionalized PAOx

Developing the reaction kinetics for a biodiesel reactor

The aim of this paper was to investigate the kinetics of the biodiesel reaction in order to find out how best to reach 96.5% methyl ester. The purity of the biodiesel product was examined using gas chromatography to the EN14214 FAME standard and real-time optical microscopy was used to observe the reaction. The problem was the reaction doesn’t reach completion and the mechanism is not understood. It was observed that droplet size had a major influence on reaction end point and that the reaction was mass-transfer limited. This observation was confirmed by developing a mass-transfer based reaction model using the data from the batch reactor which agreed with results from other researchers. The model predicted better conversion with more mixing intensity. The results show that significant improvements could be made to the conventional FAME process

On-line monitoring of the transesterification reaction between triglycerides and ethanol using near infrared spectroscopy combined with gas chromatography

Many analytical procedures have been developed to determine the composition of reaction mixtures during transesterification of vegetable oils with alcohols. However, despite their accuracy, these methods are time consuming and cannot be easily used for on-line monitoring. In this work, a fast analytical method was developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol using Near InfraRed spectroscopy and a multivariate approach. The reactions were monitored through sequential scans of the reaction medium with a probe in a one-liter batch reactor without collecting and preparing samples. To calibrate the NIR analytical method, gas chromatography-flame ionization detection was used as a reference method. The method was validated by studying the kinetics of the EtONa-catalyzed transesterification reaction. Activation energy (51.0 kJ/mol) was also determined by considering a pseudo second order kinetics model

The effect of alcohol on the performance of lipase-immobilized enzymatic membrane reactor for esterification of (R,S)-ketoprofen

The effect of alcohols on the performance of lipase-immobilized enzymatic membrane reactor (EMR) for enantioselective esterification of (R,S)-ketoprofen has been studied. In this work, mixed solvent medium was used and the (R)-ketoprofen was reacted with the different alcohols in the presence of immobilized lipase B from Candida antartica, leaving the target product (S)-ketoprofen in its unreacted form. The alcohols involved in the reactions were ethanol, butanol, heptanol and 2-ethoxyethanol. The chain length of alcohol was found to significantly affect the performance of the esterification in EMR. Through the alcohols screening, the esterification reaction using ethanol in EMR showed higher initial rate, conversion, enzyme enantioselectivity, enantiomeric excess of substrate (ees) and enantiomeric excess of product (eep). However the results with butanol showed less inhibition effect on a wider range of temperatur

Pivalolactone, 1 interchange reactions with polypivalolactone

Ester interchange, alcoholysis, and acidolysis of polypivalolactone (PPVL) were studied by melting PPVL with bisphenol diacetates, 1, 4-butanediol, or aromatic diacids. Interchange of PPVL with the diacetates and the diol occured readily, in particular in the presence of a titanium catalyst. Melting PPVL with 10 mol-% of bisphenol-Adiacetate in the presence of 0,5 wt.% tetrabutylorthotitanate resulted in an incorporation of 33% of the diacetate in the polymer chains, whereas the logarithmic viscosity number decreased by 81%. The ester interchange was suggested to proceed by an initial cleavage of ester bonds in the polymer chain of PPVL, resulting in the formation of shorter chains, followed by a reaction between the newly formed ester end-groups and initially present hydroxyl chain ends. The acidolysis of PPVL with the diacids proved to be less effective; in the case of the acidolysis of PPVL with 10 mol-% isophthalic acid, less than 1% of the diacid was incorporated in the polymer chains and a decrease in the logarithmic viscosity number of only 22% was found. Both the high stability of the ester bond in PPVL towards acids in general and the heterogeneity of these systems were supposed to cause the behaviour of PPVL with respect to acidolysis. The results concerning the interchange reactions with PPVL were compared with studies on other polyesters

Chemistry and Biology of Streptogramin A Antibiotics

The streptogramin A antibiotics have proven to be highly active against Gram positive bacteria, particularly methicillin-resistant Staphylococcus aureus. Members of this group of compounds are characterized by a 23-membered macrocycles containing polyene, oxazole, amide and ester functionality. The chemistry and biology of these valuable antimicrobial agents is covered