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Hole-induced polymerized interfacial film of polythiophene as co-sensitizer and back-electron injection barrier layer in dye-sensitized TiO2 nanotube array
摘要： In this work, we demonstrate that an ultra-thin film of polythiophene deposited interfacially via hole-induced polymerization on the surface of dye-sensitized TiO2 nanotube array acts as co-sensitizer, and hinders back-electron transfer in a DSSC. Consequently, the dark current, and the recombination reactions can be suppressed, leading to an improved number of electron density at the TiO2 array electrode. Thus, an enhanced photocurrent, and power conversion efficiency of the device is achieved. This logical concept is experimentally justified, and the device, after polythiophene interfacial treatment, demonstrates an enhanced power conversion efficiency by the factor of 39.19%.
关键词： Interfacial treatment,Back-electron injection barrier,Hole-induced polymerization,TiO2 nanotubes,Polythiophene co-sensitizer,DSSC
更新于2025-09-04 15:30:14
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Catalytic deracemization of chiral allenes by sensitized excitation with visible light
摘要： Chiral compounds exist as enantiomers that are non-superimposable mirror images of each other. Owing to the importance of enantiomerically pure chiral compounds—for example, as active pharmaceutical ingredients—separation of racemates (1:1 mixtures of enantiomers) is extensively performed. Frequently, however, only a single enantiomeric form of a chiral compound is required, which raises the question of how a racemate can be selectively converted into a single enantiomer. Such a deracemization process is entropically disfavoured and cannot be performed by a conventional catalyst in solution. Here we show that it is possible to photochemically deracemize chiral compounds with high enantioselectivity using irradiation with visible light (wavelength of 420 nanometres) in the presence of catalytic quantities (2.5 mole per cent) of a chiral sensitizer. We converted an array of 17 chiral racemic allenes into the respective single enantiomers with 89 to 97 per cent enantiomeric excess. The sensitizer is postulated to operate by triplet energy transfer to the allene, with different energy-transfer efficiencies for the two enantiomers. It thus serves as a unidirectional catalyst that converts one enantiomer but not the other, and the decrease in entropy is compensated by light energy. Photochemical deracemization enables the direct formation of enantiopure materials from a racemic mixture of the same compound, providing a novel approach to the challenge of creating asymmetry.
关键词： chiral sensitizer,triplet energy transfer,deracemization,chiral compounds,visible light,enantiomers,photochemical
更新于2025-09-04 15:30:14