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Isomerism is common in fullerene derivatives, and the isomer‐dependent photovoltaic performance of fullerene derivatives is envisaged recently. This review article outlines recent progresses on isomerism of [6,6]‐phenyl‐C61 (or C71)‐butyric acid methyl esters (PCBMs), one of the most prevalent electronic acceptors in organic or perovskite solar cells. Recent developments about the effects of PCBMs isomers on the photovoltaic performance and device stability of organic or perovskite solar cells are summarized, including the mono‐ and bis‐adduct of PC71BM as well as the bis‐adduct of PC61BM. The open questions and future directions with involvement of isomeric PCBMs are also discussed. [ABSTRACT FROM AUTHOR]

As the most prevalently used fullerene-based electron acceptor in organic–inorganic solar cells, [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) was isolated into three typical isomers of α-, β1- and β2-PC71BM with comparable molecular orbital energy levels for exemplifying a formulation engineering based on blending the three isomers to improve photovoltaic performance. The power conversion efficiency (PCE), photocurrent hysteresis and stability of planar heterojunction perovskite (CH3NH3PbI3) solar cells have been optimized by formulation engineering with mixed PC71BM (α : β1 : β2 = 17 : 1 : 2), the specific mixture which represents the best electron acceptor superior to either each of the purified isomers or any other ternary isomers of PC71BM. Microscopic analyses support that molecular aggregation of the isomeric PC71BM was critical to influence the surface morphology and, in turn, the PCE in the range of 0.38–17.56% of the perovskite solar cells involved. This finding about isomer-dependent photovoltaic performance launches a heretofore unknown strategy of formulation engineering for making efficient electron acceptors by mixing various fullerene derivatives having isomeric structures or beyond. [ABSTRACT FROM AUTHOR]

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC71BM (phenyl-C71-butyric acid methyl ester) usually has a 'random' composition of mixed regioisomers or stereoisomers. Here PC71BM has been isolated into three typical isomers, α-, β1- and β2-PC71BM, to establish the isomer-dependent photovoltaic performance on changing the ternary composition of α-, β1- and β2-PC71BM. Mixing the isomers in a ratio of α/β1/β2=8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC71BM as photoactive layer (PTB7=poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b:4,5- b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophenediyl]]). The three typical PC71BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average-performing PCE of 1.28-7.44 % due to diverse self-aggregation of individual or mixed PC71BM isomers in the otherwise same polymer solar cells. [ABSTRACT FROM AUTHOR]

The aim of this paper was to assess the biosorption properties of extracellular polymeric substances (G-EPS, P-EPS and W-EPS) extracted from three different activated sludges called AS-G, AS-P and AS-W. The compositions of the EPSs were determined. Sludge grown in lab had more EPS than those from a Sewage Treatment Plant, and that sludge fed on glucose had more EPS than if fed on peptone. The biosorption capacities of the EPSs with two metals Cu and Zn were examined successively. The maximal biosorption capacity of EPS is increased in the following order: G-EPS > W-EPS > P-EPS. All EPSs showed stronger binding properties for Zn than Cu, and this adsorption process was described well by Langmuir and Freundlich models, respectively. The excellent fit between pseudo second-order equations and adsorption process indicates that the chemisorption may be the rate limiting step. FTIR analyses revealed that the main chemical groups involved in the interactions between metals were apparently alcohol, carboxyl and amino. These groups were part of the EPS structural polymers, polysaccharides, proteins and hydrocarbon-like products. [ABSTRACT FROM AUTHOR]

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC 71 BM (phenyl-C 71 -butyric acid methyl ester) usually has a "random" composition of mixed regioisomers or stereoisomers. Here PC 71 BM has been isolated into three typical isomers, α-, β 1 - and β 2 -PC 71 BM, to establish the isomer-dependent photovoltaic performance on changing the ternary composition of α-, β 1 - and β 2 -PC 71 BM. Mixing the isomers in a ratio of α/β 1 /β 2 =8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC 71 BM as photoactive layer (PTB7=poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]). The three typical PC 71 BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average-performing PCE of 1.28-7.44 % due to diverse self-aggregation of individual or mixed PC 71 BM isomers in the otherwise same polymer solar cells., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)