Transition Metal Coordination Compounds as Novel Materials for Dye-Sensitized Solar Cells

DFT study of UV-vis-properties of thiophene-containing Cu(β-diketonato)2 - Application for DSSC

Experimental and theoretically calculated UV-vis properties of three Cu(β-diketonato)₂ complexes are presented. The Cu(β-diketonato)₂ contains β-diketones without (β-diketone = acetylacetone, (CH₃)COCH₂CO(CH₃), complex (1)), with one (β-diketone = thenoyltrifluoroacetone, (CF₃)COCH₂CO(C₄H₃S), complex (2)) and with two thiophene (β-diketone = (CF₃)COCH₂CO(C₄H₂S) (C₄H₃S), complex (3)) groups. More thiophenes on the β-diketonato ligand of Cu(β-diketonato)₂, lead to a red shift of the experimental absorbance maxima of the UV-vis of the complex, from 295 nm for complex (1), to 340 nm for complex (2) to 390 nm for complex (3). Theoretical time dependant density functional theory calculations indicate that both the two strongest absorbance peaks of the ultraviolet-visible spectrum of Cu(acetylacetonato)₂ are mainly ligand-to-metal charge-transfer excitations. However, the absorbance maxima of the UV-vis of thiophene-containing Cu(β-diketonato)₂ are mainly ligand-to-ligand charge-transfer excitations. Calculated properties such as light harvesting energy (LHE = 0.47, 0.94 and 0.99 for (1)-(3) respectively), driving force for electron injection (ΔG_inject = 1.43, 0.76 and 0.63 for (1)-(3) respectively), and driving force of dye regeneration (ΔG_regenerate = 1.85, 2.16 and 1.49 for (1)-(3) respectively), are favourable for (1)-(3) to be considered as dyes in DSSCs. However, some structural modifications are needed to prevent intramolecular charge recombination after excitation.

Investigating the Remanufacturing Potential of Dye-Sensitized Solar Cells

Resources are becoming more expensive and less accessible, for instance construction wood or semiconductors. In addition, climate change requires the conversion of the energy system to 100% renewable energy. Therefore, we need resources to prevent the climate crisis from worsening, but at the same time, we are suffering from a worsening resource crisis. State-of-the-art technologies, such as silicon-based photovoltaic or wind power plants, are harnessing renewable energy but causing problems and resource losses at the end of their useful life. This alarming situation must be addressed with renewable energy technologies that can be used longer, repaired and remanufactured, and properly recycled at the end of their useful life. An emerging technology that can complement the established systems is dye-sensitized solar cells (DSSCs). Their production is less energy intensive and they can be manufactured without toxic materials. In line with the concept of the circular economy, the service life of all products must be improved in order to reduce resource consumption. Therefore, we investigated the potential for remanufacturing DSSCs by taking apart old DSSCs, cleaning the components, and building new DSSCs from the remanufactured components. The remanufactured DSSCs have the same or higher efficiencies and can be remanufactured multiple times.